根据今天日期获取昨天日期

package test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
public class Test1
{
 public static void main(String[] args)
 {
  Test1 test1 = new Test1();
  //String today = GTime.getTime(GTime.YYYYMMDD);
  //System.out.println(test1.getYestoday(today));
  System.out.println(test1.getYestoday("20090122"));

 }
 public String getYestoday(String todayDataStr)
 {
   //根据今天日期获取昨天日期
   SimpleDateFormat DateFormat = new SimpleDateFormat("yyyyMMdd");
   GregorianCalendar cal = new GregorianCalendar();
   Date date;
   String yestodayDate = "";
   try
   {
    date = DateFormat.parse(todayDataStr);
    cal.setTime(date);
       cal.add(Calendar.DAY_OF_MONTH, -1);
       yestodayDate = DateFormat.format(cal.getTime());
   }
  catch (ParseException e)
  {
    e.getMessage();
  }
  return yestodayDate;
 }
}