Spring Beans 自动装配 使用XML配置列子（带源码）

原文地址：http://websystique.com/spring/spring-beans-auto-wiring-example-using-xml-configuration/

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Bean 装配是为了提供需要完成任务所依赖bean。Spring中，bean可以通过手动和自动两种方式装配。

手动装配 :
通过 <property> 或者 <constructor> 标签中的ref
属性

<!-- default example (autowire="no") -->
<bean id="driver" class="com.websystique.spring.domain.Driver">
<property name="license" ref="license"/>
</bean>

<bean id="license" class="com.websystique.spring.domain.License" >
<property name="number" value="123456ABCD"/>
</bean>

自动装配：使用<bean> 标签中的autowire

<bean id="application" class="com.websystique.spring.domain.Application" autowire="byName"/>

在此例中，bean将会通过Spring自动装配特性自动的装配。

有4种方式：

autowire="byName"

:
根据属性名自动装配。如果另外一个bean属性名于此相同则自动装配。

autowire="byType"

:
根据bean的类型进行自动装配。

autowire="constructor"

:
根据构造方法装自动装配。如果其他bean的构造参数和此相同则此bean将被装配到其他bean的构造方法。

autowire="no"

:
不自动装配。和通过ref指定一样。

1. autowire=”byName” 例子

package com.websystique.spring.domain;

public class Application {

private ApplicationUser applicationUser;

public ApplicationUser getApplicationUser() {
return applicationUser;
}

public void setApplicationUser(ApplicationUser applicationUser) {
this.applicationUser = applicationUser;
}

@Override
public String toString() {
return "Application [applicationUser=" + applicationUser + "]";
}
}

package com.websystique.spring.domain;

public class ApplicationUser {

private String name;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "ApplicationUser [name=" + name + "]";
}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> 
<!-- byName example -->
<bean id="application" class="com.websystique.spring.domain.Application" autowire="byName"/>
<bean id="applicationUser" class="com.websystique.spring.domain.ApplicationUser" >
<property name="name" value="superUser"/>
</bean>

</beans>

application类的applicationUser属性 和 ApplicationUser
bean的id相同。

package com.websystique.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.websystique.spring.domain.Application;

public class AppMain {
public static void main(String args[]){
AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");

//autowire=byName
Application application = (Application)context.getBean("application");
System.out.println("Application Details : "+application);
}
}

运行结果：

Application Details : Application [applicationUser=ApplicationUser [name=superUser]]

2. autowire=”byType”例子

package com.websystique.spring.domain;

public class Employee {

private EmployeeAddress address;

public EmployeeAddress getAddress() {
return address;
}

public void setAddress(EmployeeAddress address) {
this.address = address;
}

@Override
public String toString() {
return "Employee [address=" + address + "]";
}
}

package com.websystique.spring.domain;

public class EmployeeAddress {

private String Street;
private String city;

public String getStreet() {
return Street;
}

public void setStreet(String street) {
Street = street;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

@Override
public String toString() {
return "EmployeeAddress [Street=" + Street + ", city=" + city + "]";
}
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> 
<!-- byType example -->
<bean id="employee" class="com.websystique.spring.domain.Employee" autowire="byType"/>

<bean id="employeeAddress" class="com.websystique.spring.domain.EmployeeAddress" >
<property name="street" value="112/223,SantaVila"/>
<property name="city" value="Nebraska"/>
</bean>

</beans>

Employee 类中 EmployeeAddress address 和employeeAddress 并不相同，但是是按照类型注入。所以可以装配进去。

运行：

package com.websystique.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.websystique.spring.domain.Employee;

public class AppMain {
public static void main(String args[]){
AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");

//autowire=byType
Employee employee = (Employee)context.getBean("employee");
System.out.println("Employee Details : "+employee);
}
}

输出：

3. autowire=”constructor”

package com.websystique.spring.domain;

public class Performer {

private Instrument instrument;

public Performer(Instrument instrument){
this.instrument = instrument;
}

@Override
public String toString() {
return "Performer [instrument=" + instrument + "]";
}
}

package com.websystique.spring.domain;

public class Instrument {

private String name;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

@Override
public String toString() {
return "Instrument [name=" + name + "]";
}
}

注意：Performer类有一个接收Instrument类型的参数的构造方法。

XML配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> 
<!-- constructor example -->
<bean id="performer" class="com.websystique.spring.domain.Performer" autowire="constructor"/>

<bean id="instrument" class="com.websystique.spring.domain.Instrument" >
<property name="name" value="PIANO"/>
</bean>

</beans>

Performer<span style="font-weight: bold;"><span style="font-family:Consolas, Bitstream Vera Sans Mono, Courier New, Courier, monospace;"><span style="font-size: 13px; line-height: 14.3px; white-space: pre; background-color: rgb(245, 245, 245);"><span style="color:#0000ff;"><span style="color: rgb(64, 64, 64); font-family: 'Open Sans', sans-serif; font-size: 15px; line-height: 22.5px;">类有一个接收Instrument类型的参数的构造方法。将在Spring 定义的id为instrument的装配进去，。</span></span></span></span></span>

<pre name="code" class="java">package com.websystique.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.websystique.spring.domain.Performer;

public class AppMain {
public static void main(String args[]){
AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");

//autowire=constructor
Performer performer = (Performer)context.getBean("performer");
System.out.println("Performer Details : "+performer);
}

}

运行结果：

<pre name="code" class="plain">Performer Details : Performer [instrument=Instrument [name=PIANO]]

3. autowire=”no”

<pre name="code" class="java">package com.websystique.spring.domain;

public class Driver {

private License license;

public void setLicense(License license) {
this.license = license;
}

public License getLicense() {
return license;
}

@Override
public String toString() {
return "Driver [license=" + license + "]";
}
}

package com.websystique.spring.domain;

public class License {

private String number;

public String getNumber() {
return number;
}

public void setNumber(String number) {
this.number = number;
}

@Override
public String toString() {
return "License [number=" + number + "]";
}

}

配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> 
<!-- default example (autowire="no") -->
<bean id="driver" class="com.websystique.spring.domain.Driver" autowire="no">
<property name="license" ref="license"/>
</bean>

<bean id="license" class="com.websystique.spring.domain.License" >
<property name="number" value="123456ABCD"/>
</bean>

</beans>

autowire="no" 没有什么作用。可以不写。只是不自动装载。

运行：

package com.websystique.spring;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.websystique.spring.domain.Driver;

public class AppMain {
public static void main(String args[]){
AbstractApplicationContext context = new ClassPathXmlApplicationContext("app-config.xml");

//autowire=default
Driver driver = (Driver)context.getBean("driver");
System.out.println("Driver Details : "+driver);

}
}

结果：

Driver Details : Driver [license=License [number=123456ABCD]]

下载地址：http://websystique.com/?smd_process_download=1&download_id=785