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  • J2EE操作Oracle的clob类型字段

    1.插入和更新

    插入一条数据,注意CLOB字段,需要先插入一个空的clob类型 empty_clob(),然后再单独更新clob字段

    在插入到更新之间一定要将自动提交设为false,否则,再次查找时就不能正确更新,查找时一定要用select XXX from table where ... for update   
    如果不加for   update会报:“row containing the LOB value is not locked”;
    如果在插入前没有将自动提交设为false会报  “fetch out of sequence”。

    String sql = "insert into User_CourseWare(User_Id,Courseware_Id,Progress,Report ,id)values( ?,?,?,empty_clob(),  user_courseware_sq.nextval  )";
      conn.setAutoCommit(false);//设置不自动提交   PreparedStatement pstmt
    = conn.prepareStatement(sql); pstmt.setInt(1, userid); pstmt.setInt(2, courseware_Id); pstmt.setInt(3, Progress); pstmt.executeUpdate(); conn.commit(); pstmt = null; ResultSet rs = null; CLOB clob = null; String sql1 = "select Report from User_CourseWare where User_Id=? and Courseware_Id=? for update"; pstmt = conn.prepareStatement(sql1); pstmt.setInt(1, userid); pstmt.setInt(2, courseware_Id); rs = pstmt.executeQuery(); if (rs.next()) { clob = (CLOB) rs.getClob(1); } Writer writer = clob.getCharacterOutputStream(); writer.write(CourseClob); writer.flush(); writer.close(); conn.commit();

    2.查询

    Clob clob = rs.getClob("MODULE_INFO");
    方法一:
    byte[] info = clob!=null?clob.getSubString((long)1,(int)clob.length()).getBytes():null;
    方法二:
    String line = "";
    String value = "";
    Reader reader = clob.getCharacterStream();
    BufferedReader br = new BufferedReader(reader);
    while ((line = br.readLine()) != null) {
        value += line + "\r\n";
    }
        System.out.println(value);
    byte[] info = value.getBytes();
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  • 原文地址:https://www.cnblogs.com/johnason/p/3026529.html
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