1、获取服务器端当前日期：
<%@ page import="java.util.date"%>
<%
date mydate = new date();
%>
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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
%>
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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());
%>
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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");
%>
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5、按照指定格式打印日期
<%@ 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));
%>
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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);
}
%>
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输出结果为：
fri nov 11 00:00:00 cst 1222
7、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()));
%>
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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
8、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);
%>
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输出结果为：
sat jan 01 00:00:00 cst 2000 is after fri dec 31 00:00:00 cst 1999
9、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++)
t1 = system.currenttimemillis();
out.println("<br>");
out.println("cyc ends at " + t1);
out.println("<br>");
out.println("this run took " + (t1-t0) + "ms.");
%>
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输出结果为：
cyc starts at 1054275312432
cyc ends at 1054275312442
this run took 10ms.
10：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);
%>
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输出结果为：
33,665,448,856.66
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