设计模式五(桥接模式)

public interface DrawAPI {
   public void drawCircle(int radius, int x, int y);
}

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 +"]");
   }
}

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 +"]");
   }
}

public abstract class Shape {
   protected DrawAPI drawAPI;
   protected Shape(DrawAPI drawAPI){
      this.drawAPI = drawAPI;
   }
   public abstract void draw();  
}

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);
   }
}

public class BridgePatternDemo {
   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();
   }
}

核心是shape和子类。其中shape使用抽象类作为成员变量，后续运行代码时候父类引用子类的对象。并在子类对象用多态调用方法。