Spring高级注入之属性值注入

实际应用中，某个实例的属性可能是另一个对象的一个属性，Spring支持将bean实例的属性值直接赋值给一个变量

属性值的注入，是通过PropertyPathFactoryBean完成的，PropertyPathFactoryBean用来获取目标bean的属性，获得的值可以注入到其他bean,也可以定义成新的bean

实体类：

package Bean.superIOCparam;

public class Person {
   private Son son;
   private String age;
public String getAge() {
    return age;
}
public void setAge(String age) {
    this.age = age;
}
public Son getSon() {
    return son;
}
public void setSon(Son son) {
    this.son = son;
}
}


package Bean.superIOCparam;

public class Son {
  private String age;

public String getAge() {
    return age;
}

public void setAge(String age) {
    this.age = age;
}
}

 配置文件：提供四种注入

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>

  <bean id="person" class="Bean.superIOCparam.Person" singleton="false">
     <property name="age">
        <value>30</value>
     </property>
     <property name="son">
        <bean class="Bean.superIOCparam.Son">
           <property name="age">
              <value>16</value>
           </property>
        </bean>
     </property>
  </bean>
  
  <!--如下将会将person的属性son的属性age传入son1实例的age属性-->
    <bean id="son1" class="Bean.superIOCparam.Son">
        <property name="age">
          <!--以下是访问bean属性的简单方式,这样可以将person这个bean的age属性赋值给son1这个bean的age属性-->           
         <bean id="person.son.age" class="org.springframework.beans.factory.config.PropertyPathFactoryBean"/>
        </property>
    </bean>
    
    <!-- 以下将会获得结果son,它将是person bean的son的数值-->
    <bean id="son2" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
       <property name="targetBeanName">
         <value>person</value>
       </property>
       <property name="propertyPath">
         <value>son</value>
       </property>
    </bean>
    
     <!-- 以下将会获得结果16,它将是person bean的son的age属性-->
    <bean id="son3" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
       <property name="targetBeanName">
         <value>person</value>
       </property>
       <property name="propertyPath">
         <value>son.age</value>
       </property>
    </bean>
    
    <!-- 以下会获得结果为30 ,它将是获得该bean的内部bean的age属性-->
    <bean id="son4" class="org.springframework.beans.factory.config.PropertyPathFactoryBean">
        <property name="targetObject">
            <bean class="Bean.superIOCparam.Person">
                <property name="age"><value>30</value></property>
            </bean>
        </property>
        <property name="propertyPath"><value>age</value></property>
    </bean>
</beans>

 测试代码：

public static void main(String[] args) throws Exception {
        
        String path=new Test().getClass().getResource("/").getPath();
        String realpath=path.substring(1, path.length());
        ApplicationContext context=new FileSystemXmlApplicationContext(realpath+"/superIOCparam.xml");
        Son son1=(Son)context.getBean("son1");
        Son son2=(Son)context.getBean("son2");

        System.out.println("person age is:"+son1.getAge());
        System.out.println("person age is:"+son2.getAge());
        System.out.println(context.getBean("son3"));
        System.out.println(context.getBean("son4"));
    }

 

运行结果：

person age is:16
person age is:16
16
30