Spring受管Bean依赖注入（设值注入）

设值注入是Spring支持的多种依赖注入类型中的一种，也是最为常见的一种。设值（setter）注入指在通过调用无参构造器（或无参静态工厂方法，或工厂Bean的蜚静态工厂方法）实例化受管Bean后调用setter方法，从而建立起对象之间的依赖关系。

一、无参构造器实例化受管Bean

public class HelloWorld implements IHelloWorld {

    protected static final Log log = LogFactory.getLog(HelloWorld.class);
    private IHelloStr helloStr;

    public HelloWorld() {
        super();
    }
    public void setHelloStr(IHelloStr str) {
        this.helloStr = str;
    }
    public String getContent() {
        return helloStr.getContent();
    }
}

<?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-2.5.xsd">
    <bean name="fileHello" class="test.FileHelloStrImpl">
        <constructor-arg>
            <value>helloworld.properties</value>
        </constructor-arg>
    </bean>
    <bean id="helloWorld" class="test.HelloWorld">
        <property name="helloStr" ref="fileHello" />
    </bean>
</beans>

我们可以通过ref属性指定依赖的对象或value属性直接给出目标对象。

二、无参静态工厂方法实例化受管Bean

如果希望通过调用无参静态工厂方法获得天受管Bean，则需要往对应的POJO类中添加静态方法以，以下为实例：

public class HelloWorld implements IHelloWorld {

    protected static final Log log = LogFactory.getLog(HelloWorld.class);
    private IHelloStr helloStr;
    public void setHelloStr(IHelloStr str) {
        this.helloStr = str;
    }
    public String getContent() {
        return helloStr.getContent();
    }

    public static HelloWorld getHelloWorld(){
        return new HelloWorld();
    }
}

<?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-2.5.xsd">
     <bean id="helloWorld"  factory-method="getHelloWorld"
          class="test.HelloWorld">
          <property name="helloStr" ref="fileHello"/>
     </bean>

     <bean name="fileHello" class="test.FileHelloStrImpl">
          <constructor-arg>
               <value>helloworld.properties</value>
          </constructor-arg>
     </bean>

</beans>

三、工厂Bean的非静态工厂方法实例受管Bean

同样的如果希望通过调用工厂Bean的非静态工厂方法获得受管Bean，则需要往对应的POJO类中添加非静态方法以，实例如下：

public class HelloWorld implements IHelloWorld {

    protected static final Log log = LogFactory.getLog(HelloWorld.class);
    private IHelloStr helloStr;
    public void setHelloStr(IHelloStr str) {
        this.helloStr = str;
    }
    public String getContent() {
        return helloStr.getContent();
    }

    public HelloWorld makeHelloWorld(){
        return new HelloWorld();
    }
}

<?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-2.5.xsd">
     <bean id="helloWorldFactory" class="test.HelloWorld"/>

     <bean id="helloWorld" factory-bean="helloWorldFactory"
            factory-method="makeHelloWorld">
          <property name="helloStr" ref="fileHello"/>
     </bean>

     <bean name="fileHello"
          class="test.FileHelloStrImpl">
          <constructor-arg>
               <value>helloworld.properties</value>
          </constructor-arg>
     </bean>

</beans>

配置的helloWorldFactory受管Bean扮演了工厂Bean的角色。

转载自：http://blog.csdn.net/zhangxs_3/article/details/4345575