享元模式

以下是享元模式的简介

//Shape.java
public interface Shape {
  void draw();
}

//Circle.java
public class Circle implements Shape {
  private String color;
  private int x;
  private int y;
  private int radius;

  public Circle(String color){
     this.color = color;     
  }

  public void setX(int x) {
     this.x = x;
  }

  public void setY(int y) {
     this.y = y;
  }

  public void setRadius(int radius) {
     this.radius = radius;
  }

  @Override
  public void draw() {
     System.out.println("Circle: Draw() [Color : " + color 
        +", x : " + x +", y :" + y +", radius :" + radius);
  }
}

//ShapeFactory.java
import java.util.HashMap;

public class ShapeFactory {
  private static final HashMap<String, Shape> circleMap = new HashMap<>();

  public static Shape getCircle(String color) {
     Circle circle = (Circle)circleMap.get(color);

     if(circle == null) {
        circle = new Circle(color);
        circleMap.put(color, circle);
        System.out.println("Creating circle of color : " + color);
     }
     return circle;
  }
}


//FlyweightPatternDemo.java
public class FlyweightPatternDemo {
  private static final String colors[] = 
     { "Red", "Green", "Blue", "White", "Black" };
  public static void main(String[] args) {

     for(int i=0; i < 20; ++i) {
        Circle circle = 
           (Circle)ShapeFactory.getCircle(getRandomColor());
        circle.setX(getRandomX());
        circle.setY(getRandomY());
        circle.setRadius(100);
        circle.draw();
     }
  }
  private static String getRandomColor() {
     return colors[(int)(Math.random()*colors.length)];
  }
  private static int getRandomX() {
     return (int)(Math.random()*100 );
  }
  private static int getRandomY() {
     return (int)(Math.random()*100);
  }
}
   ```