日期工具类

package com.hnmmli.g2common.utils;

import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

import org.apache.commons.lang.UnhandledException;



/**
*
* @Company : hiaas.com
* @comment
* 说明：日期时间相关的一些方法
* @author yuzhizhong
* @create  2014年4月19日 上午9:24:22
*/
public class DateHelper {

public static final long SECOND = 1000;
public static final long MINITE = SECOND * 60;
public static final long HOUR = MINITE * 60;
public static final long DAY = HOUR * 24;

public static final String TIME_MIN = "00:00:00";

public static final String TIME_MAX = "23:59:59";

public static final String HOUR_MINITE = "HH:mm";

public static final SimpleDateFormat dateSdf = new SimpleDateFormat("yyyyMMdd");

public static final SimpleDateFormat timeSdf = new SimpleDateFormat("HHmmss");

public static final SimpleDateFormat timeSdf2 = new SimpleDateFormat("HHmm");

/**
* 说明：将DateTime中的Date转换成Integer
* @param date
* @return
*/
public static final int getDateInt(Date date){
return Integer.valueOf(dateSdf.format(date));
}

/**
* 说明：将DateTime中的Time转换成Integer
* @param date
* @return
*/
public static final int getTimeInt(Date date){
return Integer.valueOf(timeSdf.format(date));
}


/**
* 说明：将DateTime中的Time转换成Integer
* @param date
* @return
*/
public static final int getTime2Int(Date date){
return Integer.valueOf(timeSdf2.format(date));
}


// order is like this because the SimpleDateFormat.parse does not fail with
// exception
// if it can parse a valid date out of a substring of the full string given
// the mask
// so we have to check the most complete format first, then it fails with
// exception
private static final String[] RFC822_MASKS = {
"EEE, dd MMM yy HH:mm:ss z",
"EEE, dd MMM yy HH:mm z",
"dd MMM yy HH:mm:ss z",
"dd MMM yy HH:mm z"
};

// order is like this because the SimpleDateFormat.parse does not fail with
// exception
// if it can parse a valid date out of a substring of the full string given
// the mask
// so we have to check the most complete format first, then it fails with
// exception
private static final String[] W3CDATETIME_MASKS = {
"yyyy-MM-dd'T'HH:mm:ss.SSSz",
"yyyy-MM-dd't'HH:mm:ss.SSSz",
"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
"yyyy-MM-dd't'HH:mm:ss.SSS'z'",
"yyyy-MM-dd'T'HH:mm:ssz",
"yyyy-MM-dd't'HH:mm:ssz",
"yyyy-MM-dd'T'HH:mm:ss'Z'",
"yyyy-MM-dd't'HH:mm:ss'z'",
"yyyy-MM-dd'T'HH:mmz", // together with logic in the parseW3CDateTime they
"yyyy-MM'T'HH:mmz", // handle W3C dates without time forcing them to be GMT
"yyyy'T'HH:mmz",
"yyyy-MM-dd't'HH:mmz",
"yyyy-MM-dd'T'HH:mm'Z'",
"yyyy-MM-dd't'HH:mm'z'",
"yyyy-MM-dd",
"yyyy-MM",
"yyyy"
};

private static final String[] patterns_masks = {
"yyyy-MM-dd HH:mm:ss,SSS",
"yyyy-MM-dd HH:mm:ss.SSS",
"yyyy-MM-dd HH:mm:ss",
"yyyy-MM-dd HH:mm",
"yyyy-MM-dd",
"yyyy/MM/dd HH:mm:ss,SSS",
"yyyy/MM/dd HH:mm:ss.SSS",
"yyyy/MM/dd HH:mm:ss",
"yyyy/MM/dd HH:mm",
"yyyy/MM/dd",
"yyyyMMddHHmmss",
"yyyyMMdd",
"hh:mm:ss,SSS",
"hh:mm:ss.SSS",
"hh:mm:ss"
};

