一、静态变量初始化实现线程安全的单例模式
static
变量instance
是在类被加载时初始化并仅被初始化一次,这样就可以保证只有一个instance被初始化。
public class Singleton {
private static Singleton instance = new Singleton();
private Singleton(){}
public static Singleton getInstance(){
return instance;
}
}
二、经典的非线程安全单例模式实现类
public class Singleton {
private static Singleton instance;
private Singleton(){ }
public static Singleton getInstance(){
if(instance == null){
instance = new Singleton();
}
return instance;
}
}
三、线程安全的单例模式实现类
public class Singleton {
private static Singleton instance;
private Singleton(){}
public static synchronized Singleton getInstance(){
if(instance == null){
instance = new Singleton();
}
return instance;
}
}
四、高效的线程安全的单例模式实现类
public class Singleton {
private static volatile Singleton instance;
private Singleton(){}
public static Singleton getInstance(){
if(instance == null){
//类锁
synchronized(Singleton.class){
if(instance == null){
instance = new Singleton();
}
}
}
return instance;
}
}
写在最后:
以上是我工作中常遇到的单例模式实现方式,欢迎补充…