Pagehelper不是特别好用。对list直接分页

Pagehelper只对

PageHelper.startPage(pageNum,pageSize);
这一句后面的一个查询起作用。
如果后面有两个查询，
则在

PageInfo pageInfo = new PageInfo<>(messages);
int total=pageInfo.size();
只能获取当前页的条数。而不是总数。

这个时候，pagehelper就不好用了。
只能对list直接分页。

package com.zfzn.cwyms.message.util;

import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
/*
 * 由于为了以后使用方便,所有方法的返回类型都设为了 java.util.Date 请在使用时根据自己的需要进行日期格式化处理,如:
 *
 * import java.text.SimpleDateFormat;SimpleDateFormat simpleDateFormat = new
 * SimpleDateFormat("yyyy-MM-dd HH:mm:ss");String todayBegin =
 * simpleDateFormat.format
 * (DateUtils.getDayBegin());System.out.println(todayBegin );//输出结果为2017-10-26
 * 00:00:00
 */
/**
 * 1)获取当天的开始时间 
 * 2)获取当天的结束时间 
 * 3)获取昨天的开始时间 
 * 4)获取昨天的结束时间 
 * 5)获取明天的开始时间 
 * 6)获取明天的结束时间 
 * 7)获取本周的开始时间 
 * 8)获取本周的结束时间 
 * 9)获取上周的开始时间 
 * 10)获取上周的结束时间 
 * 11)获取本月的开始时间 
 * 12)获取本月的结束时间 
 * 13)获取上月的开始时间 
 * 14)获取上月的结束时间 
 * 15)获取本年的开始时间 
 * 16)获取本年的结束时间 
 * 17)获取某个日期的开始时间 
 * 18)获取某个日期的结束时间 
 * 19)获取今年是哪一年 
 * 20)获取本月是哪一月 
 * 21)两个日期相减得到的天数 
 * 22)两个日期相减得到的毫秒数 
 * 23)获取两个日期中的最大日期 
 * 24)获取两个日期中的最小日期 
 * 25)返回某月该季度的第一个月 
 * 26)返回某个日期下几天的日期 
 * 27)返回某个日期前几天的日期 
 * 28)获取某年某月到某年某月按天的切片日期集合(间隔天数的集合) 
 * 29)获取某年某月按天切片日期集合(某个月间隔多少天的日期集合)
 */

/**
 * 日期工具类
 */
public class DatesUtil {
    // 获取当天的开始时间
    public static java.util.Date getDayBegin() {
        Calendar cal = new GregorianCalendar();
        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 java.util.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);
        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);
        return cal.getTime();
    }

    // 获取明天的开始时间
    public static Date getBeginDayOfTomorrow() {
        Calendar cal = new GregorianCalendar();
        cal.setTime(getDayBegin());
        cal.add(Calendar.DAY_OF_MONTH, 1);
        return cal.getTime();
    }

    // 获取明天的结束时间
    public static Date getEndDayOfTomorrow() {
        Calendar cal = new GregorianCalendar();
        cal.setTime(getDayEnd());
        cal.add(Calendar.DAY_OF_MONTH, 1);
        return cal.getTime();
    }

    // 获取本周的开始时间
    @SuppressWarnings("unused")
    public static Date getBeginDayOfWeek() {
        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);
        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());
    }

    // 获取本年的开始时间
    public static Date getBeginDayOfYear() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, getNowYear());
        cal.set(Calendar.MONTH, Calendar.JANUARY);
        cal.set(Calendar.DATE, 1);
        return getDayStartTime(cal.getTime());
    }

    // 获取本年的结束时间
    public static java.util.Date getEndDayOfYear() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.YEAR, getNowYear());
        cal.set(Calendar.MONTH, Calendar.DECEMBER);
        cal.set(Calendar.DATE, 31);
        return getDayEndTime(cal.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;
    }

    // 两个日期相减得到的天数
    public static int getDiffDays(Date beginDate, Date endDate) {
        if (beginDate == null || endDate == null) {
            throw new IllegalArgumentException("getDiffDays param is null!");
        }
        long diff = (endDate.getTime() - beginDate.getTime())
                / (1000 * 60 * 60 * 24);
        int days = new Long(diff).intValue();
        return days;
    }

    // 两个日期相减得到的毫秒数
    public static long dateDiff(Date beginDate, Date endDate) {
        long date1ms = beginDate.getTime();
        long date2ms = endDate.getTime();
        return date2ms - date1ms;
    }

    // 获取两个日期中的最大日期
    public static Date max(Date beginDate, Date endDate) {
        if (beginDate == null) {
            return endDate;
        }
        if (endDate == null) {
            return beginDate;
        }
        if (beginDate.after(endDate)) {
            return beginDate;
        }
        return endDate;
    }

    // 获取两个日期中的最小日期
    public static Date min(Date beginDate, Date endDate) {
        if (beginDate == null) {
            return endDate;
        }
        if (endDate == null) {
            return beginDate;
        }
        if (beginDate.after(endDate)) {
            return endDate;
        }
        return beginDate;
    }

    // 返回某月该季度的第一个月
    public static Date getFirstSeasonDate(Date date) {
        final int[] SEASON = {1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4};
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int sean = SEASON[cal.get(Calendar.MONTH)];
        cal.set(Calendar.MONTH, sean * 3 - 3);
        return cal.getTime();
    }

    // 返回某个日期下几天的日期
    public static Date getNextDay(Date date, int i) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        cal.set(Calendar.DATE, cal.get(Calendar.DATE) + i);
        return cal.getTime();
    }

    // 返回某个日期前几天的日期
    public static Date getFrontDay(Date date, int i) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        cal.set(Calendar.DATE, cal.get(Calendar.DATE) - i);
        return cal.getTime();
    }

    // 获取某年某月到某年某月按天的切片日期集合(间隔天数的集合)
    @SuppressWarnings({"rawtypes", "unchecked"})
    public static List getTimeList(int beginYear, int beginMonth, int endYear,
                                   int endMonth, int k) {
        List list = new ArrayList();
        if (beginYear == endYear) {
            for (int j = beginMonth; j <= endMonth; j++) {
                list.add(getTimeList(beginYear, j, k));
            }
        } else {
            {
                for (int j = beginMonth; j < 12; j++) {
                    list.add(getTimeList(beginYear, j, k));
                }
                for (int i = beginYear + 1; i < endYear; i++) {
                    for (int j = 0; j < 12; j++) {
                        list.add(getTimeList(i, j, k));
                    }
                }
                for (int j = 0; j <= endMonth; j++) {
                    list.add(getTimeList(endYear, j, k));
                }
            }
        }
        return list;
    }

    // 获取某年某月按天切片日期集合(某个月间隔多少天的日期集合)
    @SuppressWarnings({"unchecked", "rawtypes"})
    public static List getTimeList(int beginYear, int beginMonth, int k) {
        List list = new ArrayList();
        Calendar begincal = new GregorianCalendar(beginYear, beginMonth, 1);
        int max = begincal.getActualMaximum(Calendar.DATE);
        for (int i = 1; i < max; i = i + k) {
            list.add(begincal.getTime());
            begincal.add(Calendar.DATE, k);
        }
        begincal = new GregorianCalendar(beginYear, beginMonth, max);
        list.add(begincal.getTime());
        return list;
    }

}

这个类的使用方法：

ListPageUtil listPageUtil = new ListPageUtil(messages,pageNum, pageSize);
List pagedList = listPageUtil.getPagedList();

转载于:https://www.cnblogs.com/zhanying999666/p/10155131.html