简书链接:坑爹奇葩的jdbcgetColumnNameindex竟然从1开始
文章字数：205,阅读全文大约需要1分钟
我做了一个jdbc底层项目，jdbc底层实际上是http请求。 

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/**
 * Get the designated column's name.
 *
 * @param column the first column is 1, the second is 2, ...
 * @return column name
 * @exception SQLException if a database access error occurs
 */
String getColumnName(int column) throws SQLException;

/**
 * Get the designated column's table's schema.
 *
 * @param column the first column is 1, the second is 2, ...
 * @return schema name or "" if not applicable
 * @exception SQLException if a database access error occurs
 */
String getSchemaName(int column) throws SQLException;

实现

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/**
 * Return the column descriptor given a column index.
 *
 * @param column The column index (from 1 .. n).
 * @return The column descriptor as a <code>ColInfo<code>.
 * @throws SQLException
 */
ColInfo getColumn(int column) throws SQLException {
    if (column < 1 || column > columnCount) {
        throw new SQLException(
                Messages.get("error.resultset.colindex",
                        Integer.toString(column)), "07009");
    }

    return columns[column - 1];
}


我本来是写的从1开始的，后面写webapi我自己都纳闷，额，我怎么给写成1了，怎么这么低级的错误，我就把哪个地方改成了0 ，把<=count 改成count,然后切换为jdbc模式的时候出错了，坑爹，坑爹，必须记录下来，搞得我改过来改过去

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while (resultSet.next()) {
          ResultSetMetaData rsMetaData = resultSet.getMetaData();
          //检索列名列表
          LinkedHashMap<String, Object> hashMap = new LinkedHashMap<>();
          int count = rsMetaData.getColumnCount();
          keymaploop:
          for (int i = 1; i <= count; i++) {// getColumn 从1 开始
              String columnName = rsMetaData.getColumnName(i);
              int columnType = rsMetaData.getColumnType(i);
              Object object = null;
              if (columnType == Types.VARBINARY) {
                  object = resultSet.getBinaryStream(columnName);
              } else if (columnType == Types.CLOB) {
                  Clob clob = resultSet.getClob(columnName);
                  object = ClobToString(clob);
              } else if (columnType == Types.BLOB) {
                  Blob blob = resultSet.getBlob(columnName);
                  if (blob != null) {
                      object = blob.getBinaryStream();
                  }
              } else {
                  object = resultSet.getObject(columnName);
              }
              if (onlyOneColumn) {
                  String result = String.valueOf(object == null ? "" : object);
                  if (!TextUtils.isEmpty(result)) {
                      list.add(result);
                  }
                  break keymaploop;//只查询一列作为list
              } else {
                  if (object instanceof InputStream) {
                      hashMap.put(columnName, new JDBCWrapper.InputStreamWrap((InputStream) object, columnName));
                  } else if (object instanceof Array) {
                      hashMap.put(columnName, object);
                  } else {
                      hashMap.put(columnName, String.valueOf(object == null ? "" : object));
                  }

              }
          }
          if (!onlyOneColumn) {
              list.add(hashMap);//否则返回一个字符串list
          }


      }

除此之外，注册输出函数第一个index=1是返回值，也是从1开始的，就问奇葩不奇葩。