/**
* 修正 new Date() 函数返回的时间是北京时间.
* @since 2008-10-31
*/
public static void fixedChinaTimeZone() {
TimeZone userTimeZone = TimeZone.getTimeZone(System.getProperty("user.timezone"));
TimeZone chinaTimeZone = TimeZone.getTimeZone("Asia/Shanghai");
if (!chinaTimeZone.hasSameRules(userTimeZone)) {
TimeZone.setDefault(chinaTimeZone);
System.out.println("fixed current date:" + format(new Date(), "yyyy-MM-dd HH:mm:ss"));
}
}

/**
* get date string use pattern
*
* @param pattern
*            see {@link java.text.SimpleDateFormat}
* @return a date string
*/
public static String format(String pattern) {
return format(new Date(), pattern);
}

/**
* get date string use pattern
*
* @param pattern
*            see {@link java.text.SimpleDateFormat}
* @return a date string
*/
public static String format(Date date, String pattern) {
SimpleDateFormat dateFormater = new SimpleDateFormat(pattern);
//dateFormater.setTimeZone(TimeZone.getTimeZone("GMT+8")); // 2008-02-22 fixed by subchen
return dateFormater.format(date);
}

/**
* get current date and time string
*
* @return a local datetime string
*/
public static String getNowStr() {
return format(new Date(), "yyyy-MM-dd HH:mm:ss");
}

/**
* get current date string
*
* @return a local date string
*/
public static String getDateStr() {
return format(new Date(), "yyyy-MM-dd");
}

/**
* get current time string
*
* @return a local time string
*/
public static String getTimeStr() {
return format(new Date(), "HH:mm:ss");
}

/**
* @since 2008-01-02
*/
public static Calendar getCalendar(long millis) {
Calendar c = Calendar.getInstance();
c.setTimeInMillis(millis);
return c;
}

/**
* @since 2008-01-02
*/
public static Calendar getCalendar(Date date) {
Calendar c = Calendar.getInstance();
c.setTime(date);
return c;
}

/**
* @since 2008-01-02
*/
public static Date add(Date date, int field, int diff) {
Calendar c = getCalendar(date);
c.add(field, diff);
return c.getTime();
}

/**
* @since 2008-01-02
*/
public static Date add(int field, int diff) {
return add(new Date(), field, diff);
}

/**
* 得到与当前时间相差 diff 年的时间
*/
public static Date nextYears(int diff) {
return add(new Date(), Calendar.YEAR, diff);
}

/**
* 得到与当前时间相差 diff 年的时间
*/
public static Date nextYears(Date date, int diff) {
return add(date, Calendar.YEAR, diff);
}

/**
* 得到与当前时间相差 diff 年的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextYears(String sDate, int diff) {
return format(nextYears(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 得到与当前时间相差 diff 月的时间
*/
public static Date nextMonths(int diff) {
return add(new Date(), Calendar.MONTH, diff);
}

/**
* 得到与当前时间相差 diff 月的时间
*/
public static Date nextMonths(Date date, int diff) {
return add(date, Calendar.MONTH, diff);
}

/**
* 得到与当前时间相差 diff 月的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextMonths(String sDate, int diff) {
return format(nextMonths(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 得到与当前时间相差 diff 天的时间
*/
public static Date nextDays(int diff) {
return add(new Date(), Calendar.DATE, diff);
}

/**
* 得到与当前时间相差 diff 天的时间
*/
public static Date nextDays(Date date, int diff) {
return add(date, Calendar.DATE, diff);
}

/**
* 得到与当前时间相差 diff 天的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextDays(String sDate, int diff) {
return format(nextDays(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 得到与当前时间相差 diff 小时的时间
*/
public static Date nextHours(int diff) {
return add(new Date(), Calendar.HOUR, diff);
}

/**
* 得到与当前时间相差 diff 小时的时间
*/
public static Date nextHours(Date date, int diff) {
return add(date, Calendar.HOUR, diff);
}

/**
* 得到与当前时间相差 diff 小时的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextHours(String sDate, int diff) {
return format(nextHours(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 得到与当前时间相差 diff 分的时间
*/
public static Date nextMinutes(int diff) {
return add(new Date(), Calendar.MINUTE, diff);
}

