Closing InputStream Too Early on setCharacterStream()

JDBC for SQL Server - Herong's Tutorial Examples

∟SQL Server CLOB (Character Large Object) - TEXT

∟Closing InputStream Too Early on setCharacterStream()

This section describes an error condition where executeUpdate() gives an exception if the Reader is closed too early.

The program in the previous tutorial worked nicely. But if you make a mistake by placing the bodyIn.close() statement before ps.executeUpdate(), you will get an IOException when ps.executeUpdate() is called. The reason is simple, reading of data from the Reader is done at the time of executeUpdate() call, not before. Here is a test program:

/* SqlServerClobSetCharacterStreamError.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class SqlServerClobSetCharacterStreamError {
  public static void main(String [] args) {
    Connection con = null;
    try {
      com.microsoft.sqlserver.jdbc.SQLServerDataSource ds
        = new com.microsoft.sqlserver.jdbc.SQLServerDataSource();
      ds.setServerName("localhost");
//      ds.setPortNumber(60782);
      ds.setInstanceName("SQLEXPRESS");
      ds.setDatabaseName("AdventureWorks2019");
      ds.setUser("Herong");
      ds.setPassword("T0pSecret");
      con = ds.getConnection();

// Deleting the record for re-testing
      String subject = "Test of setCharacterStream() methods";
      Statement sta = con.createStatement();
      sta.executeUpdate("DELETE FROM Article WHERE Subject = '"
        +subject+"'");

// Inserting CLOB value with a PreparedStatement
      PreparedStatement ps = con.prepareStatement(
        "INSERT INTO Article (Subject, Body) VALUES (?,?)");
      ps.setString(1, subject);
      Reader bodyIn =
        new FileReader("SqlServerClobSetCharacterStream.java");
      File fileIn = new File("SqlServerClobSetCharacterStream.java");
      ps.setCharacterStream(2, bodyIn, (int) fileIn.length());

// Error - Closing the Reader too early.
      bodyIn.close();

      int count = ps.executeUpdate();
      ps.close();

// Retrieving CLOB value with getString()
      sta = con.createStatement();
      ResultSet res = sta.executeQuery("SELECT * FROM Article"
        +" WHERE Subject = '"+subject+"'");
      res.next();
      System.out.println("The inserted record: ");
      System.out.println("   Subject = "+res.getString("Subject"));
      System.out.println("   Body = "
        +res.getString("Body").substring(0,256));
      res.close();

      sta.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

The IOException with newer versions of JDK is shown below. The message tells me that the Reader is closed.

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar \
  SqlServerClobSetCharacterStreamError

com.microsoft.sqlserver.jdbc.SQLServerException:
An error occurred while reading the value from the stream object.
Error: "java.io.IOException: Stream closed"
  at com.microsoft.sqlserver.jdbc.TDSWriter.error(IOBuffer.java:3576)
  at com.microsoft.sqlserver.jdbc.TDSWriter.writeReader(IOBuffer.ja...
  at com.microsoft.sqlserver.jdbc.TDSWriter.writeRPCReaderUnicode(I...
  at com.microsoft.sqlserver.jdbc.DTV$SendByRPCOp.execute(dtv.java:...
  at com.microsoft.sqlserver.jdbc.DTV.executeOp(dtv.java:1464)
  at com.microsoft.sqlserver.jdbc.DTV.sendByRPC(dtv.java:1503)
  ...

However, with JDK 1.6, the error message doesn't tell me that the Reader is closed.

herong> Progra~1\java\jdk1.6.0_02\bin\java \
   -cp .;sqljdbc.jar SqlServerClobSetCharacterStreamError

com.microsoft.sqlserver.jdbc.SQLServerException:
  Unexpected IOException processing character stream Reader.
  at com.microsoft.sqlserver.jdbc.SQLServerException
    .makeFromDriverError(...)
  at com.microsoft.sqlserver.jdbc.IOBuffer
    .bufferAppendRPCReader(...)
  at com.microsoft.sqlserver.jdbc.DTV$SendByRPCOp.execute(...)
  at com.microsoft.sqlserver.jdbc.DTV.executeOp(Unknown Source)
  at com.microsoft.sqlserver.jdbc.DTV.sendByRPC(Unknown Source)
  at com.microsoft.sqlserver.jdbc.Parameter.sendByRPC(...)