https://blog.guwendaquan.com/ 2026-04-30T18:49:16+00:00 https://blog.guwendaquan.com/ https://blog.guwendaquan.com/ttps://blog.guwendaquan.com/lib/tpl/twentyfifteen/images/favicon.ico text/html 2022-09-13T23:16:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://blog.guwendaquan.com/notes/tech_log/java/knowledge/base_concurrent/singleton_dcl?rev=1663082191&do=diff 单例模式和双重检查模式(DCL) 双重检查模式实现单例模式，使用volatile，代码如下： public class Singleton { private static volatile Singleton instance; private Singleton() { } public static Singleton getInstance() { if (instance == null) { synchronized (Singleton.class) { if (instance == null) { instance = new Singleton(); } } } return instance; } } text/html 2022-09-13T23:16:59+00:00 Anonymous (anonymous@undisclosed.example.com) https://blog.guwendaquan.com/notes/tech_log/java/knowledge/base_concurrent/synchronized?rev=1663082219&do=diff Java锁Synchronized对象锁和类锁区别 java的内置锁 每个java对象都可以用做一个实现同步的锁，这些锁成为内置锁。线程进入同步代码块或方法的时候会自动获得该锁，在退出同步代码块或方法时会释放该锁。获得内置锁的唯一途径就是进入这个锁的保护的同步代码块或方法。 text/html 2022-09-13T23:17:32+00:00 Anonymous (anonymous@undisclosed.example.com) https://blog.guwendaquan.com/notes/tech_log/java/knowledge/base_concurrent/volatile?rev=1663082252&do=diff 深入分析volatile的实现原理 通过前面一章我们了解了synchronized是一个重量级的锁，虽然JVM对它做了很多优化，而下面介绍的volatile则是轻量级的synchronized。如果一个变量使用volatile，则它比使用synchronized的成本更加低，因为它不会引起线程上下文的切换和调度。Java语言规范对volatile的定义如下：