概念
单例模式(Singleton Pattern)目的是保证虚拟机中只有一个实例。
Java实现
饿汉模式
懒汉模式
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| public class Singleton {
private final static Singleton singleton = new Singleton();
private Singleton() {
}
public static Singleton getInstance() {
return singleton;
}
}
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懒汉模式
方法锁模式
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| public class Singleton {
private static Singleton singleton;
private Singleton() {
}
public static synchronized Singleton getInstance() {
if (singleton == null) {
singleton = new Singleton();
}
return singleton;
}
}
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双重锁模式
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| public class Singleton {
private volatile static Singleton singleton;
private Singleton() {
}
public static Singleton getInstance() {
if (singleton == null) {
synchronized (Singleton.class) {
if (singleton == null) {
singleton = new Singleton();
}
}
}
return singleton;
}
}
|
