java 比较时间

//获取日期差，返回相差天数。
public static long getCompareDate(String startDate,String endDate) throws ParseException {
    SimpleDateFormat formatter=new SimpleDateFormat("yyyy-MM-dd");
      Date date1=formatter.parse(startDate);
      Date date2=formatter.parse(endDate);
      long l = date2.getTime() - date1.getTime();
      long d = l/(24*60*60*1000);
    return d;
}

public static String getTimeStampNumberFormat(Timestamp formatTime) {
        SimpleDateFormat m_format = new SimpleDateFormat("yyyy-MM-dd,HH:mm:ss", new Locale("zh", "cn"));
        return m_format.format(formatTime);
    }

    public static String getTimeDifference(Timestamp formatTime1, Timestamp formatTime2) {
        SimpleDateFormat timeformat = new SimpleDateFormat("yyyy-MM-dd,HH:mm:ss");
        long t1 = 0L;
        long t2 = 0L;
        try {
            t1 = timeformat.parse(getTimeStampNumberFormat(formatTime1)).getTime();
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            t2 = timeformat.parse(getTimeStampNumberFormat(formatTime2)).getTime();
        } catch (ParseException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //因为t1-t2得到的是毫秒级,所以要初3600000得出小时.算天数或秒同理
        int hours=(int) ((t1 - t2)/3600000);
        int minutes=(int) (((t1 - t2)/1000-hours*3600)/60);
        return ""+hours+"小时"+minutes+"分";
    }

import java.text.SimpleDateFormat;
import java.util.Date;
public class Test {/**
* @param args
*/
public static void main(String[] args)
{
String datestr1 ="" ;
String datestr2 ="" ;
String datestr3 ="" ;
try {
java.text.DateFormat df1 = new java.text.SimpleDateFormat("yyyy-MM-dd") ;
java.text.DateFormat df2 = new java.text.SimpleDateFormat("yyyy年MM月dd日 HH点ss分") ;
Date tempDate=new java.util.Date();
datestr1 = df1.format(tempDate) ;//格式化日期
datestr2 = df2.format(tempDate) ;

SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
String ymd ="2006-08-07";
Date date1 = myFormatter.parse(ymd);
datestr3 = String.valueOf((tempDate.getTime()-date1.getTime())/(24*60*60*1000));//计算两个日期之间的时间差，本例为计算天数
}
catch (Exception ex) {}
System.out.println(datestr1);
System.out.println(datestr2);
System.out.println(datestr3);
}