设计模式之单例
2019-07-16 本文已影响0人
Richair_Ann
//饿汉式 不推荐
public class Singleton{
private static final Singleton singleton = new Singleton();
public static Singleton getInstance(){
return singleton;
}
}
//懒汉式 不推荐
public class Singleton{
private static Singleton singleton;
private Singleton(){
}
public static sysnchronized Singleton getInstance(){
if(null==instance){
instance = new Singleton();
}
return instance;
}
}
//双重检查锁定(DCL) 不推荐懒汉式的优化版
public class Singleton{
private static Singleton instance = null;
private Singleton(){
}
public static Singleton getInstance(){
if(null == instance){
synchronized(Singleton.class){
if(null==instace){
instance = new Singleton
}
}
}
return instance;
}
}
//静态内部单例 推荐
public class Singleton{
private static Singleton getInstance(){
return Singletons.singleton;
}
private static class Singletons{
private static final Singleton singleton = new Singleton();
}
}
//枚举单例 推荐
public enum Singleton{
INSTANCE;
public void doSomething(){
System.out.println("操作单例");
}
}
//使用容器
public class SingletonManager{
private static Map<String,Object> objMap = new HashMap<String,Object>();
public static void registerService(String key ,Object instance){
if(!objMap.containsKey(key)){
objMap.put(instance);
}
}
public static Object getService(String key){
return objMap.get(key);
}
}