Problem using CLOB in JDBC (NewLOBAPISample)

Question

I've just tried to run the JDBC NewLOBAPISample, and everything works fine until I try to insert or update on the CLOB column using any characters other than base ASCII. For example, if I attempt to insert the String "$100", it works just fine, but "£100" results in:
java.sql.SQLException: No more data to read from socket
I've experimented with this issue with a much smaller test case of my own, and I've been able to narrow down the problem, as I've outlined below. In all cases, PreparedStatement is used for executing.
Let's say we have a table named "Test" with one CLOB column named "text".
The original "official" API for inserting a CLOB using the latest 1.4 JDBC Oracle thin driver is:
// first insert an "empty CLOB"
PreparedStatement ps;
ps = con.prepareStatement("INSERT INTO Test (text) VALUES (empty_clob())");
ps.executeUpdate();
// then select the empty CLOB
con.setAutoCommit(false);
ps = con.prepareStatement("SELECT text FROM Test FOR UPDATE");
ResultSet rs = ps.executeQuery();
rs.next();
CLOB clob = ((OracleResultSet)rs).getCLOB(1);
// now write to the CLOB
Writer out = clob.getCharacterOutputStream();
out.write(myLongText);
out.close();
// we're done
connection.commit();
The method that is advertised in NewLOBAPISample, and which I've also seen on the Java Developer Forum, is outlined here:
// first, create statement to insert
PreparedStatement ps;
ps = con.prepareStatement("INSERT INTO Test (text) VALUES (?)");
// create a temporary CLOB and write to it
CLOB clob = CLOB.createTemporary(con, true, CLOB.DURATION_SESSION);
Writer out = clob.getCharacterOutputStream();
out.write(myLongText);
// set the CLOB on the PreparedStatement and execute
ps.setClob(1, clob);
ps.executeUpdate();
Now, in the above two cases, if "myLongText" has any characters in it besides standard alpha-numerics, the latter approach will fail, although the former (original) approach will still work. In my case, I need to save Danish characters in the CLOB data. (I can't type these characters in this message, as for some reason they are being converted to "æ å ø" during posting, instead of the letters I've typed on my keyboard.)
Here is a stack trace when I try the createTemporary approach with a short String that contains one or more non-standard characters:
java.io.IOException: No more data to read from socket
     at oracle.jdbc.dbaccess.DBError.SQLToIOException(DBError.java:716)
     at oracle.jdbc.driver.OracleClobWriter.flushBuffer(OracleClobWriter.java:270)
     at oracle.jdbc.driver.OracleClobWriter.close(OracleClobWriter.java:232)
Here's the strack trace when the insert String contains only ONE character that is non-standard:
java.sql.SQLException: No more data to read from socket
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
     at oracle.jdbc.dbaccess.DBError.check_error(DBError.java:1160)
     at oracle.jdbc.ttc7.MAREngine.unmarshalUB1(MAREngine.java:963)
     at oracle.jdbc.ttc7.MAREngine.unmarshalSB1(MAREngine.java:893)
     at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:369)
     at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1891)
     at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1093)
     at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2047)
     at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:1940)
     at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2709)
     at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:589)
Any help with this would be MUCH appreciated.
Thanks,
David Karlton

Answer 1

hi David,
i tried inserting non-alphanumeric chars but still it goes thru fine.
here is what i did,
create table testlob ( id number(5),lobcol clob);
LobInJava.java
import java.sql.*;
import oracle.jdbc.*;
import oracle.sql.*;
class LobInJava
public static void main(String args[]) throws Exception
DriverManager.registerDriver(new
oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection
("jdbc:oracle:thin:@host:1522:ora9idb", "scott", "tiger");
StringBuffer myLongText = new StringBuffer("nm{H$ñVmZ".length() * 10 );
for(int i=0 ;i < 1000 ;i++ )
myLongText.append("nm{H$ñVmZ");
System.out.println( myLongText.length());
PreparedStatement ps;
ps = conn.prepareStatement("INSERT INTO Testlob (id,lobcol) VALUES (2,empty_clob())");
ps.executeUpdate();
// then select the empty CLOB
conn.setAutoCommit(false);
ps = conn.prepareStatement("SELECT lobcol FROM Testlob where id=2 FOR UPDATE");
ResultSet rs = ps.executeQuery();
rs.next();
CLOB clob = ((OracleResultSet)rs).getCLOB(1);
// now write to the CLOB
java.io.Writer out = clob.getCharacterOutputStream();
out.write(myLongText.toString());
out.close();
// we're done
conn.commit();
ps.close();
// first, create statement to insert
PreparedStatement ps;
ps = conn.prepareStatement("INSERT INTO Testlob (id,lobcol) VALUES (1,?)");
// create a temporary CLOB and write to it
CLOB clob = CLOB.createTemporary(conn, true, CLOB.DURATION_SESSION);
java.io.Writer out = clob.getCharacterOutputStream();
out.write(myLongText.toString());
out.close();
// set the CLOB on the PreparedStatement and execute
ps.setClob(1, clob);
ps.executeUpdate();
ps.close();
conn.close();
i am using jdk 1.3 and Oracle9i v9.0.1
Regards
Elango.