Java日期处理工具类DateUtils详解

本文实例为大家分享了Java日期处理工具类DateUtils的具体代码，供大家参考，具体内容如下

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

/**
 * <日期时间处理工具类>
 */
public class DateUtils { 

 /**
  * Date format pattern this is often used.
  */
 public static final String PATTERN_YMD = "yyyy-MM-dd"; 

 /**
  * Date format pattern this is often used.
  */
 public static final String PATTERN_YMDHMS="yyyy-MM-dd HH:mm:ss"; 

 /**
  * Formats the given date according to the YMD pattern.
  *
  * @param date The date to format.
  * @return An YMD formatted date string.
  *
  * @see #PATTERN_YMD
  */
 public static String formatDate(Date date) {
  return formatDate(date, PATTERN_YMD);
 } 

 /**
  * Formats the given date according to the specified pattern. The pattern
  * must conform to that used by the {@link SimpleDateFormat simple date
  * format} class.
  *
  * @param date The date to format.
  * @param pattern The pattern to use for formatting the date.
  * @return A formatted date string.
  *
  * @throws IllegalArgumentException If the given date pattern is invalid.
  *
  * @see SimpleDateFormat
  */
 public static String formatDate(Date date, String pattern) {
  if (date == null)
   throw new IllegalArgumentException("date is null");
  if (pattern == null)
   throw new IllegalArgumentException("pattern is null"); 

  SimpleDateFormat formatter = new SimpleDateFormat(pattern);
  return formatter.format(date);
 } 

 /**
  * Parses a date value. The format used for parsing the date value are retrieved from
  * the default PATTERN_YMD.
  *
  * @param dateValue the date value to parse
  *
  * @return the parsed date
  *
  * @throws IllegalArgumentException If the given dateValue is invalid.
  */
 public static Date parseDate(String dateValue) {
  return parseDate(dateValue, null);
 } 

 /**
  * Parses the date value using the given date format.
  *
  * @param dateValue the date value to parse
  * @param dateFormat the date format to use
  *
  * @return the parsed date. if parse is failed , return null
  *
  * @throws IllegalArgumentException If the given dateValue is invalid.
  */
 public static Date parseDate(String dateValue, String dateFormat) {
  if (dateValue == null) {
   throw new IllegalArgumentException("dateValue is null");
  }
  if (dateFormat == null) {
   dateFormat = PATTERN_YMD;
  } 

  SimpleDateFormat df = new SimpleDateFormat(dateFormat);
  Date result = null;
  try {
   result = df.parse(dateValue);
  }
  catch (ParseException pe) {
   pe.printStackTrace();// 日期型字符串格式错误
  }
  return result;
 } 

 /**
  * Adds a number of years to a date returning a new object.
  * The original date object is unchanged.
  *
  * @param date the date, not null
  * @param amount the amount to add, may be negative
  * @return the new date object with the amount added
  * @throws IllegalArgumentException if the date is null
  */
 public static Date addYears(Date date, int amount) {
  return add(date, Calendar.YEAR, amount);
 } 

 /**
  * Adds a number of years to a timestamp returning a new object.
  * The original timestamp object is unchanged.
  *
  * @param timestamp the timestamp, not null
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  * @throws IllegalArgumentException if the timestamp is null
  */
 public static Timestamp addYears(Timestamp timestamp, int amount) {
  return add(timestamp, Calendar.YEAR, amount);
 } 

 //-----------------------------------------------------------------------
 /**
  * Adds a number of months to a date returning a new object.
  * The original date object is unchanged.
  *
  * @param date the date, not null
  * @param amount the amount to add, may be negative
  * @return the new date object with the amount added
  * @throws IllegalArgumentException if the date is null
  */
 public static Date addMonths(Date date, int amount) {
  return add(date, Calendar.MONTH, amount);
 } 

 /**
  * Adds a number of months to a timestamp returning a new object.
  * The original timestamp object is unchanged.
  *
  * @param timestamp the timestamp, not null
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  * @throws IllegalArgumentException if the timestamp is null
  */
 public static Timestamp addMonths(Timestamp timestamp, int amount) {
  return add(timestamp, Calendar.MONTH, amount);
 } 

 //-----------------------------------------------------------------------
 /**
  * Adds a number of days to a date returning a new object.
  * The original date object is unchanged.
  *
  * @param date the date, not null
  * @param amount the amount to add, may be negative
  * @return the new date object with the amount added
  * @throws IllegalArgumentException if the date is null
  */
 public static Date addDays(Date date, int amount) {
  return add(date, Calendar.DATE, amount);
 } 

 /**
  * Adds a number of days to a timestamp returning a new object.
  * The original timestamp object is unchanged.
  *
  * @param timestamp the timestamp, not null
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  * @throws IllegalArgumentException if the timestamp is null
  */
 public static Timestamp addDays(Timestamp timestamp, int amount) {
  return add(timestamp, Calendar.DATE, amount);
 } 

 //-----------------------------------------------------------------------
 /**
  * Adds a number of minutes to a timestamp returning a new object.
  * The original timestamp object is unchanged.
  *
  * @param timestamp the timestamp, not null
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  * @throws IllegalArgumentException if the timestamp is null
  */
 public static Timestamp addMinutes(Timestamp timestamp, int amount) {
  return add(timestamp, Calendar.MINUTE, amount);
 } 

 /**
  * Adds a number of days to current time returning a new object.
  *
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  */
 public static Timestamp addDays(int amount) {
  Calendar c = Calendar.getInstance();
  c.add(Calendar.DATE, amount);
  return new Timestamp(c.getTimeInMillis());
 } 

 //-----------------------------------------------------------------------
 /**
  * Adds to a date returning a new object.
  * The original date object is unchanged.
  *
  * @param date the date, not null
  * @param calendarField the calendar field to add to
  * @param amount the amount to add, may be negative
  * @return the new date object with the amount added
  * @throws IllegalArgumentException if the date is null
  */
 private static Date add(Date date, int calendarField, int amount) {
  if (date == null) {
   throw new IllegalArgumentException("The date must not be null");
  }
  Calendar c = Calendar.getInstance();
  c.setTime(date);
  c.add(calendarField, amount);
  return c.getTime();
 } 

 /**
  * Adds to a timestamp returning a new object.
  * The original timestamp object is unchanged.
  *
  * @param timestamp the timestamp, not null
  * @param calendarField the calendar field to add to
  * @param amount the amount to add, may be negative
  * @return the new timestamp object with the amount added
  * @throws IllegalArgumentException if the timestamp is null
  */
 private static Timestamp add(Timestamp timestamp, int calendarField, int amount) {
  if (timestamp == null) {
   throw new IllegalArgumentException("The timestamp must not be null");
  }
  Calendar c = Calendar.getInstance();
  c.setTime(timestamp);
  c.add(calendarField, amount);
  return new Timestamp(c.getTimeInMillis());
 } 

 /**
  * <生成最小的当天日期值>
  * @return 最小的当天日期值
  */
 public static Timestamp now() {
  Calendar c = Calendar.getInstance();
  c.set(Calendar.HOUR_OF_DAY, 0);
  c.set(Calendar.MINUTE, 0);
  c.set(Calendar.SECOND, 0);
  c.set(Calendar.MILLISECOND, 0);
  return new Timestamp(c.getTimeInMillis());
 } 

 /** This class should not be instantiated. */
 private DateUtils() {
 }
}

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