桥接模式

Created2021-06-02Updated2021-06-03

桥接模式

  • 动机: 由于某些类型的固有的实现逻辑,使得它们具有两个变化的维度,乃至多个维度的变化
  • 将抽象部分(业务功能)与实现部分(平台实现)分离,使它们可以独立变化

代码例子

常见写法

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abstract class Messager {
    public abstract void login(String name);
    public abstract void sendMessage(String msg);
    public abstract void sendPicture(Image image);

    public abstract void playSound();
    public abstract void drawShape();
    public abstract void connect();
}

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//平台实现
abstract class PCMessagerBase extends Messager{
    @Override
    public abstract void playSound(){
       //......
    }
    @Override
    public abstract void drawShape();

    @Override
    public abstract void connect();
}

abstract class MobileMessagerBase extends Messager{
    @Override
    public abstract void playSound(){
       //......
    }
    @Override
    public abstract void drawShape();

    @Override
    public abstract void connect();
}
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//业务实现
class PCMessagerLite extends PCMessagerBase {
    @Override
    public void login(String name){
        super.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
        super.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
        super.drawShape();
        //...
    }
}

class PCMessagerPerfect extends PCMessagerBase {
    @Override
    public void login(String name){
        super.playSound)();
        //==================
        super.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
      super.playSound)();
        //==================
        super.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
      super.playSound)();
        //==================
        super.drawShape();
        //...
    }
}

class MobileMessagerLite extends MobileMessagerBase {
    @Override
    public void login(String name){
        super.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
        super.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
        super.drawShape();
        //...
    }
}

class MobileMessagerPerfect extends MobileMessagerBase {
    @Override
    public void login(String name){
        super.playSound)();
        //==================
        super.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
      super.playSound)();
        //==================
        super.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
      super.playSound)();
        //==================
        super.drawShape();
        //...
    }
}

桥接模式改良版本

  • 要点总结: Bridge模式使用”对象间的组合关系”解耦了抽象和现实之间固有的绑定关系,使得抽象和实现可以沿着各自的维度来变化.一般应用在”两个非常强的变化维度”,有时一个类也有多余两个的变化维度,这时可以使用Bridge模式扩展.
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    abstract class Messager {

        protected MessagerImpl msgImg;

        protected Messager(MessagerImpl msgImg){
            this.msgImg = msgImg;
        }

        public abstract void login(String name);
        public abstract void sendMessage(String msg);
        public abstract void sendPicture(Image image);
    }

    abstract class MessagerImpl {
        public abstract void playSound();
        public abstract void drawShape();
        public abstract void connect();
    }

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//平台实现
abstract class PCMessagerImpl extends MessagerImpl{
    @Override
    public abstract void playSound(){
       //......
    }
    @Override
    public abstract void drawShape();

    @Override
    public abstract void connect();
}

abstract class MobileMessagerImple extends MessagerImpl{
    @Override
    public abstract void playSound(){
       //......
    }
    @Override
    public abstract void drawShape();

    @Override
    public abstract void connect();
}
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//业务实现
class MessagerLite extends Messager {
    @Override
    public void login(String name){
        msgImg.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
        msgImg.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
        msgImg.drawShape();
        //...
    }
}

class MessagerPerfect extends Messager {
    @Override
    public void login(String name){
        msgImg.playSound)();
        //==================
        msgImg.connect();
        //.....
    }

    @Override
    public void sendMessage(String msg){
        msgImg.playSound)();
        //==================
        msgImg.drawShape();
        //...
    }

    @Override
    public void sendPicture(Image image){
        msgImg.playSound)();
        //==================
        msgImg.drawShape();
        //...
    }
}