1 享元模式

1.1 概念

1、定义

运用共享技术有效地支持大量细粒度的对象。

2、优点

如果系统有大量类似的对象，可以节省大量的内存及CPU资源。

3、应用

JDK源码：String、Integer、Long……

1.2 实现

package com.xianhuii.designpattern.flyweight;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class Flyweight {
    public static void main(String[] args) {
        TreeNode treeNode1 = new TreeNode(0, 4, TreeFactory.getTree("xxx", "xxxxxx"));
        TreeNode treeNode2 = new TreeNode(1, 4, TreeFactory.getTree("xxx", "xxxxxx"));
        TreeNode treeNode3 = new TreeNode(2, 4, TreeFactory.getTree("yyy", "xxxxxx"));
        TreeNode treeNode4 = new TreeNode(3, 4, TreeFactory.getTree("yyy", "xxxxxx"));
    }
}

class TreeNode {
    private int x;
    private int y;
    private Tree tree;

    public TreeNode(int x, int y, Tree tree) {
        this.x = x;
        this.y = y;
        this.tree = tree;
    }

    public int getX() {
        return x;
    }

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

    public int getY() {
        return y;
    }

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

    public Tree getTree() {
        return tree;
    }

    public void setTree(Tree tree) {
        this.tree = tree;
    }
}

class TreeFactory {
    private static Map<String, Tree> map = new ConcurrentHashMap<>();

    public static Tree getTree(String name, String data) {
        if (map.containsKey(name)) {
            return map.get(name);
        }
        Tree tree = new Tree(name, data);
        map.put(name, tree);
        return tree;
    }
}

class Tree {
    private final String name;
    private final String data;

    public Tree(String name, String data) {
        System.out.println("name：" + name + " created");
        this.name = name;
        this.data = data;
    }

    public String getName() {
        return name;
    }

    public String getData() {
        return data;
    }
}