创建型--桥接模式

分手后的思念是犯贱 2021-09-23 01:22 101阅读 0赞

## 概念 ##

--------------------

将抽象部分与其实现部分分离，使它们都可以独立的通过导出子类的方式进行扩充。

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：

1.  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。

## 举例 ##

--------------------

public class User1 {
    	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();
    		Shape blueCircle = new Circle(100,100, 10, new BlueCircle());	 
    		blueCircle.draw();
    		redCircle = new Circle2(100,100, 10, new BlueCircle());	
    		redCircle.draw();
    	}
    }
    //实现类的接口
    interface DrawAPI {
    	public void draw(int radius, int x, int y);
    }
    //实现类
    class RedCircle implements DrawAPI {
    	@Override
    	public void draw(int radius, int x, int y) {
    		System.out.println("Drawing Circle[ color: red, radius: "
    				+ radius +", x: " +x+", "+ y +"]");
    	}
    }
    class GreenCircle implements DrawAPI {
    	@Override
    	public void draw(int radius, int x, int y) {
    	    System.out.println("Drawing Circle[ color: green, radius: "
    	    		+ radius +", x: " +x+", "+ y +"]");
    	}
    }
    //抽象类
    abstract class Shape {
    	protected DrawAPI drawAPI;
    	protected Shape(DrawAPI drawAPI){
    		this.drawAPI = drawAPI;
    	}
    	public abstract void draw();  
    }
    //扩充抽象类
    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() {
    		//System.out.println("start draw");
    		drawAPI.draw(radius,x,y);
    		//System.out.println("ending draw");
    	}
    }
    //开始扩充
    //对实现类，增加蓝色Circle
    class BlueCircle implements DrawAPI {
    	@Override
    	public void draw(int radius, int x, int y) {
    		System.out.println("Drawing Circle[ color: Blue, radius: "
    				+ radius +", x: " +x+", "+ y +"]");
    	}
    }
    //生成抽象类的新子类，重写Circle的draw，使其更复杂
    class Circle2 extends Shape {
    	private int x, y, radius;
    	public Circle2(int x, int y, int radius, DrawAPI drawAPI) {
    		super(drawAPI);
    		this.x = x;  
    		this.y = y;  
    		this.radius = radius;
    	}
    	public void draw() {
    		System.out.println("start draw");
    		drawAPI.draw(radius,x,y);
    		System.out.println("ending draw");
    	}
    }
    
    Output:
    Drawing Circle[ color: red, radius: 10, x: 100, 100]
    Drawing Circle[ color: green, radius: 10, x: 100, 100]
    Drawing Circle[ color: Blue, radius: 10, x: 100, 100]
    start draw
    Drawing Circle[ color: Blue, radius: 10, x: 100, 100]
    ending draw