Spring中基于Java的配置@Configuration和@Bean用法

spring中为了减少xml中配置，可以生命一个配置类（例如SpringConfig）来对bean进行配置。

一、首先，需要xml中进行少量的配置来启动Java配置:

<?xmlversion="1.0"encoding="UTF-8"?>
<beansxmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="
http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context-3.2.xsd">
<context:component-scanbase-package="SpringStudy.Model">
</context:component-scan>
</beans>

二、定义一个配置类

用@Configuration注解该类，等价 与XML中配置beans；用@Bean标注方法等价于XML中配置bean。

代码如下：

packageSpringStudy;
importorg.springframework.context.annotation.Bean;
importorg.springframework.context.annotation.Configuration;
importSpringStudy.Model.Counter;
importSpringStudy.Model.Piano;

@Configuration
publicclassSpringConfig{

@Bean
publicPianopiano(){
returnnewPiano();
}
@Bean(name="counter")
publicCountercounter(){
returnnewCounter(12,"ShakeitOff",piano());
}
}

三、基础类代码

Counter：

packageSpringStudy.Model;

publicclassCounter{
publicCounter(){
}

publicCounter(doublemultiplier,Stringsong,Instrumentinstrument){
this.multiplier=multiplier;
this.song=song;
this.instrument=instrument;
}

privatedoublemultiplier;

privateStringsong;

@Resource
privateInstrumentinstrument;

publicdoublegetMultiplier(){
returnmultiplier;
}

publicvoidsetMultiplier(doublemultiplier){
this.multiplier=multiplier;
}


publicStringgetSong(){
returnsong;
}

publicvoidsetSong(Stringsong){
this.song=song;
}

publicInstrumentgetInstrument(){
returninstrument;
}

publicvoidsetInstrument(Instrumentinstrument){
this.instrument=instrument;
}

}

Piano类

packageSpringStudy.Model;


publicclassPiano{
privateStringname="Piano";
privateStringsound;

publicStringgetName(){
returnname;
}

publicvoidsetName(Stringname){
this.name=name;
}

publicStringgetSound(){
returnsound;
}

publicvoidsetSound(Stringsound){
this.sound=sound;
}

}

四、调用测试类

packagewebMyBatis;

importorg.springframework.context.ApplicationContext;
importorg.springframework.context.annotation.AnnotationConfigApplicationContext;
importSpringStudy.Model.Counter;

publicclassSpringTest{
publicstaticvoidmain(String[]args){
//ApplicationContextctx=newClassPathXmlApplicationContext("spring/bean.xml");//读取bean.xml中的内容
ApplicationContextannotationContext=newAnnotationConfigApplicationContext("SpringStudy");
Counterc=annotationContext.getBean("counter",Counter.class);//创建bean的引用对象
System.out.println(c.getMultiplier());
System.out.println(c.isEquals());
System.out.println(c.getSong());
System.out.println(c.getInstrument().getName());
}
}

注意：如果是在xml中配置beans和bean的话，或者使用自动扫描调用的话，代码为

ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 读取bean.xml中的内容
Counter c = ctx.getBean("counter", Counter.class);// 创建bean的引用对象

五、运行结果

12.0
false
Shake it Off
Piano