自动化装配Bean

Posted 2021-12-01 gede

一、创建 CompactDisc接口和SgetPeppers实现类

　　CompactDisc接口方法为播放。SgtPeppers实现CompactDisc接口。

1 package soundsystem;
2 
3 public interface CompactDisc {
4   void play();
5 
6 }

 1 package soundsystem;
 2 
 3 import org.springframework.stereotype.Component;
 4 //component为spring中bean扫描标识
 5 @Component
 6 public class SgtPeppers implements CompactDisc {
 7 
 8   private String title = "歌德";  
 9   private String artist = "gede";
10   
11   public void play() {
12     System.out.println("Playing " + title + " by " + artist);
13   }
14 
15 }

二、启用spring组件扫描

　　1、通过java配置启用

　　　　添加 @Configuration @ComponentScan 两个注解即可。

　　　　【注】使用ComponentScan时，若配置文件和bean在同一个包，省略基础包备注也可以。

1 package soundsystem;
2 import org.springframework.context.annotation.ComponentScan;
3 import org.springframework.context.annotation.Configuration;
4 
5 @Configuration
6 @ComponentScan（"soundsystem"）
7 public class JavaConfig {
8 
9 }

 

　　2、通过xml配置启用：<context:component-scan base-package="soundsystem"></context:component-scan>  如果没有自动提示或者报错，在namespace中添加context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: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-4.1.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">

    <context:component-scan base-package="soundsystem"></context:component-scan>

</beans>

三、编写测试类，并运行

　　1、创建test包，分别通过java配置和xnl配置实现测试

　　　　java配置为：AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(soundsystem.JavaConfig.class);

　　　　xml配置为：ClassPathXmlApplicationContext context =new ClassPathXmlApplicationContext("applicationContext.xml");

 1 package test;
 2 
 3 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 4 import org.springframework.context.support.ClassPathXmlApplicationContext;
 5 import soundsystem.CompactDisc;
 6 import soundsystem.SgtPeppers;
 7 
 8 public class Test {
 9     public static void main(String[] args) {
10     //基于java类中配置上下文
11     //AnnotationConfigApplicationContext context = 
12             new AnnotationConfigApplicationContext(soundsystem.JavaConfig.class); 
13     //基于xml配置上下文
14     ClassPathXmlApplicationContext context =
15             new ClassPathXmlApplicationContext("applicationContext.xml");
16     
17     CompactDisc cd=context.getBean(SgtPeppers.class);
18     cd.play();
19     }
20 }