Spring框架学习（3）：spring属性配置的细节

本篇文章主要讲一下Spring属性配置的细节

一、Bean之间的引用

首先我们知道，组成应用程序的Bean经常需要相互协助以完成应用程序的功能，要使Bean能够相互访问就必须在Bean配置文件中指定对Bean的引用。有两种方法使Bean之间构成引用的关系

1.在配置文件中通过ref属性为Bean的属性或构造器参数指定对Bean的引用

首先写两个类Person和Address

package beans;

public class Person {
private String name;

private Address address;

public String getName() {
return name;
}

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

public Address getAddress() {
return address;
}

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

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

}

package beans;

public class Address {
private String city;
private String street;
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getStreet() {
return street;
}
public void setStreet(String street) {
this.street = street;
}
@Override
public String toString() {
return "Address [city=" + city + ", street=" + street + "]";
}

}

然后在配置文件中配置他们的引用关系

 

写一个main函数测试一下

 

2.在属性或者构造器中包含Bean的声明，即内部Bean，外部的其他Bean无法访问到该内部Bean。

在配置文件中配置他们的引用关系，其他不改变

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<bean id="person" class="beans.Person">
<property name="name" value="Tom"></property>
<property name="address">
<bean class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Shangxiajiu"></property>
</bean>
</property>
</bean>

</beans>

二、Bean属性中带有特殊字符

当property属性的value值带有特殊字符，例如<>时，可以使用以下方法配置

<bean id="person" class="beans.Person">
<property name="name" value="Tom"></property>
<property name="address">
<bean class="beans.Address">
<property name="city">
<value><![CDATA[<GuangZhou>]]></value>
</property>
<property name="street" value="Shangxiajiu"></property>
</bean>
</property>
</bean>

三、为级联属性赋值

<bean id="person" class="beans.Person">
<property name="name" value="Tom"></property>
<property name="address" ref="address"></property>
<property name="address.city" value="ShangHai"></property>
</bean>

需要注意的是，属性需要先初始化才可以为级联属性赋值

四、为集合属性赋值

配置List属性：

修改一下Person类，将地址改为List

package beans;

import java.util.List;

public class Person {
private String name;

private List<Address> addresses;

public String getName() {
return name;
}

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

public List<Address> getAddresses() {
return addresses;
}

public void setAddresses(List<Address> addresses) {
this.addresses = addresses;
}

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

}

在配置文件中：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<bean id="address1" class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Shangxiajiu"></property>
</bean>

<bean id="address2" class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Gongyuanqian"></property>
</bean>

<bean id="person" class="beans.Person">
<property name="name" value="Tom"></property>
<property name="addresses">
<list>
<ref bean="address1"/>
<ref bean="address2"/>
</list>
</property>
</bean>

</beans>

配置Array属性与List差不多

配置Map属性：

修改一下Person类

package beans;

import java.util.List;
import java.util.Map;

public class Person {
private String name;

private Map<String, Address> addresses;

public String getName() {
return name;
}

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

public Map<String, Address> getAddresses() {
return addresses;
}

public void setAddresses(Map<String, Address> addresses) {
this.addresses = addresses;
}

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

}

修改配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<bean id="address1" class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Shangxiajiu"></property>
</bean>

<bean id="address2" class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Gongyuanqian"></property>
</bean>

<bean id="person" class="beans.Person">
<property name="name" value="Tom"></pro
4000
perty>
<property name="addresses">
<map>
<entry key="AA" value-ref="address1"></entry>
<entry key="BB" value-ref="address2"></entry>
</map>
</property>
</bean>

</beans>

五、通过p命名空间为bean属性赋值

需要先导入p命名空间，在配置文件的页面点NameSpaces，然后勾选p命名空间即可，p命名空间可以帮助我们更快捷得配置bean

配置文件如下：

<?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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<bean id="address" class="beans.Address">
<property name="city" value="GuangZhou"></property>
<property name="street" value="Shangxiajiu"></property>
</bean>

<bean id="person" class="beans.Person"
p:name="Tom" p:address-ref="address"></bean>

</beans>