java线程学习之Sleep方法

sleep方法是在线程中常用到的一个方法,它是一个静态方法。

sleep(long millis)       在指定的毫秒数内让当前正在执行的线程休眠（暂停执行），此操作受到系统计时器和调度程序精度和准确性的影响。它可能会抛出中断异常

InterruptedException。它在Thread中定义的为：

    /**
     * Causes the currently executing thread to sleep (temporarily cease
     * execution) for the specified number of milliseconds, subject to
     * the precision and accuracy of system timers and schedulers. The thread
     * does not lose ownership of any monitors.
     *
     * @param  millis
     *         the length of time to sleep in milliseconds
     *
     * @throws  IllegalArgumentException
     *          if the value of {@code millis} is negative
     *
     * @throws  InterruptedException
     *          if any thread has interrupted the current thread. The
     *          <i>interrupted status</i> of the current thread is
     *          cleared when this exception is thrown.
     */
    public static native void sleep(long millis) throws InterruptedException;

sleep(long millis, int nanos)
          在指定的毫秒数加指定的纳秒数内让当前正在执行的线程休眠（暂停执行），此操作受到系统计时器和调度程序精度和准确性的影响。

在jdk的Thread中定义如下

  /**
      * Causes the currently executing thread to sleep (temporarily cease
      * execution) for the specified number of milliseconds plus the specified
      * number of nanoseconds, subject to the precision and accuracy of system
      * timers and schedulers. The thread does not lose ownership of any
      * monitors.
      *
      * @param  millis
      *         the length of time to sleep in milliseconds
      *
      * @param  nanos
      *         {@code 0-999999} additional nanoseconds to sleep
      *
      * @throws  IllegalArgumentException
      *          if the value of {@code millis} is negative, or the value of
      *          {@code nanos} is not in the range {@code 0-999999}
      *
      * @throws  InterruptedException
      *          if any thread has interrupted the current thread. The
      *          <i>interrupted status</i> of the current thread is
      *          cleared when this exception is thrown.
      */
     public static void sleep(long millis, int nanos)
     throws InterruptedException {
         if (millis < 0) {
             throw new IllegalArgumentException("timeout value is negative");
         }

         if (nanos < 0 || nanos > 999999) {
             throw new IllegalArgumentException(
                                 "nanosecond timeout value out of range");
         }

         if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
             millis++;
         }

         sleep(millis);
     }

例子一：

 package com.song.test;

 import java.util.Date;

 public class TestThread01 extends Thread {
     public static void main(String[] args) {
         TestThread01 test = new TestThread01();
         test.start();
     }

     @Override
     public void run() {
         long time1 = System.currentTimeMillis();

         System.out.println("现在时间" + time1);
         try {
             sleep(2000);
             long time2= System.currentTimeMillis();
             System.out.println("休眠2秒后" + time2);
             System.out.println(time2-time1);
             sleep(1000,500000);
             long time3 = System.currentTimeMillis();
             System.out.println("休眠1000.5后：" + time3);
             System.out.println(time3-time2);//因为时间精度为毫秒，会造成误差
         } catch (InterruptedException e) {
             e.printStackTrace();
         } finally {

         }

     }
 }

运行结果为：