Java设计模式之享元模式实例详解

package Flyweight;
public abstract class Flyweight{
public abstract void operation();
}

package 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 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();
}
}

package Flyweight;
import java.util.Hashtable;
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();
}
}

String a = "hello";
String b = "hello";
if(a == b)
System.out.println("OK");
else
System.out.println("Error");