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- java关于日期的运算等处理方法
java关于日期的运算等处理方法 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;int thisMonth = myDate.getMonth() + 1; int thisDate = myDate.getDate();%>
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());%> 输出格式为： 0000-00-00
4、获取数据库中字段名为”publish_time“、类型为Datetime的值 <%@ page import="java.util.Date"%><%ResultSet rs = Date sDate = rs.getDate("publish_time");%>
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));%> 输出的结果为： It is 星期五 0000.00.00 at 00:00:00 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 = "2006-12-13"; 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 X 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.
<!-- 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"); } }
