结构型模式-享元模式

　　享元模式是对耗资源的对象创建采取事先创建，再使用的一种方式，持有一组对象，要用时先从这一组对象中寻找，找不到再重新创建，通常结合工厂模式创建对象

　　享元对象区分了内部状态(Intrinsic State)和外部状态(Extrinsic State)

　　内部状态是存储在享元对象内部并且不会随环境改变而改变的状态，内部状态可以共享。

　　外部状态是随环境改变而改变的、不可以共享的状态。

package constructional.pattern.flyweight; public abstract class Flyweight { public abstract void operation(); } package constructional.pattern.flyweight; public class ConcreteFlyweight extends Flyweight{ private String string; public ConcreteFlyweight(String str){ string = str; } public void operation() { System.out.println("Concrete---Flyweight : " + string); } } package constructional.pattern.flyweight; import java.util.Hashtable; public class FlyweightFactory { private Hashtable flyweights = new Hashtable();// ----------------------------1 public FlyweightFactory() { } public Flyweight getFlyWeight(Object obj) { Flyweight flyweight = (Flyweight) flyweights.get(obj);// ----------------2 if (flyweight == null) {// ---------------------------------------------------3 // 产生新的ConcreteFlyweight flyweight = new ConcreteFlyweight((String) obj); flyweights.put(obj, flyweight);// --------------------------------------5 } return flyweight;// ---------------------------------------------------------6 } public int getFlyweightSize() { return flyweights.size(); } }

　　测试代码

package constructional.pattern.flyweight; public class FlyweightPattern { FlyweightFactory factory = new FlyweightFactory(); Flyweight fly1; Flyweight fly2; Flyweight fly3; Flyweight fly4; Flyweight fly5; Flyweight fly6; /** */ /** Creates a new instance of FlyweightPattern */ public FlyweightPattern() { fly1 = factory.getFlyWeight("Google"); fly2 = factory.getFlyWeight("Qutr"); fly3 = factory.getFlyWeight("Google"); fly4 = factory.getFlyWeight("Google"); fly5 = factory.getFlyWeight("Google"); fly6 = factory.getFlyWeight("Google"); } public void showFlyweight() { fly1.operation(); fly2.operation(); fly3.operation(); fly4.operation(); fly5.operation(); fly6.operation(); int objSize = factory.getFlyweightSize(); System.out.println("objSize = " + objSize); } public static void main(String[] args) { System.out.println("The FlyWeight Pattern!"); FlyweightPattern fp = new FlyweightPattern(); fp.showFlyweight(); } }

　　运行结果

转载于:https://www.cnblogs.com/liunianfeiyu/p/10116607.html