从头认识Spring-2.1 自动装配（2）-byType（2）

为了解决配置文件里面出现多个同类型的Bean而byType无法匹配的问题，引入了primary和autowire-candidate属性。

1.primary

由于所有bean默认的primary都是true，因此笔者认为这个属性没有太大的用处

2.autowire-candidate

这个属性的意思是，是否排除自己，如果排除了自己， 那么当使用byType的时候，这个Bean就不列入候选bean里面，看下面的例子：

（1）domain

蛋糕类：（不变）

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3;

public class Cake {

	private String name = "";

	public String getName() {
		return name;
	}

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

}

厨师类：（不变）

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3;

public class Chief {
	private Cake cake = null;

	private String name = "";

	public Cake getCake() {
		return cake;
	}

	public String getName() {
		return name;
	}

	public Cake makeOneCake() {
		System.out.println(getName() + " make " + getCake().getName());
		return cake;
	}

	public void setCake(Cake cake) {
		this.cake = cake;
	}

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

}

（2）测试类：（不变）

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {
		"/com/raylee/my_new_spring/my_new_spring/ch02/topic_1_3/ApplicationContext-test.xml" })
public class ChiefTest {

	@Autowired
	private ApplicationContext applicationContext;

	@Test
	public void testChief() {
		Chief jack = (Chief) applicationContext.getBean("jack");
		jack.makeOneCake();
		Chief rose = (Chief) applicationContext.getBean("rose");
		rose.makeOneCake();
	}
}

（3）配置文件：（重点）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context" xmlns:p="http://www.springframework.org/schema/p"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx"
	xmlns:aop="http://www.springframework.org/schema/aop" xmlns:util="http://www.springframework.org/schema/util"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
		http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd
		http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.0.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

	<bean id="blueberryCheeseCake"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3.Cake"
		p:name="blueberryCheeseCake" scope="prototype" />

	<bean id="cake"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3.Cake"
		p:name="cake" scope="prototype" autowire-candidate="false" />

	<bean id="jack"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3.Chief"
		p:name="jack">
		<property name="cake" ref="cake" />
	</bean>

	<bean id="rose"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_3.Chief"
		autowire="byType" p:name="rose" />
</beans>

上面的配置文件使用autowire-candidate排除了cake这个bean，因此会出现下面的输出。

测试输出：

jack make cake
rose make blueberryCheeseCake

总结：这一章节主要介绍解决配置文件里面出现多个同类型的Bean而byType无法匹配的问题。

目录：http://blog.csdn.net/raylee2007/article/details/50611627

我的github：https://github.com/raylee2015/my_new_spring