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When I try to write a clob from Oracle, I receive "java.lang.ClassCastException"
This error occurs only for CLOB Type and only if I try to connect to
Oracle using WebLogic Jdbc Driver/Oracle POOL.
I can write CLOB or any other data using direct JDBC
connection to ORacle with out any problem.
Note :
... = (OracleResultSet)rs).getCLOB(1);
statement cause problem.
please help me...
Thank you.
The problem is that you have to deal with Weblogic classes when you use a pool. We
have code for updating CLOB's that works for both a straight Oracle connection or a
Weblogic pool connection. Here it is:
Usage:
PreparedStatement stmt = con.prepareStatement("select clob_column from table");
ResultSet rs = stmt.executeQuery();
setCLOBFromString(rs.getClob(1), "New Value"); // or
setCLOBFromString(rs.getObject(1), "New Value");
// Update a CLOB in the database. Since Weblogic's CLOB API does not appear to
offer
// a way to TRIM a clob when an update makes the CLOB smaller, the remaining space
// is filled with blanks.
public static void setCLOBFromString(Object obj, String str) throws SQLException
{
try {
int old_length = new Long(((java.sql.Clob)obj).length()).intValue();
int new_length = str.length();
Syslog.debug(DBAgent.class, "The current CLOB length is " + old_length + ", the
new length = " + new_length );
Writer out = null;
if (obj instanceof oracle.sql.CLOB) {
out = ((oracle.sql.CLOB)obj).getCharacterOutputStream();
} else {
out = ((weblogic.jdbc.common.OracleClob)obj).getCharacterOutputStream();
}
out.write( str.toCharArray() );
// Pad the string with spaces if a previous version was larger then this version
for(int i = new_length; i < old_length; i++)
out.write( " " );
out.flush();
out.close();
// Cut off any extraneous length of the CLOB, if possible
if (obj instanceof oracle.sql.CLOB && new_length < old_length) {
((oracle.sql.CLOB)obj).trim(new_length);
}
} catch (IOException ex) {
throw new SQLException(ex.toString());
}
}
I think I noticed that Java 1.4 offers ways to update CLOBs via the java.sql.Clob
interface, so then our vendor-specific troubles might be over...
Good luck,
Joop Kaashoek
SeungRyul Park wrote:
[color=blue]
> When I try to write a clob from Oracle, I receive "java.lang.ClassCastException"
>
> This error occurs only for CLOB Type and only if I try to connect to
> Oracle using WebLogic Jdbc Driver/Oracle POOL.
>
> I can write CLOB or any other data using direct JDBC
> connection to ORacle with out any problem.
>
> Note :
>
> ... = (OracleResultSet)rs).getCLOB(1);
>
> statement cause problem.
>
> please help me...
>
> Thank you.
>[/color]
I've resolved this problem using java.sql.Clob. But when you want to write, you need to cast to OracleThinClob
for more info and examples: [url]http://www.dosideas.com/wiki/CLOB_de_Oracle_en_Weblogic[/url]
Try the in built programme in XP. Copy everything you want to burn and paste the same on the CD writer drive. Then use the option(under CD writing tasks) write these files to the CD.
[QUOTE=unix;593007]The problem is that you have to deal with Weblogic classes when you use a pool. We
have code for updating CLOB's that works for both a straight Oracle connection or a
Weblogic pool connection. Here it is:
Usage:
PreparedStatement stmt = con.prepareStatement("select clob_column from table");
ResultSet rs = stmt.executeQuery();
setCLOBFromString(rs.getClob(1), "New Value"); // or
setCLOBFromString(rs.getObject(1), "New Value");
// Update a CLOB in the database. Since Weblogic's CLOB API does not appear to
offer
// a way to TRIM a clob when an update makes the CLOB smaller, the remaining space
// is filled with blanks.
public static void setCLOBFromString(Object obj, String str) throws SQLException
{
try {
int old_length = new Long(((java.sql.Clob)obj).length()).intValue();
int new_length = str.length();
Syslog.debug(DBAgent.class, "The current CLOB length is " + old_length + ", the
new length = " + new_length );
Writer out = null;
if (obj instanceof oracle.sql.CLOB) {
out = ((oracle.sql.CLOB)obj).getCharacterOutputStream();
} else {
out = ((weblogic.jdbc.common.OracleClob)obj).getCharacterOutputStream();
}
out.write( str.toCharArray() );
// Pad the string with spaces if a previous version was larger then this version
for(int i = new_length; i < old_length; i++)
out.write( " " );
out.flush();
out.close();
// Cut off any extraneous length of the CLOB, if possible
if (obj instanceof oracle.sql.CLOB && new_length < old_length) {
((oracle.sql.CLOB)obj).trim(new_length);
}
} catch (IOException ex) {
throw new SQLException(ex.toString());
}
}
I think I noticed that Java 1.4 offers ways to update CLOBs via the java.sql.Clob
interface, so then our vendor-specific troubles might be over...
Good luck,
Joop Kaashoek
SeungRyul Park wrote:
[color=blue]
> When I try to write a clob from Oracle, I receive "java.lang.ClassCastException"
>
> This error occurs only for CLOB Type and only if I try to connect to
> Oracle using WebLogic Jdbc Driver/Oracle POOL.
>
> I can write CLOB or any other data using direct JDBC
> connection to ORacle with out any problem.
>
> Note :
>
> ... = (OracleResultSet)rs).getCLOB(1);
>
> statement cause problem.
>
> please help me...
>
> Thank you.
>[/color][/QUOTE]
Hi,
If we use new oracle jdbc drivers i.e. ojdbc5.jar then we don't have to take such effert to insert data into CLOB column and this also solves the class cast exception as well.
Link to get this jar is,
[url]http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/htdocs/jdbc_111060.html[/url]
Thanks,
Hemant
Thanks,
Hemant