Java实现(06)——适配器模式(Adapter Pattern)

适配器模式用于连接两个不兼容的接口，生活中的一个例子就是笔记本需要通过读卡器读取内存卡中的数据，读卡器就相当于适配器。

本例中使用MediaAdapter继承MediaPlayer接口，同时使用AdvancedMediaPlayer中类的对象。



public interface AdvanceMediaPlayer {
public void playVlc(String fileName);
public void playMp4(String fileName);
}

public class Mp4Player implements AdvanceMediaPlayer {

@Override
public void playVlc(String fileName) {
// do nothing
}

@Override
public void playMp4(String fileName) {
System.out.println("Playing mp4 file. Name: " + fileName);
}
}

public class VlcPlayer implements AdvanceMediaPlayer {
@Override
public void playVlc(String fileName) {
System.out.println("Playing vlc file. Name: " + fileName);
}

@Override
public void playMp4(String fileName) {
// do nothing
}
}

public class MediaAdapter implements MediaPlayer {
AdvanceMediaPlayer advanceMediaPlayer;
public MediaAdapter(String audioType) {
if (audioType.equalsIgnoreCase("vlc")) {
advanceMediaPlayer = new VlcPlayer();
} else if (audioType.equalsIgnoreCase("mp4")) {
advanceMediaPlayer = new Mp4Player();
}
}
@Override
public void play(String audioType, String fileName) {
if (audioType.equalsIgnoreCase("vlc")) {
advanceMediaPlayer.playVlc(fileName);
} else if (audioType.equalsIgnoreCase("mp4")) {
advanceMediaPlayer.playMp4(fileName);
}
}
}

public class AudioPlayer implements MediaPlayer {
MediaPlayer mediaAdapter;
@Override
public void play(String audioType, String fileName) {
if (audioType.equalsIgnoreCase("mp3")) {
System.out.println("Playing mp3 file. Name: " + fileName);
} else if (audioType.equalsIgnoreCase("vlc") || audioType.equalsIgnoreCase("mp4")) {
mediaAdapter = new MediaAdapter(audioType);
mediaAdapter.play(audioType, fileName);
} else {
System.out.println("Invalid media. " + audioType + " format not supported");
}
}
}

public class Demo {
public static void main(String[] args) {
AudioPlayer audioPlayer = new AudioPlayer();
audioPlayer.play("mp3", "beyond the horizon.mp3");
audioPlayer.play("mp4", "alone.mp4");
audioPlayer.play("vlc", "far far away.vlc");
audioPlayer.play("avi", "mind me.avi");
}
}

输出：
Playing mp3 file. Name: beyond the horizon.mp3

Playing mp4 file. Name: alone.mp4

Playing vlc file. Name: far far away.vlc

Invalid media. avi format not supported

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