Thread: Tomcat - PostgreSQL - Cannot load JDBC driver class "null"

Hi Craig,

I've done a similar implementation, and can only offer what worked for
me:

1. I've used the convenience RPM's from jpackage.org, and made sure the
following jar files are in the <CATALINA_HOME>/commons/lib folder:
    a) pg73b1jdbc3.jar
    b) jndi.jar
    c) commons-dbcp.jar
    d) commons-pool.jar

2. The relevant context in the server.xml file is:

<Context path="/webapps/DBTest" docBase="DBTest" debug="0"
                reloadable="true" crossContext="true">

    <Resource name="jdbc/postgres" auth="Container"
        type="javax.sql.DataSource"/>

    <ResourceParams name="jdbc/postgres">
            <parameter>
                    <name>factory</name>
            <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
        </parameter>
            <parameter>
                  <name>driverClassName</name>
                  <value>org.postgresql.Driver</value>
            </parameter>
            <parameter>
                  <name>url</name>
            <value>jdbc:postgresql://127.0.0.1:5432/DBTest</value>
            </parameter>
            <parameter>
                  <name>username</name>
                  <value>username</value>
            </parameter>
            <parameter>
                  <name>password</name>
                  <value>password</value>
            </parameter>
            <parameter>
                  <name>maxActive</name>
                  <value>20</value>
            </parameter>
            <parameter>
                  <name>maxIdle</name>
                  <value>10</value>
            </parameter>
            <parameter>
                  <name>maxWait</name>
                  <value>-1</value>
            </parameter>
            <parameter>
                  <name>removeAbandoned</name>
                  <value>true</value>
            </parameter>
            <parameter>
                  <name>removeAbandonedTimeout</name>
                  <value>60</value>
            </parameter>
         </ResourceParams>
</Context>

3. The relevant entry in the <DBTest>/WEB-INF/web.xml file is:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app
    PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
    "http://java.sun.com/dtd/web-app_2_3.dtd">

    <web-app> 
  <description>DBTest</description>
  <resource-ref>
    <res-ref-name>jdbc/postgres</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>
</web-app>


4. I've referenced this resource in a jsp as follows:

Context ic = new InitialContext();
DataSource source =
(DataSource)ic.lookup("java:comp/env/jdbc/postgres");
Connection con = source.getConnection();


That's it. If I had to guess at the error, I would presume it being that
you did not specify the resource type as javax.sql.DataSource in your
server.xml file.

Hope this helps.

