java 的日期处理函数
Calendar time = Calendar.getInstance();
time.clear();
time.set(Calendar.YEAR, Integer.parseInt(year));
time.set(Calendar.MONTH, Integer.parseInt(month) - 1 - 1);// 注意,Calendar对象默认一月为0
int cday = time.getActualMaximum(Calendar.DAY_OF_MONTH);// 本月份的天数
preDate = year + "-" + (Integer.parseInt(month) - 1) + "-" + cday;
this.month = Integer.parseInt(month);// 为了页面显示
this.premonth = this.month - 1;// 为了页面显示
===================================================================
public class DateUtil {
public static final String ISO_8601_PATTERN = "yyyy-MM-dd'T'HH:mm:ssZ";
public static final String SHORT_DATE_ISO_8601_PATTERN = "yyyy-MM-dd";
public static final String SHORT_DATE_TIME_ISO_8601_PATTERN = "yyyy-MM-dd HH:mm:ss";
public static int compareTo(Date date1, Date date2) {
// Workaround for bug in JDK 1.5.x. This bug is fixed in JDK 1.5.07. See
// http://bugs.sun.com/bugdatabase/view_bug.do;:YfiG?bug_id=6207898 for
// more information.
if ((date1 != null) && (date2 == null)) {
return -1;
} else if ((date1 == null) && (date2 != null)) {
return 1;
} else if ((date1 == null) && (date2 == null)) {
return 0;
}
long time1 = date1.getTime();
long time2 = date2.getTime();
if (time1 == time2) {
return 0;
} else if (time1 < time2) {
return -1;
} else {
return 1;
}
}
public static boolean equals(Date date1, Date date2) {
if (compareTo(date1, date2) == 0) {
return true;
} else {
return false;
}
}
public static boolean equals(Date date1, Date date2,
boolean ignoreMilliseconds) {
if (!ignoreMilliseconds) {
return equals(date1, date2);
}
long time1 = 0;
if (date1 != null) {
time1 = date1.getTime() / Time.SECOND;
}
long time2 = 0;
if (date2 != null) {
time2 = date2.getTime() / Time.SECOND;
}
if (time1 == time2) {
return true;
} else {
return false;
}
}
public static String getCurrentDate(String pattern, Locale locale) {
return getDate(new Date(), pattern, locale);
}
public static String getCurrentDate(String pattern, Locale locale,
TimeZone timeZone) {
return getDate(new Date(), pattern, locale, timeZone);
}
public static String getDate(Date date, String pattern, Locale locale) {
DateFormat dateFormat = new SimpleDateFormat(pattern, locale);
return dateFormat.format(date);
}
public static String getDate(Date date, String pattern, Locale locale,
TimeZone timeZone) {
DateFormat dateFormat = new SimpleDateFormat(pattern, locale);
dateFormat.setTimeZone(timeZone);
return dateFormat.format(date);
}
public static int getDaysBetween(Date startDate, Date endDate,
TimeZone timeZone) {
int offset = timeZone.getRawOffset();
Calendar startCal = new GregorianCalendar(timeZone);
startCal.setTime(startDate);
startCal.add(Calendar.MILLISECOND, offset);
Calendar endCal = new GregorianCalendar(timeZone);
endCal.setTime(endDate);
endCal.add(Calendar.MILLISECOND, offset);
int daysBetween = 0;
while (CalendarUtil.beforeByDay(startCal.getTime(), endCal.getTime())) {
startCal.add(Calendar.DAY_OF_MONTH, 1);
daysBetween++;
}
return daysBetween;
}
public static DateFormat getISOFormat() {
return getISOFormat(StringPool.BLANK);
}
public static DateFormat getISOFormat(String text) {
String pattern = StringPool.BLANK;
if (text.length() == 8) {
pattern = "yyyyMMdd";
} else if (text.length() == 12) {
pattern = "yyyyMMddHHmm";
} else if (text.length() == 13) {
pattern = "yyyyMMdd'T'HHmm";
} else if (text.length() == 14) {
pattern = "yyyyMMddHHmmss";
} else if (text.length() == 15) {
pattern = "yyyyMMdd'T'HHmmss";
} else if ((text.length() > 8) && (text.charAt(8) == 'T')) {
pattern = "yyyyMMdd'T'HHmmssz";
} else {
pattern = "yyyyMMddHHmmssz";
}
return new SimpleDateFormat(pattern);
}
public static DateFormat getISO8601Format() {
return new SimpleDateFormat(ISO_8601_PATTERN);
}
public static DateFormat getUTCFormat() {
return getUTCFormat(StringPool.BLANK);
}
public static DateFormat getUTCFormat(String text) {
String pattern = StringPool.BLANK;
if (text.length() == 8) {
pattern = "yyyyMMdd";
} else if (text.length() == 12) {
pattern = "yyyyMMddHHmm";
} else if (text.length() == 13) {
pattern = "yyyyMMdd'T'HHmm";
} else if (text.length() == 14) {
pattern = "yyyyMMddHHmmss";
} else if (text.length() == 15) {
pattern = "yyyyMMdd'T'HHmmss";
} else {
pattern = "yyyyMMdd'T'HHmmssz";
}
DateFormat dateFormat = new SimpleDateFormat(pattern);
dateFormat.setTimeZone(TimeZone.getTimeZone(StringPool.UTC));
return dateFormat;
}
public static Date newDate() {
return new Date();
}
public static Date newDate(long date) {
return new Date(date);
}
//
public static String getFirstDayOfTheYear(int year) {
String formateStr = year + "-01-01";
String str_date = DateUtil
.getDate(new Date(), formateStr, Locale.CHINA);
return str_date;
}
public static String getLastDayOfTheYear(int year) {
String formateStr = year + "-12-31";
String str_date = DateUtil
.getDate(new Date(), formateStr, Locale.CHINA);
return str_date;
}
public static String getFirstDayOfTheMonth(int year, int month) {
Calendar calendar = Calendar.getInstance();
calendar.set(year, month, 1);
calendar.getTime();
String formateStr = "yyyy-MM-01";
return DateUtil.getDate(calendar.getTime(), formateStr, Locale.CHINA);
}
public static String getLastDayOfTheMonth(int year, int month) {
Calendar calendar = Calendar.getInstance();
calendar.set(year, month, 1);
//下个月第一号 减一
calendar.add(Calendar.MONTH, 1);
calendar.add(Calendar.DATE, -1);
String formateStr = "yyyy-MM-dd";
return DateUtil.getDate(calendar.getTime(), formateStr, Locale.CHINA);
}
public static void main(String[] args) {
System.out.println(DateUtil.getLastDayOfTheMonth(2007,Calendar.FEBRUARY));
}
}
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