使用@Import和@ImportResource进行Spring Java config和xml的混合配置

喜欢ヅ旅行 2022-08-19 13:21 110阅读 0赞

> 最近在看《Spring in Action 4th》，讲到JavaConfig的@Import和@ImportResource的使用，于是照着例子做了个小demo，加深自己的印象。在Spring中配置有xml和JavaConfig的配置方式，相比来说，使用JavaConfig的方式配置会更利于管理，类型安全。

### demo项目结构(Maven约定)： ###

├── pom.xml
    └── src
        ├── main
        │   ├── java
        │   │   └── com
        │   │       └── jiaobuchong
        │   │           ├── config
        │   │           │   ├── CDConfig.java
        │   │           │   ├── CDPlayerConfig.java
        │   │           │   └── SoundSystemConfig.java
        │   │           ├── dao
        │   │           │   └── CompactDisc.java
        │   │           │   └── MediaPlayer.java
        │   │           └── soundsystem
        │   │               ├── BlankDisc.java
        │   │               ├── CDPlayer.java
        │   │               └── SgtPeppers.java
        │   └── resources
        │       └── cons-injec.xml
        └── test
            └── java
                └── com
                    └── jiaobuchong
                        ├── soundsystem
                            ├── CDPlayerTest.java

### dao下两个interface： ###

#### CompactDisc.java： ####

package com.jiaobuchong.dao;
    
    public interface CompactDisc {
        void play();
    }

#### MediaPlayer.java ####

package com.jiaobuchong.dao;
    
    public interface MediaPlayer {
        void play();
    }

### soundsystem包下的interface实现类： ###

#### BlankDisc.java： ####

package com.jiaobuchong.soundsystem;
    
    import com.jiaobuchong.dao.CompactDisc;
    
    import java.util.List;
    
    public class BlankDisc implements CompactDisc { 
        private String title;
        private String artist;
        private List<String> tracks;
    
        public BlankDisc(String title, String artist, List<String> tracks) {
            this.title = title;
            this.artist = artist;
            this.tracks = tracks;
        }
    
        public void play() {
            System.out.println("Playing " + title + " by " + artist);
            for (String track : tracks) {
                System.out.println("-Track: " + track);
            }
        }
    }

#### CDPlayer.java： ####

package com.jiaobuchong.soundsystem;
    
    import com.jiaobuchong.dao.MediaPlayer;
    import org.springframework.beans.factory.annotation.Autowired;
    
    public class CDPlayer implements MediaPlayer { 
        private CompactDisc cd;
    
        public CDPlayer(CompactDisc cd) {
            this.cd = cd;
        }
    
        public void play() {
            cd.play();
        }
    }

#### SgtPeppers.java： ####

package com.jiaobuchong.soundsystem;
    
    import com.jiaobuchong.dao.CompactDisc;
    import org.springframework.stereotype.Component;
    
    public class SgtPeppers implements CompactDisc { 
        private String title = "Sgt. Pepper's Lonely Hearts Club Band";
        private String artist = "The Beatles";
        public void play() {
            System.out.println("Playing " + title + " by " + artist);
        }
    }

### config包下的三个配置类 ###

#### CDConfig.java： ####

package com.jiaobuchong.config;
    
    import com.jiaobuchong.dao.CompactDisc;
    import com.jiaobuchong.soundsystem.SgtPeppers;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration  // @Configuration注解表示定义一个配置类
    public class CDConfig { 
                // 方法名heyGirl即是bean的name
        @Bean   // 将SgtPeppers注册为 SpringContext中的bean
        public CompactDisc heyGirl() {
            return new SgtPeppers();  // CompactDisc类型的
        }
    }

@Bean注解等同于xml的配置：

#### CDPlayerConfig.java： ####

package com.jiaobuchong.config;
    
    import com.jiaobuchong.dao.CompactDisc;
    import com.jiaobuchong.soundsystem.CDPlayer;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Import;
    
    @Configuration
    @Import(CDConfig.class)  //导入CDConfig的配置
    public class CDPlayerConfig {
        @Bean(name = "cDPlayer")
        public CDPlayer cdPlayer(CompactDisc heyGirl) {  
        /* 这里注入的bean是 上面CDConfig.java中的name为heyGirl的CompactDisc类型的bean*/
            return new CDPlayer(heyGirl);
        }
    
    }

这里的注解@Bean等同于xml配置的元素，

#### SoundSystemConfig.java： ####

package com.jiaobuchong.config;
    
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Import;
    import org.springframework.context.annotation.ImportResource;
    
    @Configuration
    @Import(CDPlayerConfig.class)  
    @ImportResource("classpath:cons-injec.xml") //导入xml配置项
    public class SoundSystemConfig {
    
    }

@ImportResource等同于xml配置：

### xml配置文件 ###

#### cons-injec.xml： ####

<?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:c="http://www.springframework.org/schema/c" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd ">
           <bean id="compactDisc" class="com.jiaobuchong.soundsystem.BlankDisc" c:_0="Sgt. Pepper's Lonely Hearts Club Band" c:_1="The Beatles">
                  <constructor-arg>
                         <list>
                                <value>Sgt. Pepper's Lonely Hearts Club Band</value>
                                <value>With a Little Help from My Friends</value>
                                <value>Lucy in the Sky with Diamonds</value>
                                <value>Getting Better</value>
                                <value>Fixing a Hole</value>
                                
                         </list>
                  </constructor-arg>
           </bean>
    </beans>

### 测试类 ###

#### CDPlayerTest.java： ####

package com.jiaobuchong.soundsystem;
    
    import com.jiaobuchong.config.CDConfig;
    import com.jiaobuchong.config.CDPlayerConfig;
    import com.jiaobuchong.dao.CompactDisc;
    import com.jiaobuchong.dao.MediaPlayer;
    import org.junit.Test;
    import org.junit.runner.RunWith;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.test.context.ContextConfiguration;
    import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
    
    /* CDPlayerTest takes advantage of Spring’s SpringJUnit4ClassRunner to have a Spring application context automatically created when the test starts. And the @Context-Configuration annotation tells it to load its configuration from the CDPlayerConfig class. */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = CDConfig.class)
    public class CDPlayerTest {
    
        @Autowired
        private MediaPlayer mediaPlayer;
    
        @Autowired
        @Qualifier("heyGirl")
        private CompactDisc keyGirl;
    
        @Autowired
        @Qualifier("compactDisc")
        private CompactDisc cd;
    
        @Test
        public void beanTest() {
            mediaPlayer.play();
            cd.play();
            keyGirl.play();
        }
    }

看完这个demo代码，基本上@Import和ImportResource的作用也就了然于胸了，以后妈妈再也不担心我的Spring配置了。更多细节请移步《Spring in Action 4th》。