java DateUtil工具类时间戳类型转换详解

package com.sinosoft.media.sms.util; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; public class DateUtil {    //当前时间  //public static Date DATE_NOW=new Date();        public static String getFullTimeStamp(){  return new SimpleDateFormat("yyyyMMddHHmmssSSS").format(new Date()) ;  }      public static String getSimpleTimeStamp(){  return new SimpleDateFormat("yyyyMMdd").format(new Date()) ;  }      public static String getTimeStampByPattern(String pattern){  return new SimpleDateFormat(pattern).format(new Date()) ;  }      public static String getTodayStr(){  return new SimpleDateFormat("yyyy-MM-dd").format(new Date()) ;  }      public static String getDateTimeStamp(Date date){  return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(date) ;  }    public static Date getDateByString(String str){  SimpleDateFormat sim=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");  Date dateTime = null;  try {   dateTime = sim.parse(str);  } catch (ParseException e) {   e.printStackTrace();  }  return dateTime;  }   }