David

On Fri, 2003-09-26 at 18:29, CRAIG GOLBY wrote:
> Help, I am tearing my hair out.
>
> I am a newbie to Linux and Tomcat, and am therefore amazed that I have
> got as far as I have, that said I now seem to be stuck in front of a
> brick wall, with no ladder !!
>
> Tomcat 4.1.24 is running on ServerOne (Red Hat 9), it is currently
> serving out a couple of very basic JSP's and seems to be working quite
> well. ServerOne also has J2SDK 1.4.1_03 installed.  PostgreSQL 7.3 is
> running on ServerTwo (Red Hat 9).  Have also installed pgAdminIII on
> both a Windows Laptop and ServerTwo.  The Laptop version works fine,
> if a little unstable, so TCP/IP connectivity is working fine.
>
> Within PostgreSQL I have created a new Db called "PersonalDb", within
> the public Schema I have created a table called "testOne".  TestOne
> has three columns, Id, FieldOne and DateStamp, and there are currently
> 2 rows of data within the table
>
> Sample of code used is below, along with a list of the Jar files in
> common/lib.
>
> I have read through so many mailing lists now and tried so many things
> that I dont know what I have and havent done, am fairly sure that it
> is either a configuration issue or a missing file so will no doubt
> kick myself when I find out the answer.
>
> Any assistance would be greatly appreciated.
>
> Regards
>
>
> Craig
>
>
> *******************************************************
> Server XML :- Tomcat/conf
> *******************************************************
> <Context path="/DBTest"
>          docBase="DBTest"
>          debug="5"
>          reloadable="true"
>          crossContext="true">
>
> <Logger className="org.apache.catalina.logger.FileLogger"
>         prefix="localhost_DBTest_log." suffix=".txt"
>         timestamp="true"/>
>
> <Resource name="jdbc/PersonalDb"
>           type="javax.sql.DataSource"
>           auth="Container"/>
>
> <ResourceParams name="jdbc/PersonalDb">
>  <parameter>
>   <name>factory</name>
>   <value>org.apache.commons.dbcp.BasicDataSourceFactory</value>
>  </parameter>
>
>  <parameter>
>   <name>driverClassName</name>
>   <value>org.postgresql.Driver</value>
>  </parameter>
>
>  <parameter>
>   <name>url</name>
>   <value>jdbc:postgresql://ServerTwo:5432/PersonalDb</value>
>  </parameter>
>
>  <parameter>
>   <name>username</name>
>   <value>myUser</value>
>  </parameter>
>
>  <parameter>
>   <name>password</name>
>   <value>myPassword</value>
>  </parameter>
>
>  <parameter>
>   <name>maxActive</name>
>   <value>10</value>
>  </parameter>
>
>  <parameter>
>   <name>maxIdle</name>
>   <value>30</value>
>  </parameter>
>
>  <parameter>
>   <name>maxWait</name>
>   <value>10000</value>
>  </parameter>
>
> </ResourceParams>
> </Context>
>
> </Host>
> </Engine>
> </Service>
>
>
> *******************************************************
> Web XML  :-  Tomcat/webapps/root/WEB-INF
> *******************************************************
>   <description>PostgreSQL Test App</description>
>     <resource-ref>
>        <description>postgreSQL Datasource example</description>
>        <res-ref-name>jdbc/PersonalDb</res-ref-name>
>        <res-type>javax.sql.DataSource</res-type>
>        <res-auth>Container</res-auth>
>    </resource-ref>
>
>
>
> *******************************************************
> My Class File
> *******************************************************
>
>   public void init() {
>     try{
>       Context ctx = new InitialContext();
>       if(ctx == null )
>           throw new Exception("Boom - No Context");
>       status = "checking CTX";
>
>       DataSource ds =
> (DataSource)ctx.lookup("java:comp/env/jdbc/PersonalDb");
>       status = "Completing Lookup of CTX";
>
>       if (ds != null)
>         {
>          status = "Creating Connection";
>          Connection conn = ds.getConnection();   <----- FAILS HERE
>          status = "Created Connection";
>          if(conn != null)
>            {
>             foo = "Got Connection "+conn.toString();
>             Statement stmt = conn.createStatement();
>             ResultSet rst =
>                 stmt.executeQuery(
>                   "select Id, FieldOne, DateStamp from
> Public.testOne");
>             status = "Completing Select";
>             if(rst.next())
>             {
>                foo=rst.getString(2);
>                bar=rst.getInt(3);
>             }
>             status = "Looped through Resultset";
>             conn.close();
>            }
>         }
>       else {status = "Fell into Else";}
>     }catch(Exception e) {
>       e.printStackTrace();
>         status = status + ", now in exception block :-" +
> e.toString();
>
>     }
>  }
>
> *******************************************************
> Class Files in Tomcat/common/lib
> *******************************************************
> activation.jar
> ant.jar
> collections-2.1.jar
> commons-collections.jar
> commons-dbcp-1.0.jar
> commons-dbcp.jar
> commons-logging-api.jar
> commons-pool.jar
> jasper-compiler.jar
> jasper-runtime.jar
> jdbc2_0-stdext.jar
> jndi.jar
> jta.jar
> mail.jar
> naming-common.jar
> naming-factory.jar
> naming-resources.jar
> pg73jdbc3.jar
> pool-1.0.1.jar
> postgresql.jar    (Copy of  pg73jdbc3.jar)
> servlet.jar
>