Java常用日期辅助类

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
* 日期辅助类
* @author yushibo
*/
public final class DateHelper {

private static DateHelper instance = new DateHelper();

public static DateHelper getInstance() {
return instance;
}

/**
* 日期标值枚举
* @author SuZhongQing
*/
public enum DateRangeFlag {
THIS_DAY, THIS_WEEK, THIS_MONTH
}

/**
* 根据指定格式的日期字符串获得日期
* @param dateStr 日期字符串 格式如：(yyyy-MM-dd)
* @return 日期
*/
public static Date getDateByString(String dateStr) {
String[] elements = dateStr.split("-");
if (elements.length != 3) {
return new Date();
}

Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, Integer.parseInt(elements[0]));
cal.set(Calendar.MONTH, Integer.parseInt(elements[1]) - 1);
cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(elements[2]));

return cal.getTime();
}

/**
* 根据日期，返回指定格式的日期字符串"yyyy-MM-dd"
* @param date
* @return 指定格式的日期字符串
*/
public static String getFormatString(Date date) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
return date == null ? "" : sdf.format(date);
}

/**
* 方法名：getFullFormateString
* 方法描述：获取包含小时、分钟、秒的时间字符串 "yyyy-MM-dd HH:mm:ss"
* @param date 日期
* @return 指定格式的日期字符串
*/
public static String getFullFormateString(Date date){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return date == null ? "" : sdf.format(date);
}

/**
*
* 方法描述：获取当前日期包含小时、分钟、秒的时间字符串 "yyyy-MM-dd HH:mm:ss"
* @param date 日期
* @return 指定格式的日期字符串
*/
public static String getNowFullFormateString(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return sdf.format(new Date());
}


/**
* 根据指定的日期范围标值，返回指定的开始日期和结束日期
*
* @param date
*            日期
* @param flag
*            日期范围标值
* @return 日期数组，第一个元素为开始日期，第二个元素为结束日期
*/
public static Date[] getDatesByFlag(Date date, DateRangeFlag flag) {
Date[] dates = new Date[2];
Calendar beginCal = Calendar.getInstance();
Calendar endCal = Calendar.getInstance();
beginCal.setTime(date);
endCal.setTime(date);

switch (flag) {
case THIS_DAY:
beginCal.set(Calendar.DAY_OF_MONTH, beginCal
.get(Calendar.DAY_OF_MONTH) - 1);
beginCal.set(Calendar.HOUR_OF_DAY, 0);
beginCal.set(Calendar.MINUTE, 0);
beginCal.set(Calendar.SECOND, 0);

endCal.set(Calendar.DAY_OF_MONTH,
endCal.get(Calendar.DAY_OF_MONTH) - 1);
endCal.set(Calendar.HOUR_OF_DAY, 23);
endCal.set(Calendar.MINUTE, 59);
endCal.set(Calendar.SECOND, 59);
dates[0] = beginCal.getTime();
dates[1] = endCal.getTime();
break;

case THIS_WEEK:
beginCal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
beginCal.set(beginCal.get(Calendar.YEAR), beginCal
.get(Calendar.MONTH),
beginCal.get(Calendar.DAY_OF_MONTH) - 7);
beginCal.set(Calendar.HOUR_OF_DAY, 0);
beginCal.set(Calendar.MINUTE, 0);
beginCal.set(Calendar.SECOND, 0);

endCal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
endCal.set(endCal.get(Calendar.YEAR), endCal.get(Calendar.MONTH),
endCal.get(Calendar.DAY_OF_MONTH) - 1);
endCal.set(Calendar.HOUR_OF_DAY, 23);
endCal.set(Calendar.MINUTE, 59);
endCal.set(Calendar.SECOND, 59);

dates[0] = beginCal.getTime();
dates[1] = endCal.getTime();
break;

case THIS_MONTH:
beginCal.set(Calendar.MONTH, beginCal.get(Calendar.MONTH) - 1);
beginCal.set(beginCal.get(Calendar.YEAR), beginCal
.get(Calendar.MONTH), 1);
beginCal.set(Calendar.HOUR_OF_DAY, 0);
beginCal.set(Calendar.MINUTE, 0);
beginCal.set(Calendar.SECOND, 0);

endCal.set(Calendar.MONTH, endCal.get(Calendar.MONTH));
endCal.set(Calendar.DAY_OF_MONTH, -1);
endCal.set(Calendar.HOUR_OF_DAY, 23);
endCal.set(Calendar.MINUTE, 59);
endCal.set(Calendar.SECOND, 59);

dates[0] = beginCal.getTime();
dates[1] = endCal.getTime();
break;
}
return dates;
}

public static DateRangeFlag getDateRangeEnum(int dateFlag) {
switch (dateFlag) {
case 2:
return DateRangeFlag.THIS_WEEK;
case 3:
return DateRangeFlag.THIS_MONTH;

default:
return DateRangeFlag.THIS_DAY;
}
}

public static Date getBeginDate(Date beginDate) {
Calendar cal = Calendar.getInstance();
cal.setTime(beginDate);
cal.set(Calendar.DAY_OF_MONTH, cal.get(Calendar.DAY_OF_MONTH));

cal.set(Calendar.HOUR_OF_DAY, 0);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
return cal.getTime();
}

public static Date getEndDate(Date endDate) {
Calendar cal = Calendar.getInstance();
cal.setTime(endDate);

cal.set(Calendar.DAY_OF_MONTH, cal.get(Calendar.DAY_OF_MONTH));
cal.set(Calendar.HOUR_OF_DAY, 23);
cal.set(Calendar.MINUTE, 59);
cal.set(Calendar.SECOND, 59);
return cal.getTime();
}

