package soundsystem;

public interface CompactDisc {
 void play();
}

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);
 }
 
}

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

@Configuration
@ComponentScan
public class CDPlayerConfig { 
}

<?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:context="http://www.springframework.org/schema/context";
 xmlns:c="http://www.springframework.org/schema/c";
 xmlns:p="http://www.springframework.org/schema/p";
 xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsd">;

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

</beans>

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)
@ContextConfiguration(classes=CDPlayerConfig.class)
public class CDPlayerTest {

 @Rule
 public final StandardOutputStreamLog log = new StandardOutputStreamLog();
 
 @Autowired
 private CompactDisc cd;
 
 @Test
 public void cdShouldNotBeNull() {
  assertNotNull(cd);
 }

}

@Component("lonelyHeartsClub")
public class SgtPeppers implements CompactDisc {
 
}

@Configuration
@ComponentScan("soundsystem")
public class CDPlayerConfig { 
}

@Configuration
@ComponentScan(basePackages="soundsystem")
public class CDPlayerConfig { 
}

@Configuration
@ComponentScan(basePackages={"soundsystem", "voice"})
public class CDPlayerConfig { 
}

@Configuration
@ComponentScan(basePackegeClasses={CDPlayer.class, DVDPlayer.class})
public class CDPlayerConfig { 
}

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) {
  this.cd = cd;
 }

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

}

@Autowried注解不仅能够用在构造器上，还能用在Setter方法上。
@Autowired
public void setCompactDisc(CompactDisc cd) {
  this.cd = cd;
}

@Autowired(required=false)
public CDPlayer(CompactDisc cd) {
  this.cd = cd;
}

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)
@ContextConfiguration(classes=CDPlayerConfig.class)
public class CDPlayerTest {

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

 @Autowired
 private MediaPlayer 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\n", 
    log.getLog());
 }

}