享元模式

享元模式（Flyweight Pattern）主要用于减少创建对象的数量，以减少内存占用和提高性能。

这种类型的设计模式属于结构型模式，它提供了减少对象数量从而改善应用所需的对象结构的方式。

享元模式尝试重用现有的同类对象，如果未找到匹配的对象，则创建新对象

实际案例

类信息概览：

类名 说明
Main.java 方法的总入口
RectangleFactory.java 工厂
Rectangle.java 长方形

定义

  • RectangleFactory.java
  [java]
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package com.ryo.design.pattern.note.flyweight;

import java.util.HashMap;
import java.util.Map;

/**
 * @author houbinbin
 * @version 1.0
 * @on 2017/8/12
 * @since 1.7
 */
public class RectangleFactory {

    private static Map<String, Rectangle> rectangleMap = new HashMap<>();

    public static Rectangle getRectangle(String color) {
          Rectangle rectangle = rectangleMap.get(color);

          if(rectangle == null) {
              rectangle = new Rectangle();
              rectangle.setColor(color);
              rectangleMap.put(color, rectangle);
          }
          return rectangle;
    }

}
  • Rectangle.java
  [java]
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package com.ryo.design.pattern.note.flyweight;

import lombok.Data;

/**
 * @author houbinbin
 * @version 1.0
 * @on 2017/8/12
 * @since 1.7
 */
@Data
public class Rectangle {

    private int width;

    private int weight;

    private String color;

}

测试

  • Main.java
  [java]
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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * Copyright (c) 2012-2018. houbinbini Inc.
 * design-pattern All rights reserved.
 */

package com.ryo.design.pattern.note.flyweight;

/**
 * <p> </p>
 *
 * <pre> Created: 2018/5/17 下午8:41  </pre>
 * <pre> Project: design-pattern  </pre>
 *
 * @author houbinbin
 * @version 1.0
 * @since JDK 1.7
 */
public class Main {

    public static void main(String[] args) {
        Rectangle rectangle = RectangleFactory.getRectangle("RED");
        rectangle.setWeight(11);
        Rectangle rectangle2 = RectangleFactory.getRectangle("BLUE");
        rectangle2.setWeight(12);
        Rectangle rectangle3 = RectangleFactory.getRectangle("YELLOW");
        rectangle3.setWeight(13);
        Rectangle rectangle4 = RectangleFactory.getRectangle("RED");
        rectangle4.setWeight(14);
        Rectangle rectangle5 = RectangleFactory.getRectangle("BLUE");
        rectangle5.setWeight(15);

        System.out.println(rectangle);
        System.out.println(rectangle2);
        System.out.println(rectangle3);
        System.out.println(rectangle4);
        System.out.println(rectangle5);
    }

}
  • 测试结果
  [plaintext]
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Rectangle(width=0, weight=14, color=RED)
Rectangle(width=0, weight=15, color=BLUE)
Rectangle(width=0, weight=13, color=YELLOW)
Rectangle(width=0, weight=14, color=RED)
Rectangle(width=0, weight=15, color=BLUE)

实现方式

UML & Code

UML

UML 图示如下

Code

代码地址

享元模式

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