Spring属性装配之属性类型是另外一个被装载的类

如果属性类型是另外一个被装载的类，可以使用标签来装配属性值。

比如一个JavaBean中的某个属性是另外一个JavaBean的对象，而且要装备这个属性，那么就需要使用来标签ref进行装配。

MyBean类的hello属性是HelloService的类型，代码如下：

MyBean.java

package chapter22;

public class MyBean {
	private int iValue;
	private String strName;
	private HelloService hello;

	public int getiValue() {
		return iValue;
	}

	public void setiValue(int iValue) {
		this.iValue = iValue;
	}

	public String getStrName() {
		System.out.println("getStrName()方法被调用");
		return strName;
	}

	public void setStrName(String strName) {
		this.strName = strName;
		System.out.println("setStrName()方法被调用");
	}

	public HelloService getHello() {
		System.out.println("getHello()方法被调用");
		return hello;
	}

	public void setHello(HelloService hello) {
		this.hello = hello;
		System.out.println("setHello()方法被调用");
	}
}
 

然后在applicationContext.xml中进行配置，配置如下：

<?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-2.5.xsd">
	<bean id="helloservice" class="chapter22.HelloServiceImpl">
		<property name="greeting" value="greeting Xu Wei">
		</property>
	</bean>
	<bean id="myBean" class="chapter22.MyBean">
		<property name="hello">
			<ref bean="helloservice" />
		</property>
		<property name="strName" value="Xu Wei"></property>
	</bean>
</beans> 

添加一个TestMyBean类，代码如下

TestMyBean.java

package chapter22;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class TestMyBean {
	public static void main(String args[]) {
		ApplicationContext ctx = new FileSystemXmlApplicationContext(
				"src//applicationContext.xml");
		MyBean mb = (MyBean) ctx.getBean("myBean");
		// System.out.println(mb.getHello());
		System.out.println(mb.getHello().getGreeting());
		System.out.println(mb.getStrName());
	}
}
 

最后的输出结果如下：

log4j:WARN No appenders could be found for logger (org.springframework.context.support.FileSystemXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
setGreeting()方法被调用
setHello()方法被调用
setStrName()方法被调用
getHello()方法被调用
getGreeting()方法被调用
greeting Xu Wei
getStrName()方法被调用
Xu Wei

分析：

mb.getStrName是直接传参进去的，而这里通过ref穿进去的是hello，hello本身是一个对象，所以mb.getHello().getGreeting()获得的是hello配置的参数。