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From António Casqueiro <ac...@yahoo.co.uk>
Subject ClassCastException OraclePreparedStatement
Date Wed, 05 Jun 2002 17:07:53 GMT
Connection Pool configuration

<Context path="/NASApp" docBase="NASApp"
reloadable="true">
    
    <Resource name="jdbc/pool" auth="Container"
              type="javax.sql.DataSource"/>
    <ResourceParams name="jdbc/pool">
        <parameter>
            <name>user</name>
            <value>DES</value>
        </parameter>
        <parameter>
            <name>password</name>
            <value>DES</value>
        </parameter>
        <parameter>
            <name>driverClassName</name>
           
<value>oracle.jdbc.driver.OracleDriver</value>
        </parameter>
        <parameter>
            <name>driverName</name>
           
<value>jdbc:oracle:oci8:MyUser/MyPass@MyDatabase</value>
        </parameter>
    </ResourceParams>
    
</Context>
Server.xml



Jar with the driver

<TOMCAT>\common\lib\classes12.jar



Get a connection from the Connection Pool

// Obtain our environment naming context
javax.naming.Context initCtx = new InitialContext();
javax.naming.Context context = (Context)
initCtx.lookup("java:comp/env");
            
System.out.println("TRY CONNECT");
            javax.sql.DataSource ds =
(javax.sql.DataSource)context.lookup("jdbc/pool");
            connection = ds.getConnection();
System.out.println("CONNECTED");



Cast the PreparedStatement to OraclePreparedStatement

import oracle.jdbc.driver.OraclePreparedStatement;
(...)

                pstat =
connection.getJDBCPreparedStatement(query);
                pstat.setFetchSize(fetchSize);

                System.out.println( "pstat.getClass()"
+ pstat.getClass() );
                if(pstat instanceof
oracle.jdbc.driver.OraclePreparedStatement) {
                    System.out.println("Yes -
STATprepOracle");
                }
                else {
                    System.out.println("No -
STATprepOracle");

                    if(pstat instanceof
oracle.jdbc.driver.OracleStatement) {
                        System.out.println("Yes -
STAToracle");
                    }
                    if(pstat instanceof
java.sql.Statement) {
                        System.out.println("Yes -
STATsql");
                    }
                    if(pstat instanceof
java.sql.PreparedStatement) {
                        System.out.println("Yes -
STATprepSql");
                    }
                    
                    Class c = pstat.getClass();
                    System.out.println( "c.getName():
" + c.getName() );
                    System.out.println(
"c.getPackage(): " + c.getPackage() );
                    System.out.println(
"c.getClassLoader(): " + c.getClassLoader() );
                }
               
oracle.jdbc.driver.OraclePreparedStatement ostat =
null;
try {
                ostat =
(oracle.jdbc.driver.OraclePreparedStatement) pstat;
}
catch (Throwable e) {
    e.printStackTrace();
}



               
ostat.defineColumnType(CODIGOPERFIL_ROW,
Types.VARCHAR);
               
ostat.defineColumnType(TIPOERROCLO_ROW,
Types.VARCHAR);



Console output

TRY CONNECT
CONNECTED
pstat.getClass()class
oracle.jdbc.driver.OraclePreparedStatement
No - STATprepOracle
Yes - STATsql
Yes - STATprepSql
c.getName():
oracle.jdbc.driver.OraclePreparedStatement
c.getPackage(): package oracle.jdbc.driver
c.getClassLoader(): StandardClassLoader
  available:
    Extension[javax.mail, implementationVendor=Sun
Microsystems, Inc., implementationVendorId=com.sun,
implementationVersion=1.2, specificationVendor=Sun
Microsystems, Inc., specificationVersion=1.2]
  delegate: false
  repositories:
    file:D:\java\tomcat40\common\classes\
    file:D:\java\tomcat40\common\lib\activation.jar
    file:D:\java\tomcat40\common\lib\classes12.jar
    file:D:\java\tomcat40\common\lib\crimson.jar
    file:D:\java\tomcat40\common\lib\jaxp.jar
   
file:D:\java\tomcat40\common\lib\jdbc2_0-stdext.jar
    file:D:\java\tomcat40\common\lib\jta-spec1_0_1.jar
    file:D:\java\tomcat40\common\lib\ldap.jar
    file:D:\java\tomcat40\common\lib\mail.jar
    file:D:\java\tomcat40\common\lib\naming-common.jar
   
file:D:\java\tomcat40\common\lib\naming-resources.jar
    file:D:\java\tomcat40\common\lib\servlet.jar
    file:D:\java\tomcat40\common\lib\tyrex-0.9.7.0.jar
  required:
----------> Parent Classloader:
sun.misc.Launcher$AppClassLoader@71732b

java.lang.ClassCastException:
oracle.jdbc.driver.OraclePreparedStatement
 (...)
        at
org.apache.jasper.runtime.HttpJspBase.service(Unknown
Source)
        at
javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(Unknown
Source)
        at
org.apache.jasper.servlet.JspServlet.serviceJspFile(Unknown
Source)
        at
org.apache.jasper.servlet.JspServlet.service(Unknown
Source)
        at
javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
        at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Unknown
Source)
        at
org.apache.catalina.core.ApplicationFilterChain.doFilter(Unknown
Source)
        at
org.apache.catalina.core.StandardWrapperValve.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invokeNext(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invoke(Unknown
Source)
        at
org.apache.catalina.core.ContainerBase.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardContextValve.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invokeNext(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invoke(Unknown
Source)
        at
org.apache.catalina.core.ContainerBase.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardContext.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardHostValve.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invokeNext(Unknown
Source)
        at
org.apache.catalina.valves.AccessLogValve.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invokeNext(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invoke(Unknown
Source)
        at
org.apache.catalina.core.ContainerBase.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardEngineValve.invoke(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invokeNext(Unknown
Source)
        at
org.apache.catalina.core.StandardPipeline.invoke(Unknown
Source)
        at
org.apache.catalina.core.ContainerBase.invoke(Unknown
Source)
        at
org.apache.catalina.connector.http.HttpProcessor.process(Unknown
Source)
        at
org.apache.catalina.connector.http.HttpProcessor.run(Unknown
Source)
        at java.lang.Thread.run(Thread.java:484)


java.lang.NullPointerException

 - - - - - - - -
- - QUESTION  - -
 - - - - - - - -
I'm trying to configure a Connection Pool in Tomcat 4
to Oracle 8.1.7 database.
Everything works fine if I don't cast my
PreparedStatement to OraclePreparedStatement, to take
advantage of the "defineColumnType" method (this will
save 2 roundtrips to the RDBMS when executing the
query [that's what the documentation says]).

To figure out what class do I have, do the folowing:
> => System.out.println( "pstat.getClass()" +
pstat.getClass() );
and I get the output
=> pstat.getClass()class
oracle.jdbc.driver.OraclePreparedStatement
If I use JBuilder in debug and "Evaluate" the "pstat"
object I also see a
"oracle.jdbc.driver.OraclePreparedStatement", so
probably the
"oracle.jdbc.driver.OraclePreparedStatement" was
casted to "java.sql.PreparedStatement" right?

How can I fix it? Maybe it has something to do with
the "tyrex" connection pool. Is there another way to
create a connection pool to Oracle 8.1.7 in Tomcat?
How? Thanks


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