时间工具类

package com.ljl.test;

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

/**
 * 日期处理
 */
public class DateUtils {

    public static SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    public static String dateToStr(Date date){
        return sdf.format(date);
    }
    public static Date strToDate(String time){
        try {
            return sdf.parse(time);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }

    //获取当天的开始时间
    public static Date getDayBegin() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
//        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTime();
    }
    //获取当天的结束时间
    public static Date getDayEnd() {
        Calendar cal = new GregorianCalendar();
        cal.set(Calendar.HOUR_OF_DAY, 23);
        cal.set(Calendar.MINUTE, 59);
        cal.set(Calendar.SECOND, 59);
        return cal.getTime();
    }
    //获取昨天的开始时间
    public static Date getBeginDayOfYesterday() {
        Calendar cal = new GregorianCalendar();
        cal.setTime(getDayBegin());
        cal.add(Calendar.DAY_OF_MONTH, -1);
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        return cal.getTime();
    }
    //获取昨天的结束时间
    public static Date getEndDayOfYesterDay() {
        Calendar cal = new GregorianCalendar();
        cal.setTime(getDayEnd());
        cal.add(Calendar.DAY_OF_MONTH, -1);
        cal.set(Calendar.HOUR_OF_DAY, 23);
        cal.set(Calendar.MINUTE, 59);
        cal.set(Calendar.SECOND, 59);
        return cal.getTime();
    }
    //获取本周的开始时间
    @SuppressWarnings("unused")
    public static Date getBeginDayOfWeek() {
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date());
        int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
        if (dayofweek == 1) {
            dayofweek += 7;
        }
        cal.add(Calendar.DATE, 2 - dayofweek);
        return getDayStartTime(cal.getTime());
    }
    //获取本周的结束时间
    public static Date getEndDayOfWeek(){
        Calendar cal = Calendar.getInstance();
        cal.setTime(getBeginDayOfWeek());
        cal.add(Calendar.DAY_OF_WEEK, 6);
        Date weekEndSta = cal.getTime();
        return getDayEndTime(weekEndSta);
    }
    //获取上周的开始时间
    @SuppressWarnings("unused")
    public static Date getBeginDayOfLastWeek() {
        Date date = new Date();
        if (date == null) {
            return null;
        }
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
        if (dayofweek == 1) {
            dayofweek += 7;
        }
        cal.add(Calendar.DATE, 2 - dayofweek - 7);
        return getDayStartTime(cal.getTime());
    }
    //获取上周的结束时间
    public static Date getEndDayOfLastWeek(){
        Calendar cal = Calendar.getInstance();
        cal.setTime(getBeginDayOfLastWeek());
        cal.add(Calendar.DAY_OF_WEEK, 6);
        Date weekEndSta = cal.getTime();
        return getDayEndTime(weekEndSta);
    }
    //获取本月的开始时间
    public static Date getBeginDayOfMonth() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 1, 1);
        return getDayStartTime(calendar.getTime());
    }
    //获取本月的结束时间
    public static Date getEndDayOfMonth() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 1, 1);
        int day = calendar.getActualMaximum(5);
        calendar.set(getNowYear(), getNowMonth() - 1, day);
        return getDayEndTime(calendar.getTime());
    }
    //获取上月的开始时间
    public static Date getBeginDayOfLastMonth() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 2, 1);
        return getDayStartTime(calendar.getTime());
    }
    //获取上月的结束时间
    public static Date getEndDayOfLastMonth() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(getNowYear(), getNowMonth() - 2, 1);
        int day = calendar.getActualMaximum(5);
        calendar.set(getNowYear(), getNowMonth() - 2, day);
        return getDayEndTime(calendar.getTime());
    }
    //获取某个日期的开始时间
    public static Timestamp getDayStartTime(Date d) {
        Calendar calendar = Calendar.getInstance();
        if(null != d) calendar.setTime(d);
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),    calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return new Timestamp(calendar.getTimeInMillis());
    }
    //获取某个日期的结束时间
    public static Timestamp getDayEndTime(Date d) {
        Calendar calendar = Calendar.getInstance();
        if(null != d) calendar.setTime(d);
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),    calendar.get(Calendar.DAY_OF_MONTH), 23, 59, 59);
        calendar.set(Calendar.MILLISECOND, 999);
        return new Timestamp(calendar.getTimeInMillis());
    }
    //获取今年是哪一年
    public static Integer getNowYear() {
        Date date = new Date();
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(date);
        return Integer.valueOf(gc.get(1));
    }
    //获取本月是哪一月
    public static int getNowMonth() {
        Date date = new Date();
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(date);
        return gc.get(2) + 1;
    }

    public static void main(String[] args) throws Exception {
        //测试
        System.out.println(dateToStr(getDayBegin()));
        System.out.println(dateToStr(getDayEnd()));

        System.out.println(dateToStr(getBeginDayOfYesterday()));
        System.out.println(dateToStr(getEndDayOfYesterDay()));

        System.out.println(getBeginDayOfLastWeek());
        System.out.println(getEndDayOfLastWeek());

        System.out.println(getBeginDayOfWeek());
        System.out.println(getEndDayOfWeek());

        System.out.println(getBeginDayOfLastMonth());
        System.out.println(getEndDayOfLastMonth());

        System.out.println(getBeginDayOfMonth());
        System.out.println(getEndDayOfMonth());
    }
}