Connection conn = DriverManager.getConnection(
                            url,
                            username, pwd);

       String sqlInsert = "insert into tbl_clob (id,my_clob) values(?,?)";

       PreparedStatement stmt = connect.prepareStatement(sqlInsert);

       stmt.setLong( 1 , 1 );

       CLOB newClob = oracle.sql.CLOB.createTemporary(connect, false, 
               oracle.sql.CLOB.DURATION_SESSION);

       String str ="qwerty"; // эту строку занесем в CLOB

       newClob.open(CLOB.MODE_READWRITE);
       Writer tempClobWriter = newClob.getCharacterOutputStream();
       tempClobWriter.write(str);
       tempClobWriter.flush();
       tempClobWriter.close();
       
       newClob.close();
       stmt.setClob( 2 ,newClob);

        int  rowcnt = stmt.executeUpdate();

       newClob.freeTemporary();
       newClob =  null ;
       connect.commit();