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jsp中的日期问题及其它:d :d :d
/**
* @author imagebear
*/
日期问题
1、获取服务器端当前日期：
<%@ page import="java.util.date"%><% date mydate = new date();%>
2、获取当前年、月、日：
<%@ page import="java.util.date"%><% date mydate = new date(); int thisyear = mydate.getyear() + 1900;//thisyear = 2003 int thismonth = mydate.getmonth() + 1;//thismonth = 5 int thisdate = mydate.getdate();//thisdate = 30%>
3、按本地时区输出当前日期
<%@ page import="java.util.date"%><% date mydate = new date(); out.println(mydate.tolocalestring());%>
输出结果为：
2003-5-30
4、获取数据库中字段名为”publish_time“、类型为datetime的值
<%@ page import="java.util.date"%><% …连接数据库… resultset rs = … date sdate = rs.getdate("publish_time");%>[code]5、按照指定格式打印日期[code]<%@ page import="java.util.date"%><%@ page import="java.text.dateformat"%><% date dnow = new date(); simpledateformat formatter = new simpledateformat("e yyyy.mm.dd at hh:mm:ss a zzz"); out.println("it is " + formatter.format(dnow));%>
输出的结果为：
it is 星期五 2003.05.30 at 11:30:46 上午 cst
(更为详尽的格式符号请参看simpledateformat类)
6、将字符串转换为日期
<%@ page import="java.util.date"%><%@ page import="java.text.dateformat"%><% string input = "1222-11-11"; simpledateformat formatter = new simpledateformat("yyyy-mm-dd"); date t = null; try{ t = formatter.parse(input); out.println(t); }catch(parseexception e){ out.println("unparseable using " + formatter); }%>
输出结果为：
fri nov 11 00:00:00 cst 1222
7、计算日期之间的间隔
<%@ page import="java.util.date"%><%@ page import="java.text.dateformat"%><% string input = "2003-05-01"; simpledateformat formatter = new simpledateformat("yyyy-mm-dd"); date d1 = null; try{ d1 = formatter.parse(input); }catch(parseexception e){ out.println("unparseable using " + formatter); } date d2 = new date(); long diff = d2.gettime() – d1.gettime(); out.println("difference is " + (diff/(1000*60*60*24)) + " days.");%>
输出结果为：
difference is 29 days.
8、日期的加减运算
方法：用calendar类的add()方法
<%@ page import="java.util.*"%><%@ page import="java.text.*"%><% calendar now = calendar.getinstance(); simpledateformat formatter = new simpledateformat("e yyyy.mm.dd at hh:mm:ss a zzz"); out.println("it is now " + formatter.format(now.gettime())); now.add(calendar.day_of_year,-(365*2)); out.println("<br>"); out.println("two years ago was " + formatter.format(now.gettime()));%>
输出结果为：
it is now 星期五 2003.05.30 at 01:45:32 下午 cst
two years ago was 星期三 2001.05.30 at 01:45:32 下午 cst
9、比较日期
方法：用equals()、before()、after()方法
<%@ page import="java.util.*"%><%@ page import="java.text.*"%><% dateformat df = new simpledateformat("yyy-mm-dd"); date d1 = df.parse("2000-01-01"); date d2 = df.parse("1999-12-31"); string relation = null; if(d1.equals(d2)) relation = "the same date as"; else if(d1.before(d2)) relation = "before"; else relation = "after"; out.println(d1 +" is " + relation + + d2);%>
输出结果为：
sat jan 01 00:00:00 cst 2000 is after fri dec 31 00:00:00 cst 1999
10、记录一件事所花费的时间
方法：调用两次system.gettimemillis()方法，求差值
<%@ page import="java.text.*"%><% long t0,t1; t0 = system.currenttimemillis(); out.println("cyc starts at " + t0); int k = 0; for(int i =0;i<100000;i++){ k += i; } t1 = system.currenttimemillis(); out.println("<br>"); out.println("cyc ends at " + t1); out.println("<br>"); out.println("this run took " + (t1-t0) + "ms.");%>
输出结果为：
cyc starts at 1054275312432
cyc ends at 1054275312442
this run took 10ms.
其它：如何格式化小数
<%@ page import="java.text.*"%><% decimalformat df = new decimalformat(",###.00"); double anumber = 33665448856.6568975; string result = df.format(anumber); out.println(result);%>
输出结果为：
33,665,448,856.66
在网上经常看到有人问如何将 获得当前时间并转换成
yyyy-mm-dd 年-月-日
hh:mm:ss 小时-分钟-秒
yyyy-mm-dd hh:mm:ss 年-月-日 小时-分钟-秒
三种格式 下面就是 jsp gui 的使用方法
<!–
jsp获得当前日期
–>
<!– 导入处理时间类,此类内部都是静态方法,直接调用即可. –>
<%@ page import="com.mamak.util.timestring" %>
<%
//获得当前日期时间
string nowdate = timestring.getnowtime("yyyy-mm-dd");
string nowtime = timestring.getnowtime("hh:mm:ss");
string nowdatetime = timestring.getnowtime("yyyy-mm-dd hh:mm:ss");
out.println("nowdate: "+nowdate);
out.println("nowtime: "+nowtime);
out.println("nowdatetime: "+nowdatetime);
%>
//******************************************************
//gui 或java 小程序获得得当前日期
public class test()
{
public static void main(string abc[])
{
//直接包名点类名点方法名使用
system.out.println("nowdate: "+com.mamak.util.timestring.getnowtime("yyyy-mm-dd"));
system.out.println("nowtime: "+com.mamak.util.timestring.getnowtime("hh:mm:ss"));
system.out.println("nowdatetime: "+com.mamak.util.timestring.getnowtime("yyyy-mm-dd hh:mm:ss"));
}
}
//******************************************************
//获得时间的bean 文件名 timestring.java
package com.mamak.util;
import java.text.simpledateformat;
import java.util.calendar;
public class timestring
{
public timestring()
{
}
public static string getnowtime(string timeformat)
{
simpledateformat lformat = new simpledateformat(timeformat);
calendar now = calendar.getinstance();
string nowstr = lformat.format(now.gettime());
return nowstr;
}
public static string getnottime()
{
return getnowtime("yyyy-mm-dd");
}
}
