SPRING IN ACTION 第4版笔记-第二章-001-用@Autowired@ComponentScan、@Configuration、@Component实现自动装载bean

1.

package soundsystem;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration    //说明此类是配置文件
//@ComponentScan //开启扫描，会扫描当前类的包及其子包
//@ComponentScan(basePackages={"soundsystem", "video"})//扫描多个包
@ComponentScan(basePackageClasses={CDPlayer.class})//指定要扫描的类
public class CDPlayerConfig { 
}

2.

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

@Component
public class CDPlayer implements MediaPlayer {
  private CompactDisc cd;

  @Autowired
  public CDPlayer(CompactDisc cd) {  //依赖bean的id会叫"cd"???
    this.cd = cd;
  }

  public void play() {
    cd.play();
  }

}

3.

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

4.

package soundsystem;

import static org.junit.Assert.*;

import org.junit.Rule;
import org.junit.Test;
import org.junit.contrib.java.lang.system.StandardOutputStreamLog;
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)    //会自动创建applicationcontext
@ContextConfiguration(classes=CDPlayerConfig.class)//指定配置文件
public class CDPlayerTest {

  @Rule
  public final StandardOutputStreamLog log = new StandardOutputStreamLog();

  @Autowired
  private MediaPlayer player;  //默认id会是“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", 
        log.getLog());
  }

}

bean