享元模式(Flyweight Pattern)主要用于减少创建对象的数量，以减少内存占用和提高性能。这种类型的设计模式属于结构型模式，它提供了减少对象数量从而改善应用所需的对象结构的方式。
Diagram
Implementation
享元接口
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| public interface Flyweight {
void doOperation(String extrinsicState);
}
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享元实例
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| public class ConcreteFlyweight implements Flyweight{
private String intrinsicState;
public ConcreteFlyweight(String intrinsicState) {
this.intrinsicState = intrinsicState;
}
@Override
public void doOperation(String extrinsicState) {
System.out.println("Object address: " + System.identityHashCode(this));
System.out.println("IntrinsicState: " + intrinsicState);
System.out.println("ExtrinsicState: " + extrinsicState);
}
}
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享元工厂类
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| public class FlyweightFactory {
private HashMap<String,Flyweight> flyweightHashMap = new HashMap<>();
Flyweight getFlyweight(String intrinsicState){
if(!flyweightHashMap.containsKey(intrinsicState)){
Flyweight flyweight = new ConcreteFlyweight(intrinsicState);
flyweightHashMap.put(intrinsicState,flyweight);
}
return flyweightHashMap.get(intrinsicState);
}
}
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测试类
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| public class FlyweightTest {
@Test
public void test() {
FlyweightFactory factory = new FlyweightFactory();
Flyweight flyweight1 = factory.getFlyweight("aa");
Flyweight flyweight2 = factory.getFlyweight("aa");
flyweight1.doOperation("x");
flyweight2.doOperation("y");
}
}
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Example
Java 利用缓存来加速大量小对象的访问时间。
- java.lang.Integer#valueOf(int)
- java.lang.Boolean#valueOf(boolean)
- java.lang.Byte#valueOf(byte)
- java.lang.Character#valueOf(char)
Reflence