偶遇java时间解析异常

先贴两个异常，不知大家见过没

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Exception in thread "pool-1-thread-42" java.lang.NumberFormatException: multiple pointsat sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1084)at java.lang.Double.parseDouble(Double.java:510)at java.text.DigitList.getDouble(DigitList.java:151)at java.text.DecimalFormat.parse(DecimalFormat.java:1303)at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1591)at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1312)at java.text.DateFormat.parse(DateFormat.java:335)at infoair.obcs.utilities.DateTimeUtils.validateDateTime(DateTimeUtils.java:294)at infoair.obcs.utilities.TestThread.run(DateTimeUtils.java:318)at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)at java.lang.Thread.run(Thread.java:619)

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Exception in thread "pool-1-thread-9" java.lang.NumberFormatException: For input string: ""at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)at java.lang.Long.parseLong(Long.java:431)at java.lang.Long.parseLong(Long.java:468)at java.text.DigitList.getLong(DigitList.java:177)at java.text.DecimalFormat.parse(DecimalFormat.java:1298)at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1591)at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1312)at java.text.DateFormat.parse(DateFormat.java:335)at infoair.obcs.utilities.DateTimeUtils.validateDateTime(DateTimeUtils.java:294)at infoair.obcs.utilities.TestThread.run(DateTimeUtils.java:318)at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)at java.lang.Thread.run(Thread.java:619)

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最近测试一个服务端连多个客户端时，服务端老是报这样的错误，自己debug又没有事情，于是自己写了个demo

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class TestThread extends Thread{String str = "1251-12-12 03:22:22";public void run(){while(true){ Date date = Test.validateDateTime(str); System.out.println(date); try {Thread.sleep(10);} catch (InterruptedException e) {e.printStackTrace();break; }}}}class Test{       public final static SimpleDateFormat dateTimeFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        /** *  * @param dateStr *            String 格式为"yyyy-MM-dd HH:mm:ss" * @return 日期 */public  static Date validateDateTime(String dateStr) {try {return dateStr == null || dateStr.equals("") ? null: dateTimeFormat.parse(dateStr);} catch (ParseException e) {//e.printStackTrace();return null;}}public static void main(String[] args) throws InterruptedException {ExecutorService exe = Executors.newCachedThreadPool();for (int i = 0; i < 100;i ++){exe.execute(new TestThread());}Thread.sleep(5000);exe.shutdownNow();}}

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测试上面的demo 就发现在多线程下九抛出了上面连个异常，查了下API，上面写着：

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类 SimpleDateFormat

<!-- Generated by javadoc (build 1.6.0-beta2) on Fri Mar 09 12:51:19 CST 2007 -->

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同步

日期格式是不同步的。建议为每个线程创建独立的格式实例。如果多个线程同时访问一个格式，则它必须是外部同步的。

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谨记，谨记。。。

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有兴趣的 ，来解释下那个异常是怎么发生的吧

1 楼 rocketball 2011-01-20 http://www.iteye.com/topic/882541
刚讨论过的话题 2 楼 mercyblitz 2011-01-20 线程安全问题啊，SimpleDateFormat要使用原型对象。