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spring <context:annotation-config> 跟 <context:component-scan>诠释及区别

2016-05-30 18:04 513 查看
<context:annotation-config> 和 <context:component-scan>的区别


Difference between <context:annotation-config> vs <context:component-scan>

 

<context:annotation-config>
 是用于激活那些已经在spring容器里注册过的bean(无论是通过xml的方式还是通过package
sanning的方式)上面的注解,是一个注解处理工具。

<context:component-scan>除了具有
<context:annotation-config>的功能之外,
<context:component-scan>
还可以在指定的package下扫描以及注册javabean 。

 

下面我们通过例子来详细查看他们的区别,

有三个class   A,B,C,并且B,C的对象被注入到A中.

 

[java] view
plain copy

 





package com.xxx;  

public class B {  

  public B() {  

    System.out.println("creating bean B: " + this);  

  }  

}  

  

package com.xxx;  

1eedf

public class C {  

  public C() {  

    System.out.println("creating bean C: " + this);  

  }  

}  

  

package com.yyy;  

import com.xxx.B;  

import com.xxx.C;  

public class A {   

  private B bbb;  

  private C ccc;  

  public A() {  

    System.out.println("creating bean A: " + this);  

  }  

  public void setBbb(B bbb) {  

    System.out.println("setting A.bbb with " + bbb);  

    this.bbb = bbb;  

  }  

  public void setCcc(C ccc) {  

    System.out.println("setting A.ccc with " + ccc);  

    this.ccc = ccc;   

  }  

}  

 

 

在applicationContext.xml中加入下面的配置 :

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bbb"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"ccc"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
</</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">></span></code>


 

加载applicationContext.xml配置文件,将得到下面的结果:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@c2ff5
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@1e8a1f6
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1e152c5
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@c2ff5
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@1e8a1f6</span></code>


 

OK, 这个结果没什么好说的,就是完全通过xml的方式,不过太过时了,下面通过注解的方式来简化我们的xml配置文件

首先,我们使用autowire的方式将对象bbb和ccc注入到A中:

 

 

[java] view
plain copy

 





package com.yyy;  

import org.springframework.beans.factory.annotation.Autowired;  

import com.xxx.B;  

import com.xxx.C;  

public class A {   

  private B bbb;  

  private C ccc;  

  public A() {  

    System.out.println("creating bean A: " + this);  

  }  

  @Autowired  

  public void setBbb(B bbb) {  

    System.out.println("setting A.bbb with " + bbb);  

    this.bbb = bbb;  

  }  

  @Autowired  

  public void setCcc(C ccc) {  

    System.out.println("setting A.ccc with " + ccc);  

    this.ccc = ccc;  

  }  

}  

 
 

 

然后,我们就可以从applicationContext.xml中移除下面的配置

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bbb"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">property name</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"ccc"</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> ref</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>


 

移除之后,我们的applicationContext.xml配置文件就简化为下面的样子了

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>


 

当我们加载applicationContext.xml配置文件之后,将得到下面的结果:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@5e5a50
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@54a328
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@a3d4cf</span></code>


 

OK, 结果是错误的的,究竟是因为什么呢?为什么我们的属性没有被注入进去呢?

是因为注解本身并不能够做任何事情,它们只是最基本的组成部分,我们需要能够处理这些注解的处理工具来处理这些注解

这就是<context:annotation-config>
 所做的事情

我们将applicationContext.xml配置文件作如下修改:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<span style="color: rgb(255, 0, 0);"><</span></span><span style="color: rgb(255, 0, 0);"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"bBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.B"</span></span><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"cBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx.C"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">
<span style="color: rgb(255, 0, 0);"><</span></span><span style="color: rgb(255, 0, 0);"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span></code>


 

当我们加载applicationContext.xml配置文件之后,将得到下面的结果:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@15663a2
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@cd5f8b
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@15663a2
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@cd5f8b</span></code>


 

OK, 结果正确了。

下面演示<context:annotation-config> 跟 <context:component-scan>区别:

但是如果我们将代码作如下修改:

 

 

[java] view
plain copy

 





package com.xxx;  

import org.springframework.stereotype.Component;  

@Component  

public class B {  

  public B() {  

    System.out.println("creating bean B: " + this);  

  }  

}  

  

package com.xxx;  

import org.springframework.stereotype.Component;  

@Component  

public class C {  

  public C() {  

    System.out.println("creating bean C: " + this);  

  }  

}  

  

package com.yyy;  

import org.springframework.beans.factory.annotation.Autowired;  

import org.springframework.stereotype.Component;  

import com.xxx.B;  

import com.xxx.C;  

@Component  

public class A {   

  private B bbb;  

  private C ccc;  

  public A() {  

    System.out.println("creating bean A: " + this);  

  }  

  @Autowired  

  public void setBbb(B bbb) {  

    System.out.println("setting A.bbb with " + bbb);  

    this.bbb = bbb;  

  }  

  @Autowired  

  public void setCcc(C ccc) {  

    System.out.println("setting A.ccc with " + ccc);  

    this.ccc = ccc;  

  }  

}  

 
 

 

 

applicationContext.xml配置文件修改为:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>


 

当我们加载applicationContext.xml配置文件之后,却没有任何输出,这是为什么呢?

