jsl-questionnaire-base/src/main/java/com/qs/serve/common/util/PageUtil.java

package com.qs.serve.common.util;

import com.baomidou.mybatisplus.core.metadata.OrderItem;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.github.pagehelper.PageHelper;
import com.qs.serve.common.framework.exception.BusinessException;
import lombok.experimental.UtilityClass;
import org.springframework.util.StringUtils;

import java.util.ArrayList;
import java.util.List;

/**
 * 翻页工具类
 * @Author YenHex
 * @Date 2021/6/9
 * @Version: 1.0
 **/
@UtilityClass
public class PageUtil {

    private static final String PAGE_NUM = "pageNum";
    private static final String PAGE_SIZE = "pageSize";

    private static final String ORDER_TYPE = "orderType";
    private static final String ORDER_PROP = "orderProp";

    private static final String ORDER_TYPE_ASC = "ASC";
    private static final String ORDER_TYPE_DESC = "DESC";

    private static final int MAX_PAGE_SIZE = 66;

    public static <T> Page<T> getMbpPage(){
        Integer pageNum = getPageNum();
        Integer pageSize = getPageSize();
        String orderProp = getOrderProp();
        String orderType = getOrderType();
        if ( pageNum ==null || pageNum<1 || pageSize==null || pageSize<1) {
            throw new BusinessException("翻页参数异常",500);
        }
        Page<T> page = new Page<>();
        page.setCurrent(pageNum);
        page.setSize(pageSize);
        if(StringUtils.hasText(orderProp)){
            OrderItem orderItem = new OrderItem();
            orderItem.setColumn(orderProp);
            orderItem.setAsc(orderType.equals(ORDER_TYPE_ASC));
            List<OrderItem> orderItems = new ArrayList<>();
            orderItems.add(orderItem);
            page.setOrders(orderItems);
        }
        return page;
    }

    public static Integer getPageNum(){
        Integer pageNum=null;
        String pageNumStr = ServletUtils.getParameter(PAGE_NUM);
        if(StringUtils.hasText(pageNumStr)){
            pageNum = Integer.parseInt(pageNumStr);
        }
        return pageNum;
    }

    public static Integer getPageSize(){
        String pageSizeStr = ServletUtils.getParameter(PAGE_SIZE);
        Integer pageSize = null;
        if(StringUtils.hasText(pageSizeStr)){
            pageSize = Integer.parseInt(pageSizeStr);
        }
        if(pageSize!=null && pageSize > MAX_PAGE_SIZE){
            throw new BusinessException("超出数据额度",500);
        }
        return pageSize;
    }

    public static String getOrderProp(){
        String orderProp = ServletUtils.getParameter(ORDER_PROP);
        if(StringUtils.hasText(orderProp)){
            orderProp = orderProp.trim();
            if(orderProp.contains(".")){
                String[] strings = orderProp.split("\\.");
                return strings[0]+"."+strings[1];
            }
            return WordUtil.toLine(orderProp);
        }
        return null;
    }

    public static String getOrderType(){
        String orderType = ServletUtils.getParameter(ORDER_TYPE);
        if(StringUtils.hasText(orderType)){
            if(orderType.equalsIgnoreCase(ORDER_TYPE_DESC)){
                return ORDER_TYPE_DESC;
            }
        }
        return ORDER_TYPE_ASC;
    }

    public static Integer getStartRow(){
        Integer pageNum = getPageNum();
        Integer pageSize = getPageSize();
        if (pageNum==null || pageSize==null) {
            throw new BusinessException("翻页参数异常",500);
        }
        return (pageNum-1)*pageSize;
    }

    /**
     * 启动翻页（翻页失败，会抛出异常）
     * @return 是否使用翻页
     */
    public static boolean startPage(){
        return startPage(true);
    }

    /**
     *
     * @param throwEx 是否抛异常
     * @return 是否使用翻页
     */
    public static boolean startPage(boolean throwEx){
        return startPage(null,null,throwEx);
    }

    /**
     * 执行翻页
     * @param object POJO
     * @return 是否使用翻页
     */
    public static <T> boolean startPage(T object){
        return startPage(object,null,true);
    }

    public static <T> boolean startPage(String prefix){
        return startPage(null,prefix,true);
    }
    /**
     *
     * @param throwEx 是否抛异常
     * @return 是否使用翻页
     */
    public static <T> boolean startPage(T object,String prefix,boolean throwEx){
        Integer pageNum = getPageNum();
        Integer pageSize = getPageSize();
        String orderProp = getOrderProp();
        String orderType = getOrderType();
        if (pageNum!=null && pageNum>0 && pageSize!=null && pageSize>0) {
            if(!StringUtils.isEmpty(orderProp)){
                if(prefix==null && object!=null){
                    prefix = WordUtil.toLine(object.getClass().getSimpleName());
                }
                if(prefix!=null){
                    PageHelper.startPage(pageNum, pageSize).setOrderBy(prefix+"."+orderProp+" "+orderType);
                }else {
                    PageHelper.startPage(pageNum, pageSize).setOrderBy(orderProp+" "+orderType);
                }
                return true;
            }
            PageHelper.startPage(pageNum, pageSize);
            return true;
        }else{
            if(throwEx){
                throw new BusinessException("翻页参数异常",500);
            }
            return false;
        }
    }

}