Error in setting up a datasource in Tomcat 6.0's JNDI

[Vidya Moorthy]

Hi
I am a struts newbie and was trying to access a MySQL 5.1 database from the struts application for a login registration tutorial. After reading a tutorial from Tomcat 6.0 documentation for setting up a datasource in JNDI, I created a test table in the DB and tried to access it from a jsp according to the tutorial. It works fine but when I try to access it from an action, I get an exception message like this

org.apache.struts.action.RequestProcessor processException
WARNING: Unhandled Exception thrown: class java.lang.ClassCastException
Mar 20, 2008 2:48:49 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet action threw exception
java.lang.ClassCastException: org.apache.tomcat.dbcp.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
at com.yourcompany.struts.action.TestAction.execute(TestAction.java:58)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:584)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Unknown Source)
This is the code which I used in the action. According to the MVC, DAO should be done from a model is what I infer. But I just wanted to try it from an action for test purposes

 
package com.yourcompany.struts.action;
 
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
 
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
 
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
 
import com.mysql.jdbc.Connection;
 
 
public class TestAction extends Action {

 

public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) throws NamingException, SQLException {

try{

Context initContext = new InitialContext();
Context envContext  = (Context)initContext.lookup("java:/comp/env");

DataSource ds = (DataSource)envContext.lookup("jdbc/TestDB");
********The below line throws the exception*******
Connection conn = (Connection) ds.getConnection();
Statement statement = conn.createStatement();
ResultSet rs =
statement.executeQuery("Select * from testdata");
String id = rs.getString(1);
System.out.println(id);
}
catch(NamingException ne){
System.out.println("There was a naming exception" +ne.getMessage());
}
catch(SQLException s){
System.out.println(s.getMessage());
}
return mapping.findForward("success");
}
}
I added this in the web.xml file along with my other information
 <resource-ref>
      <description>DB Connection</description>
      <res-ref-name>jdbc/TestDB</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
  </resource-ref>
 and this in the context.xml file of Tomcat 6.0
<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
               maxActive="100" maxIdle="30" maxWait="10000"
               username="root" password="abcd1234" driverClassName="com.mysql.jdbc.Driver"
               url="jdbc:mysql://localhost:3306/strutsdatabase?autoReconnect=true"/>
 
 
   

Please help me with this!
Thanks in advance
Vidya

[ March 20, 2008: Message edited by: Vidya Moorthy ]

[ March 20, 2008: Message edited by: Vidya Moorthy ]
[ March 20, 2008: Message edited by: Vidya Moorthy ]

[Joe Ess]

You don't need this explicit cast because getConnection is declared to return Connection implementation:

Connection conn = (Connection) ds.getConnection();    

I'm at a loss as to why that cast would throw a ClassCastException, however.

[Vidya Moorthy]

Joe
That was it. I changed the line to
java.sql.Connection conn = ds.getConnection();
based on your suggestion and it worked. Wow, I have been stuck at this for almost 2 days now. Thanks a ton!
Vidya