从头认识Spring-2.2 默认自动装配

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这一章节我们来讨论一下默认自动装配

1.domain

蛋糕类：（不变）

package com.raylee.my_new_spring.my_new_spring.ch02.topic_1_4;

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_4;

public class Chief {
	private Cake cake = null;

	private String name = "";

	public Chief(Cake cake) {
		this.cake = cake;
	}

	public String getName() {
		return name;
	}

	public Cake makeOneCake() {
		System.out.println(getName() + " make " + cake.getName());
		return 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_1;

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_4/ApplicationContext-test.xml" })
public class ChiefTest {

	@Autowired
	private ApplicationContext applicationContext;

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

3.配置文件（重点）

（1）下面是按照平常的配置方式来配置的

<?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_4.Cake"
		p:name="blueberryCheeseCake" scope="prototype" />

	<bean id="jack"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_4.Chief"
		p:name="jack" autowire="constructor" />
</beans>

根据上面的配置文件测试输出：

jack make blueberryCheeseCake

（2）下面是使用默认自动配置

<?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"
	default-autowire="constructor">

	<bean id="blueberryCheeseCake"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_5.Cake"
		p:name="blueberryCheeseCake" scope="prototype" />

	<bean id="jack"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_5.Chief"
		p:name="jack" />
</beans>

根据上面的配置文件测试输出：

jack make blueberryCheeseCake

对比上面的配置文件，我们发现有两点不同：

（1）jack里面没有了autowire标签

（2）在文件头上面多出了default-autowire标签，这个标签代表的是这个配置文件里面所有的bean，将优先以这种方式装配，例如上面的constructor

（3）default-autowire可以理解成为批量处理的形式，把配置文件里面的bean通通按照同一个方式装配

（4）当bean里面和头文件里面同时出现autowire，以bean的设置为优先，例如下面的配置文件：

<?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"
	default-autowire="byName">

	<bean id="blueberryCheeseCake"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_5.Cake"
		p:name="blueberryCheeseCake" scope="prototype" />

	<bean id="jack"
		class="com.raylee.my_new_spring.my_new_spring.ch02.topic_1_5.Chief"
		p:name="jack" autowire="constructor" />
</beans>

根据上面的配置文件测试输出：

jack make blueberryCheeseCake

总结：这一章节主要介绍了default-autowire的使用以及相应的注意点。

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

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

从头认识Spring-2.2 默认自动装配

标签：

原文地址：http://blog.csdn.net/raylee2007/article/details/50654252