Hi,
I'm attempting to integrate database connection pooling into an exisiting JSP-based web application.
I'm running Tomcat 5.5.2 Server, with J2SE 1.5.0 and a MySQL database (version 11.18) accessed through the com.mysql.jdbc package.
I've followed MySQL instructions from this page:
http://jakarta.apache.org/tomcat/tomcat-5.0-doc/jndi-datasource-examples-howto.html
I made the changes to server.xml and the web app's web.xml, changing variables to match the database name, user name and password of the correct database. I ensured the MySQL package was in common/lib/.
My DAO objects now have constructors of the following form, which was adapted from code found online ('broadband' is the database name):
private Connection myConn; private DataSource dataSource;
/**
* Constructs the data accessor using the connection pool
*
* @exception SQLException thrown for SQL errors
*/
public SearchDAO() throws SQLException { try { // retrieve datasource
Context init = new InitialContext();
Context ctx = (Context) init.lookup("java:comp/env");
dataSource = (DataSource) ctx.lookup("jdbc/broadband"); // get connection
synchronized (dataSource) {myConn = dataSource.getConnection();
}
} catch (NamingException ex) { System.err.println(
"new SearchDAO: Cannot retrieve java:comp/env/jdbc/broadband: "
+ ex); } catch (SQLException excep) { System.err.println(
"new SearchDAO: Could not get connection: " + excep); } catch (Exception e) { System.err.println("new SearchDAO: " + e); // System.out.println ("In the catch block : ....");
//e.printStackTrace();}
}
The constructor throws the following exception:
org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
The connect URL is present in server.xml and is correct for the database.
My only guess at this point is that the howto document above asks for the Context tag to be added to server.xml between the example close Context and the first open Host tag, however there wasn't an example Context tag in server.xml and there appears to be a context.xml file in the same directory. I'm wondering if Contexts have moved to a different file in a recent version of Tomcat? It's just a wild guess (and I've no idea how to add the Context to context.xml as there's already a Context tag in there and no higher level tag around it).
Any help would be greatly appreciated. Sorry if I'm wasting your time with an obvious or frequently asked question, I've googled and read quite a few documents, but I think I'm just at the 'stabbing in the dark' point and could do with guru guidance.
Thanks,
Nat.
-- Nat Titman Developer
MitchellConnerSearson 3-5 High Pavement The Lace Market Nottingham NG1 1HF Tel +44 (0)115 959 6455 Fax +44 (0)115 959 6456 Direct +44 (0)115 959 6462 www.choosemcs.co.uk
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