那是因为<context:annotation-config />仅能够在已经在已经注册过的bean上面起作用。

对于没有在spring容器中注册的bean,它并不能执行任何操作。
但是不用担心,
<context:component-scan>除了具有
<context:annotation-config
/>的功能之外,还具有自动将带有@component,@service,@Repository等注解的对象注册到spring容器中的功能。

我们将applicationContext.xml配置文件作如下修改:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>


 

当我们加载applicationContext.xml的时候,会得到下面的结果:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@1be0f0a
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@80d1ff</span></code>


 

这是什么原因呢?

是因为我们仅仅扫描了com.xxx包及其子包的类,而class  A是在com.yyy包下,所以就扫描不到了

下面我们在applicationContext.xml中把com.yyy也加入进来:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><span style="color: rgb(255, 0, 0);">/>

</span></span></code><span style="color: rgb(255, 0, 0);"><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">"com.xxx,com.yyy"</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">/></span></span>
然后加载applicationContext.xml就会得到下面的结果:<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"></code>
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@cd5f8b
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@15ac3c9
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@ec4a87
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@cd5f8b
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@15ac3c9</span></code>


 

哇,结果正确啦 !

回头看下我们的applicationContext.xml文件,已经简化为:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>

</span></code><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="font-family: 'Courier New', Courier, monospace; color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="font-family: 'Courier New', Courier, monospace; color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">"com.xxx,com.yyy"</span><span class="pun" style="font-family: 'Courier New', Courier, monospace; border: 0px; padding: 0px; margin: 0px; font-size: 1em; vertical-align: baseline; background-color: transparent;">/></span>


 

了。

 

那如果我们在applicationContext.xml手动加上下面的配置,也就是说既在applicationContext.xml中手动的注册了A的实例对象,同时,通过component-scan去扫描并注册B,C的对象

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span></span><span style="color: rgb(255, 0, 0);"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/>
</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></span></code>


 

结果仍是正确的:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1d64c37
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span>
16451
<span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>


 

虽然class  A并不是通过扫描的方式注册到容器中的 ,但是
<context:component-scan>
 所产生的的处理那些注解的处理器工具,会处理所有绑定到容器上面的bean,不管是通过xml手动注册的还是通过scanning扫描注册的。

那么,如果我们通过下面的方式呢?我们既配置了<context:annotation-config />,又配置了<context:component-scan base-package="com.xxx" />,它们都具有处理在容器中注册的bean里面的注解的功能。会不会出现重复注入的情况呢?

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">annotation</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">config </span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">context</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">component</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">scan base</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">-</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">package</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.xxx"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"><</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bean id</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"aBean"</span><span class="kwd" style="color: rgb(0, 0, 139); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">class</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">=</span><span class="str" style="color: rgb(128, 0, 0); border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">"com.yyy.A"</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">/></span></code>


 

不用担心,不会出现的:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@1d64c37
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>


 

因为
<context:annotation-config
/>和
 
<context:component-scan>同时存在的时候,前者会被忽略。也就是那些@autowire,@resource等注入注解只会被注入一次


哪怕是你手动的注册了多个处理器,spring仍然只会处理一次:

 

[xml] view
plain copy

 





<context:annotation-config />  

<context:component-scan base-package="com.xxx" />  

<bean id="aBean" class="com.yyy.A" />  

<bean id="bla" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  

<bean id="bla1" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  

<bean id="bla2" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  

<bean id="bla3" class="org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor" />  

 

 

结果仍是正确的:

 
<code style="border: 0px; padding: 0px; margin: 0px; font-family: Consolas, Menlo, Monaco, 'Lucida Console', 'Liberation Mono', 'DejaVu Sans Mono', 'Bitstream Vera Sans Mono', 'Courier New', monospace, serif; vertical-align: baseline;"><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">creating bean B</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
creating bean C</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87
creating bean A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">:</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;"> com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">yyy</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">A@25d2b2
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">bbb with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">B@157aa53
setting A</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">ccc with com</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">xxx</span><span class="pun" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">.</span><span class="pln" style="border: 0px; padding: 0px; margin: 0px; vertical-align: baseline; background-color: transparent;">C@ec4a87</span></code>
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