/**
* 返回当前时间在当年是第几周
**/
public static int getWeekOfYear(){
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
return cal.get(Calendar.WEEK_OF_YEAR)-1;
}

/**
* @param flag  true:返回上周第一天， false：返回上周最后一天
* 返回上周的开始日期或结束日期
**/
public static String getFirstDateOfPreWeek(boolean flag){
Calendar cal = Calendar.getInstance();
//获取当前时间
long today = cal.getTimeInMillis();
//设定周一是每周的第一天
cal.setFirstDayOfWeek(Calendar.MONDAY);
//得到当天处在当周的第几天，周一是当周的第一天
int dayNum = cal.get(Calendar.DAY_OF_WEEK)-1;
// System.out.println(dayNum);

if(dayNum == 0){
if(flag){
cal.setTimeInMillis(today - (13 - dayNum) * 24 * 60 * 60 * 1000);
}else{
cal.setTimeInMillis(today - (7 - dayNum) * 24 * 60 * 60 * 1000);
}
}else if(dayNum >= 1 && dayNum < 7){
if(flag){
cal.setTimeInMillis(today - (dayNum - 1 + 7) * 24 * 60 * 60 * 1000);
    }else{
    cal.setTimeInMillis(today + (7 - dayNum - 7) * 24 * 60 * 60 * 1000);
    }
}
return new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());
}

/**
* @param flag  true:返回上两周第一天， false：返回上两周最后一天
* 返回上两周的开始日期或结束日期
**/
public static String getFirstDateOfPre2Week(boolean flag){
Calendar cal = Calendar.getInstance();
//获取当前时间
long today = cal.getTimeInMillis();
//设定周一是每周的第一天
cal.setFirstDayOfWeek(Calendar.MONDAY);
//得到当天处在当周的第几天，周一是当周的第一天
int dayNum = cal.get(Calendar.DAY_OF_WEEK)-1;
// System.out.println(dayNum);

if(dayNum == 0){
if(flag){
cal.setTimeInMillis(today - (20 - dayNum) * 24 * 60 * 60 * 1000);
}else{
cal.setTimeInMillis(today - (14 - dayNum) * 24 * 60 * 60 * 1000);
}
}else if(dayNum >= 1 && dayNum < 7){
if(flag){
cal.setTimeInMillis(today - (dayNum - 1 + 14) * 24 * 60 * 60 * 1000);
    }else{
    cal.setTimeInMillis(today + (7 - dayNum - 14) * 24 * 60 * 60 * 1000);
    }
}
return new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());
}

/**
* 返回当前时间的年份
**/
public static int getYear(){
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
return cal.get(Calendar.YEAR);
}

/**
* 返回当前时间的月份
**/
public static int getMonth(){
Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
return cal.get(Calendar.MONTH);
}

/**
* 判断某个年份是否为闰年
* @return true是闰年，false不是闰年
**/
public static boolean isLeapYear(int yearparam){
boolean flag = false;  
if(yearparam%4 != 0){      
flag = false;  
}else if(yearparam%100 != 0){     
flag = true;  
}else if(yearparam%400 != 0){  
flag = false;     
}else{  
flag = true;  
}         
 
// if(flag == true){  
// System.out.println("是闰年");  
// }else{  
// System.out.println("不是闰年");  
// }

return flag;
}

public static boolean isLeapYear2(int yearparam){
Calendar calendar = Calendar.getInstance();  
boolean flag = ((GregorianCalendar)calendar).isLeapYear(yearparam);

// if(flag == true){  
// System.out.println("是闰年");  
// }else{  
// System.out.println("不是闰年");  
// }

return flag;
}

/**
* 返回当前年当前月份最大天数
**/
public static int getMaxDayOfCurMonth(){
Calendar cal = Calendar.getInstance();
    cal.set(Calendar.DATE, 1);  //把日期设置为当月第一天
    cal.roll(Calendar.DATE, -1);  //日期回滚一天，也就是最后一天
    int maxDate = cal.get(Calendar.DATE);
//    System.out.println("当月最大天数:" + maxDate);
    return maxDate;
}

/**
* 返回当前年上月份最大天数
**/
public static int getMaxDayOfPreMonth(){
//取得系统当前时间
    Calendar cal = Calendar.getInstance();
    //取得系统当前时间所在月第一天时间对象
    cal.set(Calendar.DAY_OF_MONTH, 1);
    //日期减一,取得上月最后一天时间对象
    cal.add(Calendar.DAY_OF_MONTH, -1);
    //输出上月最后一天日期
//    System.out.println("上月最大天数：" + cal.get(Calendar.DAY_OF_MONTH));
    int maxDate = cal.get(Calendar.DAY_OF_MONTH);
    return maxDate;
}

/**
* 返回某年某月最大天数
**/
public static int getMaxDayOfMonth(int yearparam, int monthparam){
int[] daysInMonth = new int[]{31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};  //平年每月天数
if(isLeapYear2(yearparam)){  //判断是否为闰年
if(monthparam == 2){
return 29;
    }
}

return daysInMonth[monthparam - 1];
}

// public static void main(String[] args) {
//
// }
}