2. 结构型模式 (5) 桥接模式

2. 结构型模式 (5) 桥接模式

桥接（Bridge）是通过提供抽象化和实现化之间的桥接结构，来实现二者的解耦，使得二者可以独立变化。

将抽象部分与实现部分分离，使它们都可以独立的变化。

优点：
1. 抽象和实现的分离。
2. 优秀的扩展能力。
3. 实现细节对客户透明。
缺点：
桥接模式的引入会增加系统的理解与设计难度，由于聚合关联关系建立在抽象层，要求开发者针对抽象进行设计与编程。

1. 桥接模式

package com.andrew.pattern0205.bridge.model01;
public interface DrawAPI {
    public void drawCircle(int radius, int x, int y);
}

package com.andrew.pattern0205.bridge.model01;
public class RedCircle implements DrawAPI {
    @Override
    public void drawCircle(int radius, int x, int y) {
        System.out.println("Drawing Circle[ color: red, radius: " + radius +", x: " +x+", "+ y +"]");
    }
}

package com.andrew.pattern0205.bridge.model01;
public class GreenCircle implements DrawAPI {
    @Override
    public void drawCircle(int radius, int x, int y) {
        System.out.println("Drawing Circle[ color: green, radius: " + radius +", x: " +x+", "+ y +"]");
    }
}

package com.andrew.pattern0205.bridge.model01;
public abstract class Shape {
    protected DrawAPI drawAPI;
    protected Shape(DrawAPI drawAPI) {
        this.drawAPI = drawAPI;
    }
    public abstract void draw();
}

package com.andrew.pattern0205.bridge.model01;
public class Circle extends Shape {
    private int x, y, radius;
    public Circle(int x, int y, int radius, DrawAPI drawAPI) {
        super(drawAPI);
          this.x = x;  
          this.y = y;  
          this.radius = radius;
    }
    public void draw() {
        drawAPI.drawCircle(radius,x,y);
    }
}

package com.andrew.pattern0205.bridge.model01;
/**
 * 1. 桥接模式
 * 
 * @author andrew
 * @date 2018/07/15
 */
public class Client {
    public static void main(String[] args) {
        Shape redCircle = new Circle(100,100, 10, new RedCircle());
        Shape greenCircle = new Circle(100,100, 10, new GreenCircle());
        redCircle.draw();
        greenCircle.draw();
    }
}
运行结果：
Drawing Circle[ color: red, radius: 10, x: 100, 100]
Drawing Circle[ color: green, radius: 10, x: 100, 100]