我們將創(chuàng)建一個(gè) Shape 接口和實(shí)現(xiàn)了 Shape 接口的實(shí)體類。然后我們創(chuàng)建一個(gè)實(shí)現(xiàn)了 Shape 接口的抽象裝飾類ShapeDecorator，并把 Shape 對(duì)象作為它的實(shí)例變量。

RedShapeDecorator 是實(shí)現(xiàn)了 ShapeDecorator 的實(shí)體類。

DecoratorPatternDemo，我們的演示類使用 RedShapeDecorator 來裝飾 Shape 對(duì)象。

步驟 1

創(chuàng)建一個(gè)接口。

Shape.java

public interface Shape {
  void draw();
}

步驟 2

創(chuàng)建實(shí)現(xiàn)接口的實(shí)體類。

Rectangle.java

public class Rectangle implements Shape {
 
  @Override
  public void draw() {
   System.out.println("Shape: Rectangle");
  }
}

Circle.java

public class Circle implements Shape {
 
  @Override
  public void draw() {
   System.out.println("Shape: Circle");
  }
}

步驟 3

創(chuàng)建實(shí)現(xiàn)了 Shape 接口的抽象裝飾類。

ShapeDecorator.java

public abstract class ShapeDecorator implements Shape {
  protected Shape decoratedShape;
 
  public ShapeDecorator(Shape decoratedShape){
   this.decoratedShape = decoratedShape;
  }
 
  public void draw(){
   decoratedShape.draw();
  }  
}

步驟 4

創(chuàng)建擴(kuò)展自 ShapeDecorator 類的實(shí)體裝飾類。

RedShapeDecorator.java

public class RedShapeDecorator extends ShapeDecorator {
 
  public RedShapeDecorator(Shape decoratedShape) {
   super(decoratedShape);    
  }
 
  @Override
  public void draw() {
   decoratedShape.draw();     
   setRedBorder(decoratedShape);
  }
 
  private void setRedBorder(Shape decoratedShape){
   System.out.println("Border Color: Red");
  }
}

步驟 5

使用 RedShapeDecorator 來裝飾 Shape 對(duì)象。

DecoratorPatternDemo.java

public class DecoratorPatternDemo {
  public static void main(String[] args) {
 
   Shape circle = new Circle();
 
   Shape redCircle = new RedShapeDecorator(new Circle());
 
   Shape redRectangle = new RedShapeDecorator(new Rectangle());
   System.out.println("Circle with normal border");
   circle.draw();
 
   System.out.println("\nCircle of red border");
   redCircle.draw();
 
   System.out.println("\nRectangle of red border");
   redRectangle.draw();
  }
}

步驟 6

驗(yàn)證輸出。

Circle with normal border
Shape: Circle

Circle of red border
Shape: Circle
Border Color: Red

Rectangle of red border
Shape: Rectangle
Border Color: Red

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