Java线程同步 获取系统时间_JAVA_编程开发_程序员俱乐部

需求：Web系统中有多处地方会将当前系统中的信息采用多种方式保存到同一文件夹中，
当多人同时要保存同一份信息的场合，经常会出现文件名重复。导致一系列问题。文件名称的区分是以    某些前缀 + yyyy-MM-dd HH:mm:ss  组成的。所以区分的关键就锁定到日期部分。使日期部分不重复。

import java.util.Calendar;

import org.apache.commons.lang3.time.DateFormatUtils;

public class CalendarUtils {
	
	public String getCurrendTime() {
		synchronized (CalendarUtils.class) {
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			
			Calendar calendar = Calendar.getInstance();
			
			return DateFormatUtils.format(calendar, "yyyy-MM-dd HH:mm:ss");		
		}
	}
}

首先使用synchronized关键字保证线程同步，并且同步对象要为CalendarUtils。
第二使用线程睡眠，保证每条线程访问的间隔为1秒钟。
输出结果：

Thread4==2012-06-10 18:07:45
Thread3==2012-06-10 18:07:46
Thread6==2012-06-10 18:07:47
Thread2==2012-06-10 18:07:48
Thread5==2012-06-10 18:07:49
Thread1==2012-06-10 18:07:50
Thread5==2012-06-10 18:07:51
Thread2==2012-06-10 18:07:52
Thread6==2012-06-10 18:07:53
Thread3==2012-06-10 18:07:54
Thread4==2012-06-10 18:07:55
Thread3==2012-06-10 18:07:56
Thread6==2012-06-10 18:07:57
Thread2==2012-06-10 18:07:58
Thread5==2012-06-10 18:07:59
Thread1==2012-06-10 18:08:00
Thread5==2012-06-10 18:08:01
Thread2==2012-06-10 18:08:02
Thread6==2012-06-10 18:08:03
Thread3==2012-06-10 18:08:04
Thread4==2012-06-10 18:08:05
Thread3==2012-06-10 18:08:06
Thread6==2012-06-10 18:08:07
Thread2==2012-06-10 18:08:08
Thread5==2012-06-10 18:08:09
Thread1==2012-06-10 18:08:10
Thread5==2012-06-10 18:08:11
Thread2==2012-06-10 18:08:12
Thread6==2012-06-10 18:08:13
Thread3==2012-06-10 18:08:14
Thread4==2012-06-10 18:08:15
Thread3==2012-06-10 18:08:16
Thread6==2012-06-10 18:08:17
Thread2==2012-06-10 18:08:18
Thread5==2012-06-10 18:08:19
Thread1==2012-06-10 18:08:20
Thread5==2012-06-10 18:08:21
Thread2==2012-06-10 18:08:22
Thread6==2012-06-10 18:08:23
Thread3==2012-06-10 18:08:24
Thread4==2012-06-10 18:08:25
Thread3==2012-06-10 18:08:26
Thread6==2012-06-10 18:08:27
Thread2==2012-06-10 18:08:28
Thread5==2012-06-10 18:08:29
Thread1==2012-06-10 18:08:30
Thread5==2012-06-10 18:08:31
Thread2==2012-06-10 18:08:32
Thread6==2012-06-10 18:08:33
Thread3==2012-06-10 18:08:34
Thread4==2012-06-10 18:08:35
Thread3==2012-06-10 18:08:36
Thread6==2012-06-10 18:08:37
Thread2==2012-06-10 18:08:38
Thread5==2012-06-10 18:08:39
Thread1==2012-06-10 18:08:40
Thread5==2012-06-10 18:08:41
Thread2==2012-06-10 18:08:42
Thread6==2012-06-10 18:08:43
Thread3==2012-06-10 18:08:44
Thread4==2012-06-10 18:08:45
Thread3==2012-06-10 18:08:46
Thread6==2012-06-10 18:08:47
Thread2==2012-06-10 18:08:48
Thread5==2012-06-10 18:08:49
Thread1==2012-06-10 18:08:50
Thread5==2012-06-10 18:08:51
Thread2==2012-06-10 18:08:52
Thread6==2012-06-10 18:08:53
Thread3==2012-06-10 18:08:54
Thread4==2012-06-10 18:08:55
Thread3==2012-06-10 18:08:56
Thread6==2012-06-10 18:08:57
Thread2==2012-06-10 18:08:58
Thread5==2012-06-10 18:08:59
Thread1==2012-06-10 18:09:00
Thread5==2012-06-10 18:09:01
Thread2==2012-06-10 18:09:02
Thread6==2012-06-10 18:09:03
Thread3==2012-06-10 18:09:04
Thread4==2012-06-10 18:09:05
Thread3==2012-06-10 18:09:06
Thread6==2012-06-10 18:09:07
Thread2==2012-06-10 18:09:08
Thread5==2012-06-10 18:09:09
Thread1==2012-06-10 18:09:10
Thread5==2012-06-10 18:09:11
Thread2==2012-06-10 18:09:12
Thread6==2012-06-10 18:09:13
Thread3==2012-06-10 18:09:14
Thread4==2012-06-10 18:09:15
Thread3==2012-06-10 18:09:16
Thread6==2012-06-10 18:09:17
Thread2==2012-06-10 18:09:18
Thread5==2012-06-10 18:09:19
Thread1==2012-06-10 18:09:20
Thread5==2012-06-10 18:09:21
Thread2==2012-06-10 18:09:22
Thread6==2012-06-10 18:09:23
Thread3==2012-06-10 18:09:24
Thread4==2012-06-10 18:09:25