java日期工具类

package util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import org.apache.log4j.Logger;

public class DateUtil {

private static final Logger logger = Logger.getLogger(DateUtil.class);
public static final String DIFF_H = "H";//相差多少小时
public static final String DIFF_M = "M";//相差多少分钟
public static final String TIMEFORMAT_12 = "12";
public static final String TIMEFORMAT_24 = "24";

public static void main(String[] args) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date begintime;
Date endtime;
try {
begintime = sdf.parse("2016-04-06 17:00:00");
endtime = sdf.parse("2016-04-06 17:03:00");
DateUtil.differenceTime(begintime, endtime,DateUtil.DIFF_H);
} catch (ParseException e) {
e.printStackTrace();
}
}

/****
* @param beginTime
* @param currentTime
* @param difftype
* @return
*/
public static Long differenceTime(Date beginTime, Date currentTime, String diffType) {

long begintime = beginTime.getTime();
long endtime = currentTime.getTime();
long diff;
long diffTime;
if (begintime < endtime) {
diff = endtime - begintime;
if(DateUtil.DIFF_H.equals(diffType)){
diffTime = diff / (60*60* 1000);
logger.info("相差"+diffTime+"小时");
}else if(DateUtil.DIFF_M.equals(diffType)){
diffTime = diff / (60* 1000);
logger.info("相差"+diffTime+"分钟");
}
} else {
logger.error("开始日期必须小于结束日期");
}
return null;
}

/****
* 2008-05-28 01:32:54
* 2008-05-28 13:32:54
* @param time 时间
* @param Timeformat 时间格式(12/24)
* @return
*/
public static String formatTime(String time,String Timeformat) {

Date d = new Date();
SimpleDateFormat ss = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");// 12小时制
System.out.println(ss.format(d));
Date date = new Date();
SimpleDateFormat sdformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");// 24小时制
String LgTime = sdformat.format(date);
System.out.println(LgTime);

return LgTime;
}

public void test1() throws ParseException{
SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMdd");
String str="20110823";
Date dt=sdf.parse(str);
Calendar rightNow = Calendar.getInstance();
rightNow.setTime(dt);
rightNow.add(Calendar.YEAR,-1);//日期减1年
rightNow.add(Calendar.MONTH,3);//日期加3个月
rightNow.add(Calendar.DAY_OF_YEAR,10);//日期加10天
}

}