oracle的clob字段写入与读取

lob字段基本分为clob和blob，分别存储大文本和二进制流(图片)内容，以下记录下代码，仅供自己查看

/**

 * 读取clob
 */
public String selectClob() {
    String content = "null";
    try {
        connection = DB14Util.getCon();
        connection.setAutoCommit(false);
        ResultSet rs = null;
        CLOB clob = null;
        String sql = "";
        sql = "select TRACK_SPOT from IOV_DATA_SAVING where C_DATA_NO ='2007100858' ";
        PreparedStatement pstmt = connection.prepareStatement(sql);
        rs = pstmt.executeQuery();
        if (rs.next()) {
            clob = (CLOB) rs.getClob(1);
            if (clob != null && clob.length() != 0) {
                content = clob.getSubString((long) 1, (int) clob.length());
            }
        }
        rs.close();
        connection.commit();
        pstmt.close();
        connection.close();
    } catch (SQLException e) {
        e.printStackTrace();
        content = "error";
    }
    System.out.println(content);
    return content;
}

/**
 * 修改clob
 */
public static void updateClob(Map<Long,String> tidValMap){
    connection = DB14Util.getCon();
    String car_saving_tb = "IOV_DATA_SAVING";
    try {
        connection.setAutoCommit(false);
        for (Long key : tidValMap.keySet()) {
            String updateSql = "update " + car_saving_tb + " set TRACK_SPOT = empty_clob() where C_DATA_NO = ? " ;
            PreparedStatement pstmt = connection.prepareStatement(updateSql);
            Writer outStream = null;
            String jsonStr = tidValMap.get(key);
            pstmt.setString(1, key.toString());
            pstmt.executeUpdate();
            connection.commit();
            String update = "select TRACK_SPOT from " + car_saving_tb + " where C_DATA_NO ='" + key + "' for update";
            pstmt = connection.prepareStatement(update);
            ResultSet rs = pstmt.executeQuery();
            if (rs.next()) {
                //得到java.sql.Clob对象后强制转换为oracle.sql.CLOB
                oracle.sql.CLOB clob = (oracle.sql.CLOB) rs.getClob("TRACK_SPOT");
                outStream = clob.getCharacterOutputStream();
                //data是传入的字符串，定义：String data
                char[] c = jsonStr.toCharArray();
                outStream.write(c, 0, c.length);
                outStream.flush();
                outStream.close();
            }
            rs.close();
            connection.commit();
            pstmt.close();
        }
    }catch (SQLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    OracleConnUtil.closeConn(connection);
}