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

Spring中為了減少xml中配置，可以聲明一個配置類（例如SpringConfig）來對bean進行配置。

一、首先，需要xml中進行少量的配置來啟動Java配置:

[java]

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1. <?xml version="1.0" encoding="UTF-8"?>  
2. <beans xmlns="http://www.springframework.org/schema/beans"  
3.     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"  
4.     xmlns:tx="http://www.springframework.org/schema/tx" xmlns:p="http://www.springframework.org/schema/p"  
5.     xmlns:context="http://www.springframework.org/schema/context"  
6.     xsi:schemaLocation="  
7.             http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd  
8.             http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd  
9.             http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd  
10.             http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">  
11.    <context:component-scan base-package="SpringStudy.Model">  
12.     </context:component-scan>  
13. </beans>  

<?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、定義一個配置類

用@Configuration注解該類，等價 與XML中配置beans；用@Bean标注方法等價于XML中配置bean。

代碼如下：

1. package SpringStudy;  
2. import org.springframework.context.annotation.Bean;  
3. import org.springframework.context.annotation.Configuration;  
4. import SpringStudy.Model.Counter;  
5. import SpringStudy.Model.Piano;  
6. @Configuration  
7. public class SpringConfig {  
8.     @Bean  
9.     public Piano piano(){  
10.         return new Piano();  
11.     }  
12.     @Bean(name = "counter")   
13.     public Counter counter(){  
14.         return  new Counter(12,"Shake it Off",piano());  
16. }  

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、基礎類代碼

Counter：

1. package SpringStudy.Model;  
2. public class Counter {  
3.     public  Counter() {  
5.     public  Counter(double multiplier, String song,Instrument instrument) {  
6.         this.multiplier = multiplier;  
7.         this.song = song;  
8.         this.instrument=instrument;  
10.     private double multiplier;  
11.     private String song;  
12.     @Resource  
13.     private Instrument instrument;  
14.     public double getMultiplier() {  
15.         return multiplier;  
17.     public void setMultiplier(double multiplier) {  
20.     public String getSong() {  
21.         return song;  
23.     public void setSong(String song) {  
26.     public Instrument getInstrument() {  
27.         return instrument;  
29.     public void setInstrument(Instrument instrument) {  
30.         this.instrument = instrument;  

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類

2. public class Piano {  
3.     private String name="Piano";  
4.     private String sound;  
5.     public String getName() {  
6.         return name;  
8.     public void setName(String name) {  
9.         this.name = name;  
11.     public String getSound() {  
12.         return sound;  
14.     public void setSound(String sound) {  
15.         this.sound = sound;  

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、調用測試類

1. package webMyBatis;  
2. import org.springframework.context.ApplicationContext;  
3. import org.springframework.context.annotation.AnnotationConfigApplicationContext;  
5. public class SpringTest {  
6.     public static void main(String[] args) {  
7.         //ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 讀取bean.xml中的内容  
8.         ApplicationContext annotationContext = new AnnotationConfigApplicationContext("SpringStudy");  
9.         Counter c = annotationContext.getBean("counter", Counter.class);// 建立bean的引用對象  
10.         System.out.println(c.getMultiplier());  
11.         System.out.println(c.isEquals());  
12.         System.out.println(c.getSong());  
13.             System.out.println(c.getInstrument().getName());  

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");// 讀取bean.xml中的内容

ApplicationContext annotationContext = new AnnotationConfigApplicationContext("SpringStudy");

Counter c = annotationContext.getBean("counter", Counter.class);// 建立bean的引用對象

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的話，或者使用自動掃描調用的話，代碼為