package com.interview.design.pattern.structural;
/**
* Created_By: stefanie
* Date: 14-12-3
* Time: 上午10:46
*
* Adapter pattern works as a bridge between two incompatible interfaces.
*/
public class AdapterPattern {
/**
* Need to create a MediaPlayer play mp3, mp4 and vlc.
* 1. Haven't another interface of AdvancedMediaPlayer could play vlc and mp4, but the interface is not incompatible.
* 2. Use MediaAdapter to convert the interface, MediaAdapter composite a AdvancedMediaPlayer , and change the interface to play
*/
static class ClassAdapterPattern{
static interface MediaPlayer {
public void play(String audioType, String fileName);
}
static interface AdvancedMediaPlayer {
public void playVlc(String fileName);
public void playMp4(String fileName);
}
static class VlcPlayer implements AdvancedMediaPlayer{
@Override
public void playVlc(String fileName) {
System.out.println("Playing vlc file. Name: "+ fileName);
}
@Override
public void playMp4(String fileName) {
//do nothing
}
}
static class Mp4Player implements AdvancedMediaPlayer{
@Override
public void playVlc(String fileName) {
//do nothing
}
@Override
public void playMp4(String fileName) {
System.out.println("Playing mp4 file. Name: "+ fileName);
}
}
/**
* adapt AdvancedMediaPlayer's interface to play as MediaPlayer
*/
static 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();
}
}
@Override
public void play(String audioType, String fileName) {
if(audioType.equalsIgnoreCase("vlc")){
advancedMusicPlayer.playVlc(fileName);
}else if(audioType.equalsIgnoreCase("mp4")){
advancedMusicPlayer.playMp4(fileName);
}
}
}
static class AudioPlayer implements MediaPlayer {
MediaAdapter mediaAdapter;
@Override
public void play(String audioType, String fileName) {
//inbuilt support to play mp3 music files
if(audioType.equalsIgnoreCase("mp3")){
System.out.println("Playing mp3 file. Name: "+ fileName);
}
//mediaAdapter is providing support to play other file formats
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 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");
}
}
/**
* 接口的适配器是这样的：有时我们写的一个接口中有多个抽象方法，当我们写该接口的实现类时，
* 必须实现该接口的所有方法，这明显有时比较浪费，因为并不是所有的方法都是我们需要的，
* 有时只需要某一些，此处为了解决这个问题，我们引入了接口的适配器模式，借助于一个抽象类，
* 该抽象类实现了该接口，实现了所有的方法，而我们不和原始的接口打交道，只和该抽象类取得联系，
* 所以我们写一个类，继承该抽象类，重写我们需要的方法就行。
*/
static class InterfaceAdapter{
static interface AdvancedMediaPlayer {
public void playVlc(String fileName);
public void playMp4(String fileName);
}
/**
* create a Base class give the basic implementation
* and the sub-class doesn't need to implement un-necessary method
*/
static class AdvancedMediaPlayerBase implements AdvancedMediaPlayer{
@Override
public void playVlc(String fileName) {
}
@Override
public void playMp4(String fileName) {
}
}
static class VlcPlayer extends AdvancedMediaPlayerBase{
@Override
public void playVlc(String fileName) {
System.out.println("Playing vlc file. Name: "+ fileName);
}
}
static class Mp4Player extends AdvancedMediaPlayerBase{
@Override
public void playMp4(String fileName) {
System.out.println("Playing mp4 file. Name: "+ fileName);
}
}
}
}