package com.peidasoft.dateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class DateUtil {public static  String formatDate(Date date)throws ParseException{SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");return sdf.format(date);}public static Date parse(String strDate) throws ParseException{SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");return sdf.parse(strDate);}
}

package com.peidasoft.dateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class DateUtil {private static final  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");public static  String formatDate(Date date)throws ParseException{return sdf.format(date);}public static Date parse(String strDate) throws ParseException{return sdf.parse(strDate);}
}

package com.peidasoft.dateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class DateUtil {private static final  SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");public static  String formatDate(Date date)throws ParseException{return sdf.format(date);}public static Date parse(String strDate) throws ParseException{return sdf.parse(strDate);}
}

package com.peidasoft.dateformat;import java.text.ParseException;
import java.util.Date;public class DateUtilTest {public static class TestSimpleDateFormatThreadSafe extends Thread {@Overridepublic void run() {while(true) {try {this.join(2000);} catch (InterruptedException e1) {e1.printStackTrace();}try {System.out.println(this.getName()+":"+DateUtil.parse("2013-05-24 06:02:20"));} catch (ParseException e) {e.printStackTrace();}}}    }public static void main(String[] args) {for(int i = 0; i < 3; i++){new TestSimpleDateFormatThreadSafe().start();}}
}

Exception in thread "Thread-1" java.lang.NumberFormatException: multiple pointsat sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1082)at java.lang.Double.parseDouble(Double.java:510)at java.text.DigitList.getDouble(DigitList.java:151)at java.text.DecimalFormat.parse(DecimalFormat.java:1302)at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1589)at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)at java.text.DateFormat.parse(DateFormat.java:335)at com.peidasoft.orm.dateformat.DateNoStaticUtil.parse(DateNoStaticUtil.java:17)at com.peidasoft.orm.dateformat.DateUtilTest$TestSimpleDateFormatThreadSafe.run(DateUtilTest.java:20)
Exception in thread "Thread-0" java.lang.NumberFormatException: multiple pointsat sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1082)at java.lang.Double.parseDouble(Double.java:510)at java.text.DigitList.getDouble(DigitList.java:151)at java.text.DecimalFormat.parse(DecimalFormat.java:1302)at java.text.SimpleDateFormat.subParse(SimpleDateFormat.java:1589)at java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1311)at java.text.DateFormat.parse(DateFormat.java:335)at com.peidasoft.orm.dateformat.DateNoStaticUtil.parse(DateNoStaticUtil.java:17)at com.peidasoft.orm.dateformat.DateUtilTest$TestSimpleDateFormatThreadSafe.run(DateUtilTest.java:20)
Thread-2:Mon May 24 06:02:20 CST 2021
Thread-2:Fri May 24 06:02:20 CST 2013
Thread-2:Fri May 24 06:02:20 CST 2013
Thread-2:Fri May 24 06:02:20 CST 2013

 private StringBuffer format(Date date, StringBuffer toAppendTo,FieldDelegate delegate) {// Convert input date to time field list
        calendar.setTime(date);boolean useDateFormatSymbols = useDateFormatSymbols();for (int i = 0; i < compiledPattern.length; ) {int tag = compiledPattern[i] >>> 8;int count = compiledPattern[i++] & 0xff;if (count == 255) {count = compiledPattern[i++] << 16;count |= compiledPattern[i++];}switch (tag) {case TAG_QUOTE_ASCII_CHAR:toAppendTo.append((char)count);break;case TAG_QUOTE_CHARS:toAppendTo.append(compiledPattern, i, count);i += count;break;default:subFormat(tag, count, delegate, toAppendTo, useDateFormatSymbols);break;}}return toAppendTo;}

package com.peidasoft.dateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class DateUtil {public static  String formatDate(Date date)throws ParseException{SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");return sdf.format(date);}public static Date parse(String strDate) throws ParseException{SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");return sdf.parse(strDate);}
}

package com.peidasoft.dateformat;import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class DateSyncUtil {private static SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");public static String formatDate(Date date)throws ParseException{synchronized(sdf){return sdf.format(date);}  }public static Date parse(String strDate) throws ParseException{synchronized(sdf){return sdf.parse(strDate);}} 
}

package com.peidasoft.dateformat;import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class ConcurrentDateUtil {private static ThreadLocal<DateFormat> threadLocal = new ThreadLocal<DateFormat>() {@Overrideprotected DateFormat initialValue() {return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");}};public static Date parse(String dateStr) throws ParseException {return threadLocal.get().parse(dateStr);}public static String format(Date date) {return threadLocal.get().format(date);}
}

package com.peidasoft.dateformat;import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;public class ThreadLocalDateUtil {private static final String date_format = "yyyy-MM-dd HH:mm:ss";private static ThreadLocal<DateFormat> threadLocal = new ThreadLocal<DateFormat>(); public static DateFormat getDateFormat()   {  DateFormat df = threadLocal.get();  if(df==null){  df = new SimpleDateFormat(date_format);  threadLocal.set(df);  }  return df;  }  public static String formatDate(Date date) throws ParseException {return getDateFormat().format(date);}public static Date parse(String strDate) throws ParseException {return getDateFormat().parse(strDate);}   
}