It looks like a ClassLoader issue. Casting the same class loaded by two
different CLs causes a ClassCastException. Have you got the jar
containing org.enhydra.jdbc.pool.StandardXAPoolDataSource in more than
one place?

http://jakarta.apache.org/tomcat/tomcat-4.1-doc/class-loader-howto.html

HTH,

Jon

Marc Dugger wrote:
> I have a situation where I am attempting to downcast a DataSource resource
> into the exact class that getClass().getName() reports the object is, but
> it's causing a ClassCastException.
>
> --> server.xml:
>
> <GlobalNamingResources>
>    <Resource name="LoanAuditorDB" auth="Container"
> type="org.enhydra.jdbc.pool.StandardXAPoolDataSource"/>
>    <ResourceParams name="LoanAuditorDB">
> ...more
>  </ResourceParams>
> </GlobalNamingResources>
> ...more
> <Context path="/workbench"
> docBase="C:\Code\loanauditor\src\webapp\workbench"
>
> workDir="C:\Code\loanauditor\src\webapp\workbench\WEB-INF\work"
> reloadable="true" debug="0">
>         <ResourceLink name="jdbc/loanauditor"
>                  global="LoanAuditorDB"
>
> type="org.enhydra.jdbc.pool.StandardXAPoolDataSource"/>
>         <ResourceLink name="jta/loanauditor"
>                  global="UserTransaction"
>                  type="javax.transaction.UserTransaction"/>
>      </Context>
>
>
> --> web.xml
>
> <resource-ref>
>      <description>DB Connection</description>
>      <res-ref-name>jdbc/loanauditor</res-ref-name>
>      <res-type>org.enhydra.jdbc.pool.StandardXAPoolDataSource</res-type>
>      <res-auth>Container</res-auth>
>   </resource-ref>
>
> --> constructor from abstract class, AbstractDAO.java:
>
> protected AbstractDAO() {
>      try {
>         Context ctx = new InitialContext();
>         Object o = ctx.lookup("java:comp/env/jdbc/loanauditor");
>         log.debug("loanauditor from JNDI: " + o.getClass().getName());
>         ds = (org.enhydra.jdbc.pool.StandardXAPoolDataSource) o;
>         ds.setJdbcTestStmt("SELECT 1");
>      } catch (NamingException ne) {
>         log.fatal(ne.getMessage(), ne);
>         throw new RuntimeException(ne);
>      }
>   }
>
> --> logging:
>
> 2003-12-04 05:25:39,157 [main] DEBUG
> com.socotech.loanauditor.dao.AbstractDAO - loanauditor from JNDI:
> org.enhydra.jdbc.pool.StandardXAPoolDataSource
>
> --> stacktrace:
>
> java.lang.ClassCastException
>  at com.socotech.loanauditor.dao.AbstractDAO.<init>(AbstractDAO.java:31)
>  at
> com.socotech.loanauditor.dao.TorqueDomainTypeDAO.<init>(TorqueDomainTypeDAO.
> java:34)
>  at
> com.socotech.loanauditor.dao.TorqueDomainTypeDAO.getInstance(TorqueDomainTyp
> eDAO.java:29)
>  at
> com.socotech.loanauditor.dao.DAOFactory.getDomainTypeDAO(DAOFactory.java:79)
>  at
> com.socotech.loanauditor.web.listener.DomainTypeLoader.contextInitialized(Do
> mainTypeLoader.java:32)
>  at
> org.apache.catalina.core.StandardContext.listenerStart (StandardContext.java:
> 3271)
>  at
> org.apache.catalina.core.StandardContext.start (StandardContext.java:3613)
>  at org.apache.catalina.core.ContainerBase.start (ContainerBase.java:1188)
>  at org.apache.catalina.core.StandardHost.start (StandardHost.java:754)
>  at org.apache.catalina.core.ContainerBase.start (ContainerBase.java:1188)
>  at org.apache.catalina.core.StandardEngine.start (StandardEngine.java:363)
>  at org.apache.catalina.core.StandardService.start (StandardService.java:497)
>  at org.apache.catalina.core.StandardServer.start (StandardServer.java:2190)
>  at org.apache.catalina.startup.Catalina.start (Catalina.java:512)
>  at org.apache.catalina.startup.Catalina.execute (Catalina.java:400)
>  at org.apache.catalina.startup.Catalina.process (Catalina.java:180)
>  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>  at
> sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:39
> )
>  at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl
> .java:25)
>  at java.lang.reflect.Method.invoke (Method.java:324)
>  at org.apache.catalina.startup.Bootstrap.main (Bootstrap.java:203)
>
>
> Thanks in advance for any insight.
>
>
>
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