展示开始时间与结束时间之间每个年月

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;import junit.framework.TestCase;
 
public class Test extends TestCase {
 public  String formatDate(java.util.Date _date, String _pattern) {
  if( _date == null) {
   return null;
  }
  SimpleDateFormat simpleDateFormat = new SimpleDateFormat(_pattern);
  String stringDate = simpleDateFormat.format(_date);
  return stringDate;
 }
 public  java.util.Date changeToDate(String _dateStr,String _pattern)  {
  if (_dateStr == null || _dateStr.trim().equals("")) {
   return null;
  }
  java.util.Date date = null;
  SimpleDateFormat format = new SimpleDateFormat(_pattern);
  try {
   date = format.parse(_dateStr);
  } catch (java.text.ParseException pe) {  }
  return date;
 }
 private String formatContractMonth(String begin_time,String end_time) throws Exception{
  Date begin_date = changeToDate(begin_time,"yyyy-MM-dd");
  Date end_date = changeToDate(end_time,"yyyy-MM-dd");
  if( begin_date.compareTo(end_date)>0) {
   return "";
  }
  GregorianCalendar g_begin_date = new GregorianCalendar();  
  GregorianCalendar g_end_date = new GregorianCalendar();   
  g_begin_date.setTime(begin_date);
  g_end_date.setTime(end_date);
  int x=0;  String str="";
  str+=formatDate(g_begin_date.getTime(), "yyyy-MM")+",";
  while((g_begin_date.get(g_begin_date.YEAR) != g_end_date.get(g_end_date.YEAR))||(g_begin_date.get(g_begin_date.MONTH) != g_end_date.get(g_end_date.MONTH))) {
   g_begin_date.add(g_begin_date.MONTH, 1);
   str+=formatDate(g_begin_date.getTime(), "yyyy-MM")+",";
  }
     if(str.length()>0) {
      str=str.substring(0,str.length()-1);
     }
  System.out.println(str);
      
  return str;
 }
 public static void main(String[] args) {
  Test t = new Test();
  try {
   t.formatContractMonth("2011-01-15", "2011-12-26");
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
}