Singleton Pattern
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1、单例模式：也叫单件模式，或单态模式。表示创建独一无二的(只有一个实例的)对象。
2、经典单例模式：延迟实例化(适用于非多线程)
/** * @Class:classical signleton instance example:lazy instantiaze * @Author:bufubuxing * @Email:softwaredesigner@hotmail.com * @Date:2008/03/22 */ public class SingletonInstance{ //define a unique instance of this class by a static variable private static Singleton uniqueInstance; //private construct function private SingletonInstance(){} //getInstance: exist ? this : new public static SingletonInstance getInstance(){ //lazy instantiaze if(uniqueInstance == null){ uniqueInstance = new SingletonInstance(); } return uniqueInstance; } //TODO: Other somethings } 3、处理多线程单例模式：急切实例化(适用于多线程：编程简单，但过早实例化，增加负担)
/**
* @Class: multithreading Singleton Pattern Instance example:eagerly instantiaze * @Author:bufubuxing * @Email:softwaredesigner@hotmail.com * @Date:2008/03/22 */ public class SingletonInstance{ //eagerly instantiaze when JVM loading it private static Singleton uniqueInstance = new SingletonInstance(); //private construct function private SingletonInstance(){} //getInstance public static SingletonInstance getInstance(){ return uniqueInstance; } //TODO:Other somethings } 4、处理多线程单例模式：同步getInstance()(适用于多线程：编程简单，但效率相当低)
/** * @Class: multithreading Singleton Pattern instance example:synchronized getInstance() * @Author:bufubuxing * @Email:softwaredesigner@hotmail.com * @Date: 2008/03/22 */ public class SingletonInstance{ //define a static variable of this class private static SingletonInstance uniqueInstance; //private construct function private SingletonInstance(){} //getInstance():synchronized public static synchronized SingletonInstance getInstance(){ //lazy instantiaze if(uniqueInstance == null){ uniqueInstance = new SingletonInstance(); } return uniqueInstance; } //TODO:Other somethings } 5、处理多线程单例模式：双重检查锁(适用于多线程：效率较高，但JDK1.5以上支持)
/** * @Class: multithreading Singleton Pattern instance example:double-checked locking * @Author:bufubuxing * @Email:softwaredesigner@hotmail.com * @Date: 2008/03/22 */ public class SingletonInstance{ //volatile-lock checked:define a static variable of this class private volatile static SingletonInstance uniqueInstance; //private construct function private SingletonInstance(){} //getInstance():synchronized-lock checked public static SingletonInstance getInstance(){ //lazy instantiaze if(uniqueInstance == null){ synchronized(SingletonInstance.class){ if(uniqueInstance == null){ uniqueInstance = new SingletonInstance(); } } } return uniqueInstance; } //TODO:Other somethings } 本文出自 “不服不行” 博客，转载请与作者联系！ 本文出自 51CTO.COM技术博客 |
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