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

一、首先，需要xml中进行少量的配置来启动Java配置:

<?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: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/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">
<context:component-scan base-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：

package SpringStudy;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import SpringStudy.Model.Counter;
import SpringStudy.Model.Piano;
@Configuration
public class SpringConfig {
@Bean
public Piano piano(){
return new Piano();
}
@Bean(name = "counter")
public Counter counter(){
return new Counter(12,"Shake it Off",piano());
}
}

三、基础类代码

Counter：

package SpringStudy.Model;
public class Counter {
public Counter() {
}
public Counter(double multiplier, String song,Instrument instrument) {
this.multiplier = multiplier;
this.song = song;
this.instrument=instrument;
}
private double multiplier;
private String song;
@Resource
private Instrument instrument;
public double getMultiplier() {
return multiplier;
}
public void setMultiplier(double multiplier) {
this.multiplier = multiplier;
}
public String getSong() {
return song;
}
public void setSong(String song) {
this.song = song;
}
public Instrument getInstrument() {
return instrument;
}
public void setInstrument(Instrument instrument) {
this.instrument = instrument;
}
}

Piano类

package SpringStudy.Model;
public class Piano {
private String name="Piano";
private String sound;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSound() {
return sound;
}
public void setSound(String sound) {
this.sound = sound;
}
}

四、调用测试类

package webMyBatis;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import SpringStudy.Model.Counter;
public class SpringTest {
public static void main(String[] args) {
//ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 读取bean.xml中的内容
ApplicationContext annotationContext = new AnnotationConfigApplicationContext("SpringStudy");
Counter c = 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
--------------------- 

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