java 如何讀取clob

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.sql.Clob;

public List<Map<String, Object>> queryForList() {
  List<Map<String, Object>> rowList = new ArrayList<Map<String, Object>>();
  String driver = "";
  String url = "";
  String username = "";
  String password = "";
  String sql = "";
  log.info("查詢sql條件：" + sql);
  try {
    // 加載驅(qū)動程序，此處運用隱式注冊驅(qū)動程序的方法
    Class.forName(driver);
    log.info("加載驅(qū)動成功！");
  } catch (ClassNotFoundException e) {
    log.error("加載驅(qū)動程序，此處運用隱式注冊驅(qū)動程序的方法出錯：" + e.getMessage());
    e.printStackTrace();
  }
  try {
    // 創(chuàng)建連接對象
    Connection con = DriverManager.getConnection(url, username, password);
    // 創(chuàng)建sql執(zhí)行對象
    Statement st = con.createStatement();
    // 執(zhí)行sql語句并返回結(jié)果集
    ResultSet rs = st.executeQuery(sql);
    // 獲得結(jié)果集結(jié)構(gòu)信息,元數(shù)據(jù)
    ResultSetMetaData rsmd = rs.getMetaData();
    // 獲得列數(shù)
    int columnCount = rsmd.getColumnCount();
    // 用于接收每行數(shù)據(jù)
    Map<String, Object> rowData = null;
    // clob類型
    Clob clob = null;
    // clob轉(zhuǎn)成String
    String clobString = "";
    while (rs.next()) {
      rowData = new HashMap<String, Object>();
      for (int i = 1; i <= columnCount; i++) {
        // 判斷數(shù)據(jù)類型是否為Clob
        if (rs.getObject(i) instanceof Clob) {// Clob轉(zhuǎn)String
          clob = (Clob) rs.getObject(i);
          clobString = clob.getSubString((long) 1, (int) clob.length());
          rowData.put(rsmd.getColumnName(i), clobString);
        } else {
          rowData.put(rsmd.getColumnName(i), rs.getObject(i));
        }

      }
      rowList.add(rowData);
    }

    // 關閉相關的對象
    if (rs != null) {
      rs.close();
    }
    if (st != null) {
      st.close();
    }
    if (con != null) {
      con.close();
    }
  } catch (SQLException e) {
    e.printStackTrace();
  }
  return rowList;
}