多线程的同步和异步讲解案例

package com.dj; public class SynTest { // 非同步 static void method(Thread thread) { System.out.println("begin0 " + thread.getName()); try { Thread.sleep(3000); } catch (Exception ex) { ex.printStackTrace(); } System.out.println("end " + thread.getName()); } //同步方式一：同步方法 这个方法是同步的方法，每次只有一个线程可以进来 synchronized static void method1(Thread thread) { System.out.println("begin1 " + thread.getName()); try { Thread.sleep(3000); } catch (Exception ex) { ex.printStackTrace(); } System.out.println("end " + thread.getName()); } //同步方式二：同步代码块 static void method2(Thread thread) { synchronized (SynTest.class) { System.out.println("begin2 " + thread.getName()); try { Thread.sleep(3000); } catch (Exception ex) { ex.printStackTrace(); } System.out.println("end " + thread.getName()); } } //同步方式三：使用同步对象锁 private static Object _lock1 = new Object(); private static byte _lock2[] = {};//据说，此锁更可提高性能。源于：锁的对象越小越好 static void method3(Thread thread) { synchronized (_lock1) { System.out.println("begin3 " + thread.getName()); try { Thread.sleep(3000); } catch (Exception ex) { ex.printStackTrace(); } System.out.println("end " + thread.getName()); } } public static void main(String[] args) { //启动3个线程，这里用了匿名类 for (int i = 0; i < 3; i++) { new Thread() { public void run() { // method(this); // method1(this); // method2(this); method3(this); } }.start(); } } }