DateUtil

package com.controller.util;

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

public class DateUtil {
    
    public static Date parseStr(String formatDate,String date) throws ParseException{
        if(StringUtil.isNull(date))return null;
        return new SimpleDateFormat(formatDate).parse(date);
    }
    
    public static String formatDate(String formatDate,Date date) throws ParseException{
        if(StringUtil.isNull(date))return "";
        return new SimpleDateFormat(formatDate).format(date);
    }
    
    public static String parseStr(String formatStr,String formatDate,String date) throws ParseException{
        return new SimpleDateFormat(formatDate).format(new SimpleDateFormat(formatStr).parse(date));
    }
    
    public static Long diffDate(Date d1,Date d2){
        return (d2.getTime()-d1.getTime())/1000;
    }
    
    public static int getMonthDay(int year, int month) {
        int result = 0;
        switch (month) {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            result = 31;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            result = 30;
            break;
        case 2:
            result = 28;
            if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
                result = 29;
            }
            break;
        }

        return result;
    }

    public static int getMonthDays(int year, int month) {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, year);
        cal.set(Calendar.MONTH, month - 1);

        return cal.getActualMaximum(Calendar.DATE);
    }
    //获取年份
    public static int getyear(Date year){
        Calendar cld = Calendar.getInstance();
        Date date = year;
        cld.setTime(date);
        cld.get(Calendar.YEAR);
        return  cld.get(Calendar.YEAR);
    }
    
    public static String defFormatDate(Date date) throws ParseException{
        return new SimpleDateFormat("yyyy-MM-dd").format(date);
    }
    
    /**
     * 获得两个日期的相差月数
     * */
    public static int getMonth(Date start, Date end) {
        if(null==start || null==end){
            return 0 ;
        }
        if (start.after(end)) {
            Date t = start;
            start = end;
            end = t;
        }
        Calendar startCalendar = Calendar.getInstance();
        startCalendar.setTime(start);
        Calendar endCalendar = Calendar.getInstance();
        endCalendar.setTime(end);
        Calendar temp = Calendar.getInstance();
        temp.setTime(end);
        temp.add(Calendar.DATE, 1);
 
        int year = endCalendar.get(Calendar.YEAR) - startCalendar.get(Calendar.YEAR);
        int month = endCalendar.get(Calendar.MONTH) - startCalendar.get(Calendar.MONTH);
 
        if ((startCalendar.get(Calendar.DATE) == 1)&& (temp.get(Calendar.DATE) == 1)) {
            return year * 12 + month + 1;
        } else if ((startCalendar.get(Calendar.DATE) != 1) && (temp.get(Calendar.DATE) == 1)) {
            return year * 12 + month;
        } else if ((startCalendar.get(Calendar.DATE) == 1) && (temp.get(Calendar.DATE) != 1)) {
            return year * 12 + month;
        } else {
            return (year * 12 + month - 1) < 0 ? 0 : (year * 12 + month);
        }
    }
 
    public static Date firstDay( Date date) throws ParseException{
        if(StringUtil.isNull(date))return null;
        Calendar calaf = Calendar.getInstance();
        //设置当月为最后一天
        calaf.setTime(date); 
        calaf.set(Calendar.DAY_OF_MONTH , 1);
        date = calaf.getTime();
        return date;
    }
    
    ////获取当前月最后一天
    public static Date lastDay( Date date) throws ParseException{
        if(StringUtil.isNull(date))return null;
        
        Calendar calast = Calendar.getInstance();
        calast.setTime(date); 
        calast.set(Calendar.DAY_OF_MONTH, calast.getActualMaximum(Calendar.DAY_OF_MONTH));
        date = calast.getTime();
        System.out.println("当月最后一天:"+date);
        return date; 
    }
    
}