/**
* 得到与当前时间相差 diff 分的时间
*/
public static Date nextMinutes(Date date, int diff) {
return add(date, Calendar.MINUTE, diff);
}

/**
* 得到与当前时间相差 diff 分的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextMinutes(String sDate, int diff) {
return format(nextMinutes(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 得到与当前时间相差 diff 秒的时间
*/
public static Date nextSeconds(int diff) {
return add(new Date(), Calendar.SECOND, diff);
}

/**
* 得到与当前时间相差 diff 秒的时间
*/
public static Date nextSeconds(Date date, int diff) {
return add(date, Calendar.SECOND, diff);
}

/**
* 得到与当前时间相差 diff 秒的时间 必须使用yyyy-MM-dd HH:mm:ss格式
*/
public static String nextSeconds(String sDate, int diff) {
return format(nextSeconds(parse(sDate), diff), "yyyy-MM-dd HH:mm:ss");
}

/**
* 清除时间，得到日期
* @since 2007-12-10
*/
public static Date clearTime(Date date) {
Calendar c = Calendar.getInstance();
c.setTime(date);
c.set(Calendar.HOUR_OF_DAY, 0);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
c.set(Calendar.MILLISECOND, 0);
return c.getTime();
}

/**
* 清除时间，得到日期
* @since 2007-12-10
*/
public static Date clearDate(Date date) {
Calendar c = Calendar.getInstance();
c.setTime(date);
c.set(Calendar.YEAR, 0);
c.set(Calendar.MONTH, 0);
c.set(Calendar.DATE, 0);
return c.getTime();
}

/**
* 计算 d1 - d2 的天数差
* @since 2007-12-10
*/
public static long diffDays(Date d1, Date d2) {
d1 = clearTime(d1);
d2 = clearTime(d2);
return (d1.getTime() - d2.getTime()) / (24 * 60 * 60 * 1000);
}

/**
* 计算 d1 - d2 的毫秒差
* @since 2007-12-10
*/
public static long diffMillis(Date d1, Date d2) {
return d1.getTime() - d2.getTime();
}

/**
* 计算 d1 - d2 的秒差
* @since 2007-12-10
*/
public static long diffSeconds(Date d1, Date d2) {
return (d1.getTime() - d2.getTime())/1000;
}
/**
* 得到 Calendar 类中的 Field Value.
* @see java.util.Calendar
* @since 2007-12-10
*/
public static int getCalendarField(Date date, int field) {
Calendar c = Calendar.getInstance();
c.setTime(date);
return c.get(field);
}

/**
* 得到当前时间
*/
public static Timestamp getTimestamp() {
return new Timestamp(System.currentTimeMillis());
}

public static Timestamp getTimestamp(Date date) {
return date == null ? null : new Timestamp(date.getTime());
}

/**
* 用指定的格式解析日期时间.
*
* @param datetime
*            时间字符串
* @param pattern
*            see {@link java.text.SimpleDateFormat}
* @throws UnhandledException
*/
public static Date parse(String datetime, String pattern) {
SimpleDateFormat sdf = new SimpleDateFormat(pattern);
sdf.setLenient(true);

ParsePosition pp = new ParsePosition(0);
Date d = sdf.parse(datetime, pp);
if (pp.getIndex() != datetime.length()) {
d = null;
}
return d;

}

/**
* Parses a Date out of a string using an array of masks. <p/> It uses the
* masks in order until one of them succedes or all fail. <p/>
*
* @param masks
*            array of masks to use for parsing the string
* @param sDate
*            string to parse for a date.
* @return the Date represented by the given string using one of the given
*         masks. It returns <b>null</b> if it was not possible to parse
*         the the string with any of the masks.
*/
private static Date parseUsingMask(String[] masks, String sDate) {
sDate = (sDate != null) ? sDate.trim() : null;
ParsePosition pp = null;
Date d = null;
for (int i = 0; d == null && i < masks.length; i++) {
DateFormat df = new SimpleDateFormat(masks[i]);
// df.setLenient(false);
df.setLenient(true);
try {
pp = new ParsePosition(0);
d = df.parse(sDate, pp);
if (pp.getIndex() != sDate.length()) {
d = null;
}
// System.out.println("pp["+pp.getIndex()+"]
// s["+sDate+"m["+masks[i]+"] d["+d+"]");
} catch (Exception e) {
// System.out.println("s: "+sDate+" m: "+masks[i]+" d: "+null);
// try next pattern
}
}
return d;
}

