一、在多线程环境下创建单例
方式一：
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package com.ietree.multithread.sync;
public class Singletion {
private static class InnerSingletion {
private static Singletion single = new Singletion();
}
public static Singletion getInstance() {
return InnerSingletion.single;
}
}
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方式二：
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package com.ietree.multithread.sync;
public class DubbleSingleton {
private static DubbleSingleton ds;
public static DubbleSingleton getDs() {
if (ds == null) {
try {
// 模拟初始化对象的准备时间...
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (DubbleSingleton.class) {
if (ds == null) { // 这个判断很重要，如果没有那将不是单例，而是多例
ds = new DubbleSingleton();
}
}
}
return ds;
}
public static void main(String[] args) {
Thread t1 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println(DubbleSingleton.getDs().hashCode());
}
}, "t1");
Thread t2 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println(DubbleSingleton.getDs().hashCode());
}
}, "t2");
Thread t3 = new Thread(new Runnable() {
@Override
public void run() {
System.out.println(DubbleSingleton.getDs().hashCode());
}
}, "t3");
t1.start();
t2.start();
t3.start();
}
}
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原文链接：http://www.cnblogs.com/Dylansuns/p/6719764.html