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

转自:https://blog.csdn.net/vvhesj/article/details/47661001

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:

 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>

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：

 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       
 7     @Configuration  
 8     public class SpringConfig {  
 9       
10         @Bean  
11         public Piano piano(){  
12             return new Piano();  
13         }  
14         @Bean(name = "counter")   
15         public Counter counter(){  
16             return  new Counter(12,"Shake it Off",piano());  
17         }  
18     }

三、基础类代码

Counter：

 1     package SpringStudy.Model;  
 2       
 3     public class Counter {  
 4         public  Counter() {  
 5         }  
 6       
 7         public  Counter(double multiplier, String song,Instrument instrument) {  
 8             this.multiplier = multiplier;  
 9             this.song = song;  
10             this.instrument=instrument;  
11         }  
12       
13         private double multiplier;  
14       
15         private String song;  
16       
17         @Resource  
18         private Instrument instrument;  
19       
20         public double getMultiplier() {  
21             return multiplier;  
22         }  
23       
24         public void setMultiplier(double multiplier) {  
25             this.multiplier = multiplier;  
26         }  
27       
28       
29         public String getSong() {  
30             return song;  
31         }  
32       
33         public void setSong(String song) {  
34             this.song = song;  
35         }  
36       
37         public Instrument getInstrument() {  
38             return instrument;  
39         }  
40       
41         public void setInstrument(Instrument instrument) {  
42             this.instrument = instrument;  
43         }  
44       
45     }

Piano类

 1     package SpringStudy.Model;  
 2       
 3       
 4     public class Piano {  
 5         private String name="Piano";  
 6         private String sound;  
 7       
 8         public String getName() {  
 9             return name;  
10         }  
11       
12         public void setName(String name) {  
13             this.name = name;  
14         }  
15       
16         public String getSound() {  
17             return sound;  
18         }  
19       
20         public void setSound(String sound) {  
21             this.sound = sound;  
22         }  
23       
24     }

四、调用测试类

 1     package webMyBatis;  
 2       
 3     import org.springframework.context.ApplicationContext;  
 4     import org.springframework.context.annotation.AnnotationConfigApplicationContext;  
 5     import SpringStudy.Model.Counter;  
 6       
 7     public class SpringTest {  
 8         public static void main(String[] args) {  
 9             //ApplicationContext ctx = new ClassPathXmlApplicationContext("spring/bean.xml");// 读取bean.xml中的内容  
10             ApplicationContext annotationContext = new AnnotationConfigApplicationContext("SpringStudy");  
11             Counter c = annotationContext.getBean("counter", Counter.class);// 创建bean的引用对象  
12             System.out.println(c.getMultiplier());  
13             System.out.println(c.isEquals());  
14             System.out.println(c.getSong());  
15                 System.out.println(c.getInstrument().getName());  
16         }  
17     }

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