java 常用Date操作
- 获取年月日时分秒:
- package com.util;
- import java.text.DateFormat;
- import java.util.Calendar;
- import java.util.Date;
- public class Test {
- public void getTimeByDate(){
- Date date = new Date();
- DateFormat df1 = DateFormat.getDateInstance();//日期格式,精确到日
- System.out.println(df1.format(date));
- DateFormat df2 = DateFormat.getDateTimeInstance();//可以精确到时分秒
- System.out.println(df2.format(date));
- DateFormat df3 = DateFormat.getTimeInstance();//只显示出时分秒
- System.out.println(df3.format(date));
- DateFormat df4 = DateFormat.getDateTimeInstance(DateFormat.FULL,DateFormat.FULL); //显示日期,周,上下午,时间(精确到秒)
- System.out.println(df4.format(date));
- DateFormat df5 = DateFormat.getDateTimeInstance(DateFormat.LONG,DateFormat.LONG); //显示日期,上下午,时间(精确到秒)
- System.out.println(df5.format(date));
- DateFormat df6 = DateFormat.getDateTimeInstance(DateFormat.SHORT,DateFormat.SHORT); //显示日期,上下午,时间(精确到分)
- System.out.println(df6.format(date));
- DateFormat df7 = DateFormat.getDateTimeInstance(DateFormat.MEDIUM,DateFormat.MEDIUM); //显示日期,时间(精确到分)
- System.out.println(df7.format(date));
- }
- public void getTimeByCalendar(){
- Calendar cal = Calendar.getInstance();
- int year = cal.get(Calendar.YEAR);//获取年份
- int month=cal.get(Calendar.MONTH);//获取月份
- int day=cal.get(Calendar.DATE);//获取日
- int hour=cal.get(Calendar.HOUR);//小时
- int minute=cal.get(Calendar.MINUTE);//分
- int second=cal.get(Calendar.SECOND);//秒
- int WeekOfYear = cal.get(Calendar.DAY_OF_WEEK);//一周的第几天
- System.out.println("现在的时间是:公元"+year+"年"+month+"月"+day+"日 "+hour+"时"+minute+"分"+second+"秒 星期"+WeekOfYear);
- }
- public static void main(String[] args) {
- Test t=new Test();
- t.getTimeByDate();
- System.out.println("****************************");
- t.getTimeByCalendar();
- }
- }
获取日,如果大于16则+2个月,否则+1个月,输出7个月
- public static void main(String[] as) throws Exception {
- int j;
- Calendar cc = Calendar.getInstance();
- int myYear = cc.get(Calendar.YEAR);
- int myMonth = cc.get(Calendar.MONTH);
- j=cc.get(Calendar.DATE)>16?3:2;
- cc.set(Calendar.MONTH, myMonth+j);
- System.out.println(myYear+"-"+cc.get(cc.MONTH));
- for(int i=0;i<7;i++){
- cc.add(cc.MONTH, 1);
- int mm = cc.get(cc.MONTH);
- int mmm=mm==0?12:mm;
- System.out.println(myYear+"-"+mmm);
- }
- }
这里有个博客http://www.blogjava.net/xiaoyi/articles/295044.html,里面有一些常用方法的实现,可以参考,自己在优化
Java中常用日期操作大全
1.计算某一月份的最大天数
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注:在使用set方法之前,必须先clear一下,否则很多信息会继承自系统当前时间
2.Calendar和Date的转化
(1) Calendar转化为Date
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(2) Date转化为Calendar
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3.格式化输出日期时间 (这个用的比较多)
其一
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4.计算一年中的第几星期
(1)计算某一天是一年中的第几星期
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(2)计算一年中的第几星期是几号
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输出:
2006-01-02
5.add()和roll()的用法(不太常用)
(1)add()方法
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输出:
2006-08-30
2006-09-03
(2)roll方法
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输出:
2006-09-29
2006-09-03
可见,roll()方法在本月内循环,一般使用add()方法;
6.计算两个任意时间中间的间隔天数(这个比较常用)
(1)传进Calendar对象
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(2)传进Date对象
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(3)改进精确计算相隔天数的方法
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注意:通过上面的方法可以衍生出求任何时间,如要查出邮箱三周之内收到的邮件(得到当前系统时间-再得到三周前时间)用收件的时间去匹配 最好装化成 long去比较
如:1年前日期(注意毫秒的转换)
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7. String 和 Date ,Long 之间相互转换 (最常用)
字符串转化成时间类型(字符串可以是任意类型,只要和SimpleDateFormat中的格式一致即可)
通常我们取时间跨度的时候,会substring出具体时间--long-比较
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8. 通过时间求时间
年月周求日期
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求是星期几
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9. java 和 具体的数据库结合
在开发web应用中,针对不同的数据库日期类型,我们需要在我们的程序中对日期类型做各种不同的转换。若对应数据库数据是Oracle的Date类型,即只需要年月日的,可以选择使用java.sql.Date类型,若对应的是MSsqlserver 数据库的DateTime类型,即需要年月日时分秒的,选择java.sql.Timestamp类型
你可以使用dateFormat定义时间日期的格式,转一个字符串即可
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原文链接:http://zcw-java.iteye.com/blog/1498125
http://www.blogjava.net/xiaoyi/articles/295044.html
- import java.util.regex.Matcher;
- import java.util.regex.Pattern;
- public class DateToUpperChinese {
- private static final String[] NUMBERS = { "零", "壹", "贰", "叁", "肆", "伍",
- "陆", "柒", "捌", "玖" };
- public static synchronized String toChinese(String str) {
- StringBuffer sb = new StringBuffer();
- sb.append(getSplitDateStr(str, 0)).append(" ").append(
- getSplitDateStr(str, 1)).append(" ").append(
- getSplitDateStr(str, 2));
- return sb.toString();
- }
- public static String getSplitDateStr(String str, int unit) {
- // unit是单位 0=年 1=月 2日
- String[] DateStr = str.split("-");
- if (unit > DateStr.length)
- unit = 0;
- StringBuffer sb = new StringBuffer();
- for (int i = 0; i < DateStr[unit].length(); i++) {
- if ((unit == 1 || unit == 2) && Integer.valueOf(DateStr[unit]) > 9) {
- sb.append(convertNum(DateStr[unit].substring(0, 1)))
- .append("拾").append(
- convertNum(DateStr[unit].substring(1, 2)));
- break;
- } else {
- sb.append(convertNum(DateStr[unit].substring(i, i + 1)));
- }
- }
- if (unit == 1 || unit == 2) {
- return sb.toString().replaceAll("^壹", "").replace("零", "");
- }
- return sb.toString();
- }
- private static String convertNum(String str) {
- return NUMBERS[Integer.valueOf(str)];
- }
- public static boolean isNumeric(String str) {
- Pattern pattern = Pattern.compile("[0-9]*");
- Matcher isNum = pattern.matcher(str);
- if (!isNum.matches()) {
- return false;
- }
- return true;
- }
- public static void main(String args[]) {
- System.out.println(toChinese("2008-10-02"));
- }
- }