用途：一些与时间相关的处理
功能：
1.获取当前时间 格式---->2019-08-04 13:30:29：getNowTime
2.将一个日期字符串转换成Data对象 string–>date：stringToDate
3将date转换成字符串 date—>string：dateToString
4.获取指定日期 ，返回值为： “周日”, “周一”, “周二”, “周三”, “周四”, “周五”, “周六”：getWeekOfDate
5.获取指定日期对应周几的序列：getIndexWeekOfDate
6.获取当前月份：getNowMonth
7.获取当前月号：getNowDay
8.获取当前年份：getNowYear
9.获取本月份的天数：getNowDaysOfMonth
10.获取指定月份的天数：daysOfMonth
11.计算两个日期之间的年份差距：getYearGapOfDates
12：计算两个日期之间的月份差距：getMonthGapOfDates
13.计算两个日期之间的天数差：getDaysGapOfDates
public class DateUtils {
public static final long ONE_DAY_MILLS = 3600000 * 24;
private DateUtils() {
}
/**
* 日期格式 enum(枚举类型):一组类似的值包含到一种类型当中。而这种枚举类型的名称则会被定义成独一无二的类型描述符 -->为申明的变量提供更大的取值范围
*/
public enum DateFormat {
/**
* 格式："yyyy-MM-dd HH:mm:ss"
*/
ALL_TIME {
public String getValue() {
return "yyyy-MM-dd HH:mm:ss";
}
},
/**
* 格式："yyyy-MM-dd HH:mm"
*/
ONLY_MINUTE {
public String getValue() {
return "yyyy-MM-dd HH:mm";
}
},
/**
* 格式："yyyy-MM-dd HH"
*/
ONLY_HOUR {
public String getValue() {
return "yyyy-MM-dd HH";
}
},
/**
* 格式："yyyy-MM-dd"
*/
ONLY_DAY {
public String getValue() {
return "yyyy-MM-dd";
}
},
/**
* 格式："yyyy-MM"
*/
ONLY_MONTH {
public String getValue() {
return "yyyy-MM";
}
},
/**
* 格式："MM-dd"
*/
ONLY_MONTH_DAY {
public String getValue() {
return "MM-dd";
}
},
/**
* 格式："MM-dd HH:mm"
*/
ONLY_MONTH_SEC {
public String getValue() {
return "MM-dd HH:mm";
}
},
/**
* 格式："HH:mm:ss"
*/
ONLY_TIME {
public String getValue() {
return "HH:mm:ss";
}
},
/**
* 格式："HH:mm"
*/
ONLY_HOUR_MINUTE {
public String getValue() {
return "HH:mm";
}
};
public abstract String getValue();
}
/**
* 获取当前时间 格式---->2019-08-04 13:30:29
*/
public static String getNowTime(DateFormat format) {
String nowtime = null;
Calendar calendar = Calendar.getInstance();
Date dateNow = calendar.getTime();
SimpleDateFormat sdf = new SimpleDateFormat(format.getValue(), Locale.CHINA);
nowtime = sdf.format(dateNow);
return nowtime;
}
/**
* 将一个日期字符串转换成Data对象 string-->date
*
* @param dateString 日期字符串
* @param format 转换格式
* @return
*/
public static Date stringToDate(String dateString, DateFormat format) {
Date date = null;
SimpleDateFormat sdf = new SimpleDateFormat(format.getValue(), Locale.CHINA);
try {
date = sdf.parse(dateString);
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}
/**
* 将date转换成字符串 date--->string
*
* @param date 日期
* @param format 日期目标格式
* @return
*/
public static String dateToString(Date date, DateFormat format) {
String string = "";
SimpleDateFormat sdf = new SimpleDateFormat(format.getValue(), Locale.CHINA);
string = sdf.format(date);
return string;
}
/**
* 获取指定日期
*
* @param date 指定日期
* @return 返回值为： "周日", "周一", "周二", "周三", "周四", "周五", "周六"
*/
public static String getWeekOfDate(Date date) {
String[] weekDays = {"周日", "周一", "周二", "周三", "周四", "周五", "周六"};
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
int week = calendar.get(Calendar.DAY_OF_WEEK) - 1;
if (week < 0)
week = 0;
return weekDays[week];
}
/**
* 获取指定日期对应周几的序列
*
* @param date 指定日期
* @return 周一：1 周二：2 周三：3 周四：4 周五：5 周六：6 周日：7
*/
public static int getIndexWeekOfDate(Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
int index = calendar.get(Calendar.DAY_OF_WEEK);
if (index == 1) {
return 7;
} else {
return --index;
}
}
/**
* 获取当前月份
*/
public static int getNowMonth() {
Calendar calendar = Calendar.getInstance();
return calendar.get(Calendar.MONTH) + 1;
}
/**
* 获取当前月号
*/
public static int getNowDay() {
Calendar calendar = Calendar.getInstance();
return calendar.get(Calendar.DATE);
}
/**
* 获取当前年份
*/
public static int getNowYear() {
Calendar calendar = Calendar.getInstance();
return calendar.get(Calendar.YEAR);
}
/**
* 获取本月份的天数
*/
public static int getNowDaysOfMonth() {
Calendar calendar = Calendar.getInstance();
return daysOfMonth(calendar.get(Calendar.YEAR), calendar.get(Calendar.DATE) + 1);
}
/**
* 计算两个日期之间的年份差距
*
* @param firstDate
* @param secondDate
* @return
*/
public static int getYearGapOfDates(Date firstDate, Date secondDate) {
if (firstDate == null || secondDate == null) {
return 0;
}
Calendar helpCalendar = Calendar.getInstance();
helpCalendar.setTime(firstDate);
int firstYear = helpCalendar.get(Calendar.YEAR);
helpCalendar.setTime(secondDate);
int secondYear = helpCalendar.get(Calendar.YEAR);
return secondYear - firstYear;
}
/**
* 计算两个日期之间的天数差
*
* @param startDate
* @param endDate
* @return
*/
public static int getDaysGapOfDates(Date startDate, Date endDate) {
int date = 0;
if (startDate != null && endDate != null) {
date = getDaysBetween(startDate, endDate);
}
return date;
}
/**
* 计算两个日期之间的月份差距
*
* @param firstDate
* @param secondDate
* @return
*/
public static int getMonthGapOfDates(Date firstDate, Date secondDate) {
if (firstDate == null || secondDate == null) {
return 0;
}
return (int) ((secondDate.getTime() - firstDate.getTime())
/ ONE_DAY_MILLS / 30);
}
/**
* 获取指定月份的天数
*
* @param year 年份
* @param month 月份
* @return 对应天数
*/
public static int daysOfMonth(int year, int month) {
switch (month) {
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
return 31;
case 4:
case 6:
case 9:
case 11:
return 30;
case 2:
if ((year % 4 == 0 && year % 100 == 0) || year % 400 != 0) {
return 29;
} else {
return 28;
}
default:
return -1;
}
}
private static int getDaysBetween(Date startDate, Date endDate) {
return (int) ((endDate.getTime() - startDate.getTime()) / ONE_DAY_MILLS);
}
}
