Object Adapter概述

Object Adapter - 图1

玩具代码案例 - 电源插座

目标接口的调用者

如何将一个中国的2口插头兼容这个美国的3口插座

Usa3PinSocket 三口插头

  1. package org.gof.structural.patterns1.adapter.objectadapter.socket;
  3. import org.gof.structural.patterns1.adapter.objectadapter.plug.api.IUsa3PinPlug;
  5. public class Usa3PinSocket {
  7.     public void play(IUsa3PinPlug usa3PinPlug) {
  8.         usa3PinPlug.runUsa3Pin();
  9.     }
  11.     // 破坏掉已有的组件, 强行提供对新接口的支持，但是如果这个类不是我们能够修改的代码，情况就有些不一样
  12. /*    public void play(IChina2PinPlug china2PinPlug) {
  13.         china2PinPlug.runChina2Pin();
  14.     }*/
  15. }

适配与被适配的类型

IChina2PinPlug 两口插头

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api;
  3. public interface IChina2PinPlug {
  5.     public void runChina2Pin();
  6. }

China2PinPlug

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.impl;
  3. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IChina2PinPlug;
  5. public class China2PinPlug implements IChina2PinPlug {
  7.     @Override
  8.     public void runChina2Pin() {
  9.         System.out.println("I am china 2 pin plug, running");
  10.     }
  11. }

IUsa3PinPlug

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api;
  3. public interface IUsa3PinPlug {
  5.     public void runUsa3Pin();
  6. }

Usa3PinPlug

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.impl;
  3. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IUsa3PinPlug;
  5. public class Usa3PinPlug implements IUsa3PinPlug {
  7.     @Override
  8.     public void runUsa3Pin() {
  9.         System.out.println("I am usa 2 pin plug, running");
  10.     }
  11. }

对象适配器类型

China2PinPlugToUsa3PinPlugAdapter

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.adpter;
  3. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IChina2PinPlug;
  4. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IUsa3PinPlug;
  6. public class China2PinPlugToUsa3PinPlugAdapter implements IUsa3PinPlug {
  8.     // 包装一个被适配的对象
  9.     private IChina2PinPlug china2PinPlug;
  11.     public China2PinPlugToUsa3PinPlugAdapter(IChina2PinPlug china2PinPlug) {
  12.         this.china2PinPlug = china2PinPlug;
  13.     }
  15.     @Override
  16.     public void runUsa3Pin() {
  17.         china2PinPlug.runChina2Pin();
  18.     }
  19. }

不基于对象适配器模式的实现

Main

  1. package org.gof.structural.patterns1.adapter.objectadapter.app.bad;
  3. import org.gof.structural.patterns1.adapter.objectadapter.plug.api.IChina2PinPlug;
  4. import org.gof.structural.patterns1.adapter.objectadapter.plug.api.IUsa3PinPlug;
  5. import org.gof.structural.patterns1.adapter.objectadapter.plug.impl.China2PinPlug;
  6. import org.gof.structural.patterns1.adapter.objectadapter.plug.impl.Usa3PinPlug;
  7. import org.gof.structural.patterns1.adapter.objectadapter.socket.Usa3PinSocket;
  9. public class Main {
  10.     public static void main(String[] args) {
  11.         Usa3PinSocket usa3PinSocket = new Usa3PinSocket();
  13.         IUsa3PinPlug usa3PinPlug = new Usa3PinPlug();
  14.         usa3PinSocket.play(usa3PinPlug);
  16.         IChina2PinPlug china2PinPlug = new China2PinPlug();
  17.         // 当前插座不支持该接口
  18.         //usa3PinSocket.play(china2PinPlug);
  19.     }
  20. }

基于对象适配器模式的实现

Main

  1. package online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.app.good;
  3. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.adpter.China2PinPlugToUsa3PinPlugAdapter;
  4. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IChina2PinPlug;
  5. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.api.IUsa3PinPlug;
  6. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.impl.China2PinPlug;
  7. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.impl.Usa3PinPlug;
  8. import online.javabook.gof.structural.patterns1.adapter.objectadapter.plug.socket.Usa3PinSocket;
  10. public class Main {
  11.     public static void main(String[] args) {
  12.         Usa3PinSocket usa3PinSocket = new Usa3PinSocket();
  14.         IUsa3PinPlug usa3PinPlug = new Usa3PinPlug();
  15.         usa3PinSocket.play(usa3PinPlug);
  17.         IChina2PinPlug china2PinPlug = new China2PinPlug();
  18.         // 通过对象适配器兼容已有接口
  19.         IUsa3PinPlug adapter = new China2PinPlugToUsa3PinPlugAdapter(china2PinPlug);
  20.         usa3PinSocket.play(adapter);
  21.     }
  22. }

Console

  1. I am usa 2 pin plug, running
  2. I am china 2 pin plug, running