設計模式-享元模式

享元模式(Flyweight):能夠避免大量很是類似類的開銷。在程序設計中,有時須要生成大量細粒度的類實例來表示數據。若是能發現這些事例除了幾個參數外基本相同的，有時就可以大幅度的減小須要實例化的類的數量。java

若是能把哪些參數移到類事例的外面，在方法調用的時候將他們傳遞進來，就能夠經過共享大幅度的減小單個實例的數目ide

package com.fumeck.design.flyweight;

public abstract class FlyWeight {
    private String name;

    public FlyWeight(String name) {
        this.name = name;
    }

    public abstract void excute();
}

package com.fumeck.design.flyweight;

public class ConcreteFlyWeight extends FlyWeight{
    public ConcreteFlyWeight(String name) {
        super(name);
    }

    @Override
    public void excute() {
        //具體事件
    }
}

package com.fumeck.design.flyweight;

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

public class FlyWeightFactory {
    private Map<String, FlyWeight> map = new HashMap();

    public FlyWeight getFlyWeight(String name) {
        FlyWeight flyWeight = map.get(name);
        if (flyWeight != null) {
            return map.get(name);
        } else {
            flyWeight = new ConcreteFlyWeight(name);
            map.put("name", flyWeight);
            return flyWeight;
        }
    }
}