java中时间比较

package com.newtouch.test;

import java.text.SimpleDateFormat;
import java.util.Date;

public class TimeCompare {
public static void main(String[] args) {
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
try {
Date d1 = df.parse("2004-03-26 13:31:40");
Date d2 = df.parse("2004-01-02 11:30:24");
long diff = d1.getTime() - d2.getTime();
long days = diff / (1000 * 60 * 60 * 24);
System.out.println(days);

// //////////////////////////////////////////////////////////

java.util.Date now = df.parse("2004-03-26 13:31:40");
java.util.Date date = df.parse("2004-01-02 11:30:24");
long l = now.getTime() - date.getTime();
long day = l / (24 * 60 * 60 * 1000);
long hour = (l / (60 * 60 * 1000) - day * 24);
long min = ((l / (60 * 1000)) - day * 24 * 60 - hour * 60);
long s = (l / 1000 - day * 24 * 60 * 60 - hour * 60 * 60 - min * 60);
System.out.println("" + day + "天" + hour + "小时" + min + "分" + s + "秒");

// //////////////////////////////////////////////////////////

SimpleDateFormat dfs = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
java.util.Date begin = dfs.parse("2004-01-02 11:30:24");
java.util.Date end = dfs.parse("2004-03-26 13:31:40");
long between = (end.getTime() - begin.getTime()) / 1000;// 除以1000是为了转换成秒
long day1 = between / (24 * 3600);
long hour1 = between % (24 * 3600) / 3600;
long minute1 = between % 3600 / 60;
long second1 = between % 60 / 60;
System.out.println("" + day1 + "天" + hour1 + "小时" + minute1 + "分" + second1 + "秒");

////////////////////////////////////////////////////////////

String s1="2008-01-25 09:12:09";
String s2="2008-01-29 09:12:11";
java.util.Calendar c1=java.util.Calendar.getInstance();
java.util.Calendar c2=java.util.Calendar.getInstance();
try {
c1.setTime(df.parse(s1));
c2.setTime(df.parse(s2));
}catch(java.text.ParseException e){
System.err.println("格式不正确");
}
int result=c1.compareTo(c2);
if(result==0)
System.out.println("c1相等c2");
else if(result<0)
System.out.println("c1小于c2");
else
System.out.println("c1大于c2");

} catch (Exception e) {

}
}
}