Liu Haoyu / vehicle-simple

  package com.objecteye.utils;
  
  import com.alibaba.fastjson.JSONArray;
  import com.objecteye.entity.PageResult;
  
  import java.text.SimpleDateFormat;
  import java.util.ArrayList;
  import java.util.Date;
  import java.util.List;
  
  public class UserTools {
  
      public static JSONArray getJSONArrayByList(List list) {
          JSONArray jsonArray = new JSONArray();
          if (list == null || list.isEmpty()) {
              return jsonArray;
          }
          jsonArray.addAll(list);
          return jsonArray;
      }
  
      public static String nowToDate() {
          SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
          return sdf.format(new Date());
      }
  
      /**
       * 统一手动分页
       *
       * @param baseList    原始数据集合

       * @param currentPage 页码
       * @param pageVolume  页面容量

       * @return 结果集
       */

      public static PageResult makePageResultByBaseList(List baseList, int currentPage, int pageVolume) {
          return new PageResult<>(getPageTotalByBaseList(baseList, pageVolume),
                  getPagedResultByBaseList(baseList, currentPage, pageVolume));
      }
  
      /**
       * 手动分页获取页码数量
       *
       * @param baseList   原始数据集合
       * @param pageVolume 页面容量
       * @return 页数
       */
      public static int getPageTotalByBaseList(List baseList, int pageVolume) {
          return getPageTotalByBaseList(baseList.size(), pageVolume);
      }
  
      /**
       * 手动分页获取页码数量
       *
       * @param size       集合数量
       * @param pageVolume 页面容量
       * @return 页数
       */
      public static int getPageTotalByBaseList(int size, int pageVolume) {
          return (size / pageVolume) + ((size % pageVolume > 0) ? 1 : 0);
      }

      /**
       * 手动获取分页对应页面的数据
       *
       * @param baseList    原始数据集合
       * @param currentPage 页码
       * @param pageVolume  页面容量
       * @return 数据集合
       */
      public static List getPagedResultByBaseList(List baseList, int currentPage, int pageVolume) {
          int pageTotal = getPageTotalByBaseList(baseList, pageVolume);
          int fromIndex = (currentPage - 1) * pageVolume;

          int toIndex;

          if (currentPage == pageTotal) {

              toIndex = baseList.size();
          } else if (pageTotal == 0) {

              return new ArrayList<>();

          } else {

              toIndex = currentPage * pageVolume;

              if (toIndex > baseList.size()) {
                  toIndex = baseList.size();
              }
              if (fromIndex >= toIndex) {

                  return new ArrayList<>();

              }
          }

          return baseList.subList(fromIndex, toIndex);

      }
  }