package com.tanlu.user.util;

 import java.text.DateFormat;

 import java.text.ParseException;

 import java.text.SimpleDateFormat;

 import java.util.Date;

 /**

  * 考虑到SimpleDateFormat为线程不安全对象，故应用ThreadLocal来解决，

  * 使SimpleDateFormat从独享变量变成单个线程变量

  */

 public class ThreadLocalDateUtil {

     //写法1：

     /*private static ThreadLocal<DateFormat> threadLocal = new ThreadLocal<DateFormat>() {

         @Override

         protected 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);

     }*/

     //写法2：

     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);

     }

 }