适配器模式

1、简介

适配器(Adapater Pattern)作为二个不兼容接口的桥梁。
例如：内存卡 -> 读卡器 -> 电脑硬盘

简单来说，就是将一个类的接口转换为客户希望的另一个接口，使得原本因为接口不兼容的那些类可以一起工作。

关键思想: 继承或者依赖已有的对象，实现想要的目标接口

2、使用

// 高级播放器接口
public interface AdvenceMediaPlayer {
	
	void playMp4(String fileName);
	
	void playMp5(String fileName);
}
// 普通播放器接口
public interface MediaPlayer {

	void play(String audioType, String fileName);
}

// 适配器类
public class MediaAdapter implements MediaPlayer{

	private AdvenceMediaPlayer advenceMediaPlayer;
	
	public MediaAdapter(String audioType) {
		if(audioType.equalsIgnoreCase("mp4")) {
			advenceMediaPlayer = new Mp4Player();
		}else if(audioType.equalsIgnoreCase("mp5")) {
			advenceMediaPlayer = new Mp5Player();
		}
	}
		
	@Override
	public void play(String audioType, String fileName) {
		if(audioType.equalsIgnoreCase("mp4")) {
			advenceMediaPlayer.playMp4(fileName);
		}else if(audioType.equalsIgnoreCase("mp5")) {
			advenceMediaPlayer.playMp5(fileName);
		}
	}
}
// mp4
public class Mp4Player implements AdvenceMediaPlayer{

	@Override
	public void playMp4(String fileName) {
		System.out.println("Mp4 player play "+fileName);
	}
	
	@Override
	public void playMp5(String fileName) {
		
	}
}
// mp5
public class Mp5Player implements AdvenceMediaPlayer{

	@Override
	public void playMp4(String fileName) {
		
	}
	
	@Override
	public void playMp5(String fileName) {
		System.out.println("Mp5 player play "+fileName);
	}
}
// mp3
public class AudioPlayer implements MediaPlayer{

	private MediaAdapter adapter;
	
	@Override
	public void play(String audioType, String fileName) {
		if(audioType.equalsIgnoreCase("mp3")) {
			System.out.println("mp3 play "+fileName);
		}else if(audioType.equalsIgnoreCase("mp4")
				|| audioType.equalsIgnoreCase("mp5")) {
			adapter = new MediaAdapter(audioType);
			adapter.play(audioType, fileName);
		}else {
			System.out.println("Invalid mediatype"+audioType+" not support!");
		}
	}
}
// 测试
/* 适配器模式 */
		AudioPlayer player = new AudioPlayer();
		player.play("mp3", "空");
		player.play("mp4", "空");
		player.play("mp5", "空");
		player.play("mp6", "空");