Matlab享元模式

享元模式(Flyweight)通过共享技术实现相同或相似对象的重用，可以减少创建对象的数量，以减少内存占用和提高性能。Java String的常量池，python logging，线程池，数据库连接池都用到了享元模式。享元模式与单例模式类似，都具有共享变量的特征。本文通过使用matlab语言对享元模式进行实现。

IFlyweight.m

classdef IFlyweight < handle
    methods(Abstract)
        print(~);
    end
end

Flyweight.m

classdef Flyweight < IFlyweight
    properties
        color
    end
    methods
        function obj = Flyweight(color)
            obj.color =  color;
        end
        function print(obj)
            disp("color:"+obj.color)
        end
    end
end

FlyweightFactory.m

classdef FlyweightFactory < handle
    methods(Static)
        function res = getFlyweightMap()
            persistent flyweightMap;
            if isempty(flyweightMap) || ~isvalid(flyweightMap)
                flyweightMap = containers.Map();
            end
            res = flyweightMap;
        end
        function obj = getFlyweight(color)
            flyweightMap = FlyweightFactory.getFlyweightMap();
            if(~flyweightMap.isKey(color))
                flyweightMap(color) = Flyweight(color);
            end
            obj = flyweightMap(color);
        end
        function size = getFlyweightMapSize()
            flyweightMap = FlyweightFactory.getFlyweightMap();
            size = flyweightMap.length();
        end
    end
end

测试代码

fw1 = FlyweightFactory.getFlyweight('Red');
fw2 = FlyweightFactory.getFlyweight('Blue');
fw3 = FlyweightFactory.getFlyweight('Red');
fw1.print();
fw2.print();
fw3.print();
disp(FlyweightFactory.getFlyweightMapSize());
clear('FlyweightFactory');