/**
* Parses a Date out of a String with a date in RFC822 format. <p/> It
* parsers the following formats:
* <ul>
* <li>"EEE, dd MMM yyyy HH:mm:ss z"</li>
* <li>"EEE, dd MMM yyyy HH:mm z"</li>
* <li>"EEE, dd MMM yy HH:mm:ss z"</li>
* <li>"EEE, dd MMM yy HH:mm z"</li>
* <li>"dd MMM yyyy HH:mm:ss z"</li>
* <li>"dd MMM yyyy HH:mm z"</li>
* <li>"dd MMM yy HH:mm:ss z"</li>
* <li>"dd MMM yy HH:mm z"</li>
* </ul>
* <p/> Refer to the java.text.SimpleDateFormat javadocs for details on the
* format of each element. <p/>
*
* @param sDate
*            string to parse for a date.
* @return the Date represented by the given RFC822 string. It returns
*         <b>null</b> if it was not possible to parse the given string
*         into a Date.
*
*/
public static Date parseRFC822(String sDate) {
int utIndex = sDate.indexOf(" UT");
if (utIndex > -1) {
String pre = sDate.substring(0, utIndex);
String post = sDate.substring(utIndex + 3);
sDate = pre + " GMT" + post;
}
return parseUsingMask(RFC822_MASKS, sDate);
}

/**
* Parses a Date out of a String with a date in W3C date-time format. <p/>
* It parsers the following formats:
* <ul>
* <li>"yyyy-MM-dd'T'HH:mm:ssz"</li>
* <li>"yyyy-MM-dd'T'HH:mmz"</li>
* <li>"yyyy-MM-dd"</li>
* <li>"yyyy-MM"</li>
* <li>"yyyy"</li>
* </ul>
* <p/> Refer to the java.text.SimpleDateFormat javadocs for details on the
* format of each element. <p/>
*
* @param sDate
*            string to parse for a date.
* @return the Date represented by the given W3C date-time string. It
*         returns <b>null</b> if it was not possible to parse the given
*         string into a Date.
*
*/
public static Date parseW3CDateTime(String sDate) {
// if sDate has time on it, it injects 'GTM' before de TZ displacement
// to
// allow the SimpleDateFormat parser to parse it properly
int tIndex = sDate.indexOf("T");
if (tIndex > -1) {
if (sDate.endsWith("Z")) {
sDate = sDate.substring(0, sDate.length() - 1) + "+00:00";
}
int tzdIndex = sDate.indexOf("+", tIndex);
if (tzdIndex == -1) {
tzdIndex = sDate.indexOf("-", tIndex);
}
if (tzdIndex > -1) {
String pre = sDate.substring(0, tzdIndex);
int secFraction = pre.indexOf(",");
if (secFraction > -1) {
pre = pre.substring(0, secFraction);
}
String post = sDate.substring(tzdIndex);
sDate = pre + "GMT" + post;
}
} else {
sDate += "T00:00GMT";
}
return parseUsingMask(W3CDATETIME_MASKS, sDate);
}

/**
* Parses a Date out of a String with a date in W3C date-time format or in a
* RFC822 format or in a humpic-default format. <p/> 用尝试多种格式解析日期时间,
* 修改自：http://www.koders.com/java/fidDBC85D14D02AA458CE8B8A25256E176EAC6EA748.aspx
* <p>
*
* @param sDate
*            string to parse for a date.
* @return the Date represented by the given W3C date-time string. It
*         returns <b>null</b> if it was not possible to parse the given
*         string into a Date.
*/
public static Date parse(String sDate) {
Date d = parseW3CDateTime(sDate);
if (d == null) {
d = parseRFC822(sDate);
}
if (d == null) {
d = parseUsingMask(patterns_masks, sDate);
}
if (d == null) {
try {
d = DateFormat.getInstance().parse(sDate);
} catch (ParseException e) {
d = null;
}
}
return d;
}

