content: package org.ruoyi.core.page;
  
  import cn.hutool.core.collection.CollUtil;
  import cn.hutool.core.util.ObjectUtil;
  import com.baomidou.mybatisplus.core.metadata.OrderItem;
  import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
  import com.fasterxml.jackson.annotation.JsonIgnore;
  import lombok.Data;
  import org.ruoyi.common.core.exception.ServiceException;
  import org.ruoyi.common.core.utils.StringUtils;
  import org.ruoyi.common.core.utils.sql.SqlUtil;
  
  import java.io.Serial;
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * 分页查询实体类
   *
   * @author Lion Li
   */
  @Data
  public class PageQuery implements Serializable {
  
      @Serial
      private static final long serialVersionUID = 1L;
  
      /**
       * 分页大小
       */
      private Integer pageSize;
  
      /**
       * 当前页数
       */
      private Integer pageNum;
  
      /**
       * 排序列
       */
      private String orderByColumn;
  
      /**
       * 排序的方向desc或者asc
       */
      private String isAsc;
  
      /**
       * 当前记录起始索引 默认值
       */
      public static final int DEFAULT_PAGE_NUM = 1;
  
      /**
       * 每页显示记录数 默认值 默认查全部
       */
      public static final int DEFAULT_PAGE_SIZE = Integer.MAX_VALUE;
  
      /**
       * 构建分页对象
       */
      public <T> Page<T> build() {
          Integer pageNum = ObjectUtil.defaultIfNull(getPageNum(), DEFAULT_PAGE_NUM);
          Integer pageSize = ObjectUtil.defaultIfNull(getPageSize(), DEFAULT_PAGE_SIZE);
          if (pageNum <= 0) {
              pageNum = DEFAULT_PAGE_NUM;
          }
          Page<T> page = new Page<>(pageNum, pageSize);
          List<OrderItem> orderItems = buildOrderItem();
          if (CollUtil.isNotEmpty(orderItems)) {
              page.addOrder(orderItems);
          }
          return page;
      }
  
      /**
       * 构建排序
       *
       * 支持的用法如下:
       * {isAsc:"asc",orderByColumn:"id"} order by id asc
       * {isAsc:"asc",orderByColumn:"id,createTime"} order by id asc,create_time asc
       * {isAsc:"desc",orderByColumn:"id,createTime"} order by id desc,create_time desc
       * {isAsc:"asc,desc",orderByColumn:"id,createTime"} order by id asc,create_time desc
       */
      private List<OrderItem> buildOrderItem() {
          if (StringUtils.isBlank(orderByColumn) || StringUtils.isBlank(isAsc)) {
              return null;
          }
          String orderBy = SqlUtil.escapeOrderBySql(orderByColumn);
          orderBy = StringUtils.toUnderScoreCase(orderBy);
  
          // 兼容前端排序类型
          isAsc = StringUtils.replaceEach(isAsc, new String[]{"ascending", "descending"}, new String[]{"asc", "desc"});
  
          String[] orderByArr = orderBy.split(StringUtils.SEPARATOR);
          String[] isAscArr = isAsc.split(StringUtils.SEPARATOR);
          if (isAscArr.length != 1 && isAscArr.length != orderByArr.length) {
              throw new ServiceException("排序参数有误");
          }
  
          List<OrderItem> list = new ArrayList<>();
          // 每个字段各自排序
          for (int i = 0; i < orderByArr.length; i++) {
              String orderByStr = orderByArr[i];
              String isAscStr = isAscArr.length == 1 ? isAscArr[0] : isAscArr[i];
              if ("asc".equals(isAscStr)) {
                  list.add(OrderItem.asc(orderByStr));
              } else if ("desc".equals(isAscStr)) {
                  list.add(OrderItem.desc(orderByStr));
              } else {
                  throw new ServiceException("排序参数有误");
              }
          }
          return list;
      }
  
      @JsonIgnore
      public Integer getFirstNum() {
          return (pageNum - 1) * pageSize;
      }
  
      public PageQuery(Integer pageSize, Integer pageNum) {
          this.pageSize = pageSize;
          this.pageNum = pageNum;
      }
  
  }
  