一、适配器模式定义

别名： 门面模式
类型： 结构型模式
目的： 将不兼容的接口 通过适配器 转换成可兼容的接口。

二、例子

2.1 菜鸟教程例子

2.1.1 定义两个不兼容的播放接口MediaPlayer 、AdvancedMediaPlayer

public interface MediaPlayer {public void play(String audioType, String fileName);
}

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

2.1.2 定义AdvancedMediaPlayer两个实现类VlcPlayer 、Mp4Player

VlcPlayer

public class VlcPlayer implements AdvancedMediaPlayer{@Overridepublic void playVlc(String fileName) {System.out.println("Playing vlc file. Name: "+ fileName);      }@Overridepublic void playMp4(String fileName) {//什么也不做}
}

Mp4Player

public class Mp4Player implements AdvancedMediaPlayer{@Overridepublic void playVlc(String fileName) { //什么也不做 }@Overridepublic void playMp4(String fileName) {System.out.println("Playing mp4 file. Name: "+ fileName);      }
}

2.1.3 定义适配器MediaAdapter

将AdvancedMediaPlayer 接口适配MediaPlayer 接口

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

2.1.4 定义AudioPlayer 并使用MediaAdapter

public class AudioPlayer implements MediaPlayer {MediaAdapter mediaAdapter; @Overridepublic void play(String audioType, String fileName) {    //播放 mp3 音乐文件的内置支持if(audioType.equalsIgnoreCase("mp3")){System.out.println("Playing mp3 file. Name: "+ fileName);         } //mediaAdapter 提供了播放其他文件格式的支持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");}}   
}

2.1.5 使用

public class AdapterPatternDemo {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");}
}

2.2 JDK源码——InputStreamReader

InputStream接口适配Reader接口

public abstract class Reader implements Readable, Closeable {public int read(CharBuffer target) throws IOException {if (target.isReadOnly())throw new ReadOnlyBufferException();int nread;if (target.hasArray()) {char[] cbuf = target.array();int pos = target.position();int rem = Math.max(target.limit() - pos, 0);int off = target.arrayOffset() + pos;nread = this.read(cbuf, off, rem);if (nread > 0)target.position(pos + nread);} else {int len = target.remaining();char[] cbuf = new char[len];nread = read(cbuf, 0, len);if (nread > 0)target.put(cbuf, 0, nread);}return nread;}}

public class InputStreamReader extends Reader {private final StreamDecoder sd;public InputStreamReader(InputStream in) {super(in);Charset cs = Charset.defaultCharset();sd = StreamDecoder.forInputStreamReader(in, lockFor(this), cs);}public int read(CharBuffer target) throws IOException {return sd.read(target);}
}

2.3 Spring源码——AdvisorAdapter

切面适配器接口。

Advisor适配MethodInterceptor 接口

public interface AdvisorAdapter {boolean supportsAdvice(Advice advice);MethodInterceptor getInterceptor(Advisor advisor);
}

实现类MethodBeforeAdviceAdapter

class MethodBeforeAdviceAdapter implements AdvisorAdapter, Serializable {MethodBeforeAdviceAdapter() {}public boolean supportsAdvice(Advice advice) {return advice instanceof MethodBeforeAdvice;}public MethodInterceptor getInterceptor(Advisor advisor) {MethodBeforeAdvice advice = (MethodBeforeAdvice)advisor.getAdvice();return new MethodBeforeAdviceInterceptor(advice);}
}

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三、其他设计模式

创建型模式
结构型模式

• 1、设计模式——装饰器模式（Decorator Pattern）+ Spring相关源码

行为型模式

• 1、设计模式——访问者模式（Visitor Pattern）+ Spring相关源码
• 2、设计模式——中介者模式（Mediator Pattern）+ JDK相关源码
• 3、设计模式——策略模式（Strategy Pattern）+ Spring相关源码
• 4、设计模式——状态模式（State Pattern）
• 5、设计模式——命令模式（Command Pattern）+ Spring相关源码
• 6、设计模式——观察者模式（Observer Pattern）+ Spring相关源码
• 7、设计模式——备忘录模式（Memento Pattern）
• 8、设计模式——模板方法模式（Template Pattern）+ Spring相关源码
• 9、设计模式——迭代器模式（Iterator Pattern）+ Spring相关源码
• 10、设计模式——责任链模式（Chain of Responsibility Pattern）+ Spring相关源码
• 11、设计模式——解释器模式（Interpreter Pattern）+ Spring相关源码