/**
* create a RFC822 representation of a date. <p/> Refer to the
* java.text.SimpleDateFormat javadocs for details on the format of each
* element. <p/>
*
* @param date
*            Date to parse
* @return the RFC822 represented by the given Date It returns <b>null</b>
*         if it was not possible to parse the date.
*/
public static String formatRFC822(Date date) {
SimpleDateFormat dateFormater = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss 'GMT'");
dateFormater.setTimeZone(TimeZone.getTimeZone("GMT"));
return dateFormater.format(date);
}

/**
* create a W3C Date Time representation of a date. <p/> Refer to the
* java.text.SimpleDateFormat javadocs for details on the format of each
* element. <p/>
*
* @param date
*            Date to parse
* @return the W3C Date Time represented by the given Date It returns
*         <b>null</b> if it was not possible to parse the date.
*/
public static String formatW3CDateTime(Date date) {
SimpleDateFormat dateFormater = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
dateFormater.setTimeZone(TimeZone.getTimeZone("GMT"));
return dateFormater.format(date);
}

/**
*
* 说明：获得两个时间的天数
* @param d1 开始时间
* @param d2 结束时间
* @return
*/
public static int getDays(Date d1,Date d2) {
return (int) ((d2.getTime() - d1.getTime()) / (3600L * 1000 * 24));
}

/**
*
* 说明：获得两个时间的小时数
* @param d1 开始时间
* @param d2 结束时间
* @return
*/
public static int getHours(Date d1,Date d2) {
return (int) ((d2.getTime() - d1.getTime()) / (3600L * 1000));
}

public static String formatDate(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy 年 MM 月 dd 日");
return sdf.format(date);
}

public static String formatTime(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH时mm分ss秒");
return sdf.format(date);
}

public static String formatTimeMonth(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("MM月dd日");
return sdf.format(date);
}

public static String formatTime2(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return sdf.format(date);
}
public static String getYear(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy");
return sdf.format(date);
}
public static Date getMaxTodayDate(){
String todayDateStr = format(new Date(), "yyyy-MM-dd 23:59:59");
return parse(todayDateStr, "yyyy-MM-dd HH:mm:ss");
}

public static Date getMinTodayDate() {
String todayDateStr = format(new Date(), "yyyy-MM-dd 00:00:00");
return parse(todayDateStr, "yyyy-MM-dd HH:mm:ss");
}

public static Date getMaxTodayDate(Date date){
String todayDateStr = format(date, "yyyy-MM-dd 23:59:59");
return parse(todayDateStr, "yyyy-MM-dd HH:mm:ss");
}

public static Date getMinTodayDate(Date date) {
String todayDateStr = format(date, "yyyy-MM-dd 00:00:00");
return parse(todayDateStr, "yyyy-MM-dd HH:mm:ss");
}

public static Date getCurrentTodayDate(Date date){
String todayDateStr = format(date, "yyyy-MM-dd HH:mm:ss");
return parse(todayDateStr, "yyyy-MM-dd HH:mm:ss");
}

public static void main(String[] args) {
System.out.println(DateHelper.format(new Date(), "yyyyMMddHHmm"));
System.out.println(DateHelper.getYear(new Date()));
//System.out.println(DateHelper.parse(datetime, pattern));
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.println("测试下:   "+DateHelper.diffDays(DateHelper.parse("2011-09-07 23:36:30"), new Date()));
System.out.println("测试下:   "+DateHelper.diffDays(DateHelper.parse("2011-10-22 23:36:30"), new Date()));
Date t = DateHelper.parse("2009-03-04");
System.out.println(sdf.format(t));
Date d = nextWorkDays(new Date(), 3);
System.out.println("date==================="+sdf.format(d));
System.out.println("date==================="+sdf.format(DateHelper.nextDays(7)));
//nextDays("2011-03-25",)

