Java语言设计模式之桥接（Bridge）模式

Bridge 模式的目的就是为了结构化你的代码，从而使得你可以很容易的添加新类型的前端（front-end）对象(这些前端对象是通过调用新类型的后端（back-end）对象的功能实现的)。这么一来，就可以对前端(front-end)和后端(back-end)互不干扰地进行修改。

通过使用 Bridge 模式，你可以避免（类）组合所带来的类的数目的爆炸省增长。但是别忘了 Bridge 模式所处理的一系列变化通常都是发生在编码阶段：当为了实现某个功能而必须处理越来越多的选项（options）时，Bridge 模式可以使你的代码保持条例性。

Bridge 模式实例：

BridgeStructure .java

package com.enfo.wd.mode;class Abstraction{    private Implementation implementation;    public Abstraction(Implementation imp){        implementation=imp;    }    public void service1(){        implementation.facility1();        implementation.facility2();    }    public void service2(){        implementation.facility2();        implementation.facility3();    }    public void service3(){        implementation.facility1();        implementation.facility2();        implementation.facility4();    }    public Implementation getImplementation(){        return implementation;    }}class ClientService1 extends Abstraction{    public ClientService1(Implementation imp){super(imp);}    public void serviceA(){        service1();        service2();    }    public void serviceB(){        service3();    }}class ClientService2 extends Abstraction{    public ClientService2(Implementation imp){super(imp);}    public void serviceC(){        service2();        service3();    }    public void serviceD(){        service1();        service3();    }    public void serviceE(){        getImplementation().facility3();    }}interface Implementation{    void facility1();    void facility2();    void facility3();    void facility4();}class Library1{    public void method1(){        System.out.println("Library1.method1()");    }    public void method2(){        System.out.println("Library1.method2()");    }}class Library2{    public void operation1(){        System.out.println("Library2.operation1()");    }    public void operation2(){        System.out.println("Library2.operation2()");    }    public void operation3(){        System.out.println("Library2.operation3()");    }}class Implementation1 implements Implementation{    private Library1 delegate=new Library1();    @Override    public void facility1() {        System.out.println("Implementation1.facility1()");        delegate.method1();    }    @Override    public void facility2() {        System.out.println("Implementation1.facility2()");        delegate.method2();    }    @Override    public void facility3() {        System.out.println("Implementation1.facility3()");        delegate.method2();        delegate.method1();    }    @Override    public void facility4() {        System.out.println("Implementation1.facility4()");        delegate.method1();    }}class Implementation2 implements Implementation{    private Library2 delegate=new Library2();    @Override    public void facility1() {        System.out.println("Implementation2.facility1()");        delegate.operation1();    }    @Override    public void facility2() {        System.out.println("Implementation2.facility2()");        delegate.operation2();    }    @Override    public void facility3() {        System.out.println("Implementation2.facility3()");        delegate.operation3();    }    @Override    public void facility4() {        System.out.println("Implementation2.facility4()");        delegate.operation1();    }}public class BridgeStructure {    public void test1(){        ClientService1 cs1=new ClientService1(new Implementation1());        cs1.serviceA();        cs1.serviceB();    }    public void test2(){        ClientService1 cs1=new ClientService1(new Implementation2());        cs1.serviceA();        cs1.serviceB();    }    public void test3(){        ClientService2 cs2=new ClientService2(new Implementation1());        cs2.serviceC();        cs2.serviceD();        cs2.serviceE();    }    public void test4(){        ClientService2 cs2=new ClientService2(new Implementation2());        cs2.serviceC();        cs2.serviceD();        cs2.serviceE();    }    public static void main(String[] args){        BridgeStructure tructur=new BridgeStructure();        tructur.test1();        tructur.test2();        tructur.test3();        tructur.test4();    }}