java DateUtil日期工具类，获取当前日期几天前的日期，一周前的日期，两日期间周数

谁践踏了优雅 2023-10-17 21:40 40阅读 0赞

import java.util.Calendar;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
  
  
  
  
public class DateUtil\{  
  
  
/\*\*  
\* 获取指定日期间隔天数的起始值  
\* @param date  
\* @param pattern  
\* @param num  
\* @return  
\*/  
public static String getDateStartNum(String date, String pattern, int num)\{  
Calendar cal = Calendar.getInstance();  
cal.setTime(stringToDate(date, pattern));  
cal.add(Calendar.DATE, num);  
return dateToString(cal.getTime(), pattern);  
\}  
  
  
/\*\*  
\* 获取当前日期的几天前或几天后日期  
\* @return  
\*/  
public static String getCurrentBeforeNum(String pattern, int num)\{  
Calendar cal = Calendar.getInstance();  
cal.setTime(new Date());  
cal.add(Calendar.DATE, num);  
return dateToString(cal.getTime(), pattern);  
\}  
  
  
/\*\*  
\* 将日期字符串转化为日期  
\*  
\* @param date 日期字符串  
\* @param pattern 日期格式  
\* @return  
\*/  
public static Date stringToDate(String date, String pattern) \{  
Date myDate = null;  
if (date != null) \{  
try \{  
myDate = getDateFormat(pattern).parse(date);  
\} catch (Exception e) \{  
e.printStackTrace();  
\}  
\}  
return myDate;  
\}  
/\*\*  
\* 将日期转化为日期字符串  
\*  
\* @param date 日期  
\* @param pattern 日期格式  
\* @return  
\*/  
public static String dateToString(Date date, String pattern) \{  
String dateString = null;  
if (date != null) \{  
try \{  
dateString = getDateFormat(pattern).format(date);  
\} catch (Exception e) \{  
e.printStackTrace();  
\}  
\}  
return dateString;  
\}  
  
/\*\*  
\* 获取SimpleDateFormat  
\*  
\* @param pattern 日期格式  
\* @return  
\*/  
public static SimpleDateFormat getDateFormat(String pattern) \{  
if (pattern != null && pattern.equals("")) \{  
throw new RuntimeException("无效日期格式");  
\}  
SimpleDateFormat dateFormat = new SimpleDateFormat(pattern);  
return dateFormat;  
\}

/**
     * 获取间隔日期内的所有周
     * @param dBegin
     * @param dEnd
     * @return
     */
    public static  List<Integer> findWeek(Date dBegin, Date dEnd) {
        List<Integer> week = new ArrayList<>();
        Calendar calendar = Calendar.getInstance();
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        calendar.setTime(dBegin);
        int startWeek = calendar.get(Calendar.WEEK_OF_YEAR);
        calendar.setTime(dEnd);
        int endWeek = calendar.get(Calendar.WEEK_OF_YEAR);
        for (; startWeek <= endWeek; startWeek ++) {
            week.add(startWeek);
        }
        return week;
    }

public static void main(String\[\] args) \{  
// 调用 七天前的日期  
System.out.print(DateUtil.getCurrentBeforeNum("yyyy-MM-dd", -7));  
\}  
  
  
  
  
\}