享元模式

享元模式是对象的结构模式。享元模式以共享的方式高效地支持大量的细粒度对象。
 1 import java.util.HashMap;
 2 import java.util.Map;
 3 
 4 //抽象享元接口
 5 interface Flyweight{
 6     //state参数为外蕴状态
 7     public void method(String state);
 8 }
 9 
10 //具体享元类
11 class ConcreteFlyweight implements Flyweight{
12 
13     private String inState;
14     
15     //内蕴状态作为参数传入
16     public ConcreteFlyweight(String inState){
17         this.inState = inState;
18     }
19     
20     @Override
21     public void method(String state) {
22         System.out.println("外蕴状态" + state);
23         System.out.println("内蕴状态" + inState);
24     }
25     
26 }
27 
28 //享元工厂类
29 class FlyweightFactory{
30     
31     private Map<String, Flyweight> flies = new HashMap<String, Flyweight>();
32     
33     public Flyweight factory(String inState){
34         //从缓存中查询有没有指定的变量
35         Flyweight fly = flies.get(inState);
36         if(null == fly){
37             fly = new ConcreteFlyweight(inState);
38             flies.put(inState, fly);
39         }
40         return fly;
41     }
42 }