String time = "01:20";
System.out.println(DateHelper.getTime2Int(DateHelper.parse(time, "HH:mm")));
//System.out.println(DateHelper.f);
System.out.println("date==================="+diffDays(parse("2011-09-01"),new Date()));
StringBuffer sb = new StringBuffer("");
for(int x = 9; x < 19;x++) {
for(int i = 0;i < 60;i++) {
sb.append("\"");
if(x < 10) sb.append("0");
sb.append(x).append(":");
if(i < 10) sb.append("0");
sb.append(i).append("\",");
}
}
System.out.println(sb.toString());
}

/**
*
* 说明：返回当前的diff个工作日后的时间--暂时只排除周六周日
* sunday-1  thursday-5 saturday-7
* @param date
* @param diff
* @return
*/
public static Date nextWorkDays(Date date, int diff) {
//得到当前的时间是星期几
Calendar c = Calendar.getInstance();
c.setTime(date);
Integer dayOfWeek = c.get(Calendar.DAY_OF_WEEK);
int perDays = 0;
if(!dayOfWeek.equals(1)&&!dayOfWeek.equals(7)) {
perDays = 7-dayOfWeek;
}
diff = diff-perDays;
int allDiffDays = 0;
if(diff > 0) {
int numOfWeek = diff/5;
int restDays = diff%5;
allDiffDays = numOfWeek*7+restDays;
if(dayOfWeek.equals(1)) {
allDiffDays = allDiffDays+1;
} else {
allDiffDays = allDiffDays+2+perDays;
}
} else {
return nextDays(date, diff+perDays);
}
return nextDays(date, allDiffDays);
}
/**
* 得到本周周一
* @param w 0: 表示为本周，-1：表示为上周 ，1：表示为下周，以此类推
* @return yyyy-MM-dd
*/
public static String getMondayOfThisWeek(int w) {
Calendar c = Calendar.getInstance();
int dayofweek = c.get(Calendar.DAY_OF_WEEK) - 1;
if (dayofweek == 0)
dayofweek = 7;
c.add(Calendar.DATE, -dayofweek + 1 + 7 * w);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
return sdf.format(c.getTime());
}

/**
*得到本周周日
* @param w 0: 表示为本周，-1：表示为上周 ，1：表示为下周，以此类推
* @return yyyy-MM-dd
*/
public static String getSundayOfThisWeek(int w) {
Calendar c = Calendar.getInstance();
int dayofweek = c.get(Calendar.DAY_OF_WEEK) - 1;
if (dayofweek == 0)
dayofweek = 7;
c.add(Calendar.DATE, -dayofweek + 7 + 7 * w);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
return sdf.format(c.getTime());
}
/**
* 得到本月最后一天
* @param dt 某个月的某一天
* @return
*/
public static String getLastDateOfMonth(Date dt) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
cal.setTime(dt);
int days = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_MONTH, days);
String result = format.format(cal.getTime());
//System.out.println("一个月最后一天" + result);
return result;
}

/**
* 得到本月第一天
* @param dt 某个月的某一天
* @return
*/
public static String getFristDateOfMonth(Date dt) {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
Calendar cal = Calendar.getInstance();
cal.setTime(dt);
int days = cal.getActualMinimum(Calendar.DAY_OF_MONTH);
cal.set(Calendar.DAY_OF_MONTH, days);
String result = format.format(cal.getTime());
//System.out.println("一个月第一天" + result);
return result;
}

/**
* 以YYYY-MM-DD HH:MM:SS格式返回系统日期时间
*
* @return 系统日期时间 add by zg 2003-12-9
*/
public static String getSysDateStringYMDHMS() {
String date = "";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
java.util.Date dd = new java.util.Date();
date = sdf.format(dd);

return date;
}

/**
* 以yyyyMMddHHmmss格式返回系统日期时间
*
* @return 系统日期时间 add by zg 2004-09-25
*/
public static String getSysDateStringYMDHMS2() {
String date = "";
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmss");
java.util.Date dd = new java.util.Date();
date = sdf.format(dd);

return date;
}
}