Spring 依賴注入(JAVA)

配置类

CDPlayerConfig.java

 

package soundsystem;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class CDPlayerConfig {

    @Bean
    public CompactDisc sgtPeppers() {
        return new SgtPeppers();
    }
    
    @Bean
    public CDPlayer cdPlayer() {
        return new CDPlayer(sgtPeppers());
    }
}

 

 

CD播放器类：

CDPlayer.java

 

package soundsystem;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class CDPlayer {
    private CompactDisc cd;
    
    @Autowired
    public CDPlayer(CompactDisc cd) {
        this.cd = cd;
    }
    
    public void play() {
        cd.play();
    }
}

 

CD接口：

 

CompactDisc.java

 

package soundsystem;

public interface CompactDisc {
    void play();
}

 

CD实现类：

 

SgtPeppers.java

 

package soundsystem;

import org.springframework.stereotype.Component;

@Component
public class SgtPeppers implements CompactDisc {

    private String title = "Sgt. Pepper's Lonely Hearts Club Band";
    private String artist = "The Beatles";
    
    private String test;

    public void play() {
        System.out.println("Playing " + title + " by " + artist);
    }

    public String getTest() {
        return test;
    }

    public void setTest(String test) {
        this.test = test;
    }

}

 

 

测试类

CDPlayerTest.java

package soundsystem;

import static org.junit.Assert.*;

import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.SystemOutRule;
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;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes=CDPlayerConfig.class)
public class CDPlayerTest {
    
    @Rule
    public final SystemOutRule log = 
        new SystemOutRule().enableLog();

    @Autowired
    private CDPlayer player;

    @Autowired
    private CompactDisc cd;

    @Test
    public void cdShouldNotBeNull() {
        assertNotNull(cd);
    }
    
    @Test
    public void play() {
        player.play();

        assertEquals(
            "Playing Sgt. Pepper's Lonely Hearts Club Band by The Beatles\r\n",
            log.getLog());
    }
}