Java之~分页工具类

方法一：/**
   * 分页1
   */
   /**
   * @param sql
   * mysql原生sql语句
   * @param pageNo
   * 第几页
   * @param pageSize
   * 一页显示多少条
   * @param c
   * 返回的对象类型
   * @return
   */
   protected <K> Map<String, Object> getMapDataBySQl(String sql, Integer pageNo, int pageSize, Class<K> c) {
       if (pageNo == null || pageNo < 1)
           pageNo = 1;
       int index = getSQLSubIndex(sql);
       if (index == 0)
           return new HashMap<String, Object>();
       String countStr = sql.substring(index);
       countStr = "select count(*) " + countStr;
       // 获取总数
       long count = 0;
       try {
           count = Long.parseLong(getCurrentSession().createSQLQuery(countStr).list().get(0).toString());
       } catch (Exception e) {
           count = 0;
       }
       long pageCount = (count % pageSize == 0 ? count / pageSize : count / pageSize + 1);

       // 设置返回值
       Map<String, Object> result = new HashMap<String, Object>();
       sql += " limit " + (pageNo - 1) * pageSize + "," + pageSize;
       @SuppressWarnings("unchecked")
       List<K> dataProperty = getCurrentSession().createSQLQuery(sql).addEntity(c).list();

       result.put("pageCount", pageCount);
       result.put("totalSize", count);
       result.put("data", dataProperty);
       return result;
   }

   private int getSQLSubIndex(String sql) {
       int upperIndex = sql.indexOf("FROM", 0) == -1 ? 0 : sql.indexOf("FROM", 0);
       int lowerIndex = sql.indexOf("from", 0) == -1 ? 0 : sql.indexOf("from", 0);
       int index = 0;
       if (lowerIndex == 0)
           index = upperIndex;
       if (upperIndex == 0)
           index = lowerIndex;
       if (lowerIndex != 0 && upperIndex != 0)
           index = Math.min(lowerIndex, upperIndex);
       return index;
   }

方法二：

   protected Map<String, Object> getMapData(StringBuffer sql, Integer pageNo, int pageSize) {
       if (pageNo == null || pageNo < 1)
           pageNo = 1;

       // 获取总数
       long count = getRowsNew(sql.toString(), null, null);
       int pageCount = (int) (count % pageSize == 0 ? count / pageSize : count / pageSize + 1);

// 设置返回值
Map<String, Object> result = new HashMap<String, Object>();

List<T> dataProperty = findListPage(sql.toString(), null, (pageNo - 1) * pageSize, pageSize);

       if (dataProperty == null || dataProperty.size() == 0) {
           result.put("pageCount", pageCount);
           result.put("totalSize", count);
           result.put("data", dataProperty);
           return result;
       }

       result.put("pageCount", pageCount);
       result.put("totalSize", count);
       result.put("data", dataProperty);
       return result;
   }

//这是调用的底层的方法

public long getRowsNew(String query, Map<String, Object> params, Class<?> entityClass) {
       String queryString = "select count(*) ";
       if (query != null) {
           queryString = queryString + " " + query;
       }

       Query q = this.sessionFactory.getCurrentSession().createQuery(queryString);
       if (params != null) {
           q.setProperties(params);
       }

return (Long) q.list().get(0);
}

public List<T> findListPage(String hql, Map<String, Object> params, int first, int max) {
       Query query = this.sessionFactory.getCurrentSession().createQuery(hql);
       query.setProperties(params);
       query.setFirstResult(first);
       query.setMaxResults(max);
       return query.list();
   }

Java之~分页工具类

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