Take a look at http://tomcat.apache.org/tomcat-6.0-doc/class-loader-howto.html. Then consider that tomcat's database pooling is instantiated in tomcat's internal classes which do not have access to any webapp's WEB-INF/lib folder. The driver has to be visible to both tomcat's internal classes and the individual webapps, so it's best placed in tomcat's lib folder (or common/lib for older versions of tomcat).
--David Martin Gainty wrote: > very thorough analysis > > hopefully quick question on location of mysql libraries > > > > Tomcat managed database connections: > > Requires the MySQL connectors to be in $CATALINA_HOME/lib > > > Hibernate managed database connections: > > Based on the above, you'll need to place the MySQL connection jar in > your WEB-INF/lib directory. > > > any reason why Tomcat managed DB connection would not read mysql jars located > in WEB-INF/lib? > > > > thanks again > Martin Gainty > ______________________________________________ > Verzicht und Vertraulichkeitanmerkung/Note de déni et de confidentialité > > Diese Nachricht ist vertraulich. Sollten Sie nicht der vorgesehene Empfaenger > sein, so bitten wir hoeflich um eine Mitteilung. Jede unbefugte Weiterleitung > oder Fertigung einer Kopie ist unzulaessig. Diese Nachricht dient lediglich > dem Austausch von Informationen und entfaltet keine rechtliche > Bindungswirkung. Aufgrund der leichten Manipulierbarkeit von E-Mails koennen > wir keine Haftung fuer den Inhalt uebernehmen. > > Ce message est confidentiel et peut être privilégié. Si vous n'êtes pas le > destinataire prévu, nous te demandons avec bonté que pour satisfaire informez > l'expéditeur. N'importe quelle diffusion non autorisée ou la copie de ceci > est interdite. Ce message sert à l'information seulement et n'aura pas > n'importe quel effet légalement obligatoire. Étant donné que les email > peuvent facilement être sujets à la manipulation, nous ne pouvons accepter > aucune responsabilité pour le contenu fourni. > > > > > > >> Date: Mon, 20 Jul 2009 19:56:32 -0700 >> From: its_toas...@yahoo.com >> Subject: Re: Seeking the right solution to java.lang.ClassNotFoundException: >> com.mysql.jdbc.Driver >> To: users@tomcat.apache.org >> >> >> --- On Mon, 7/20/09, David Smith <d...@cornell.edu> wrote: >> >> >>> From: David Smith <d...@cornell.edu> >>> Subject: Re: Seeking the right solution to >>> java.lang.ClassNotFoundException: com.mysql.jdbc.Driver >>> To: "Tomcat Users List" <users@tomcat.apache.org> >>> Date: Monday, July 20, 2009, 6:16 PM >>> Caldarale, Charles R wrote: >>> >>>>> From: David Smith [mailto:d...@cornell.edu] >>>>> Subject: Re: Seeking the right solution to >>>>> java.lang.ClassNotFoundException: >>>>> >>> com.mysql.jdbc.Driver >>> >>>>> This configuration is using a tomcat managed >>>>> >>> database pool. Put your >>> >>>>> mysql jar file in tomcat's lib folder and you'll >>>>> >>> see the error go away. >>> >>>>> >>>>> >>>> But the stated intent is to use C3P0 pooling, rather >>>> >>> than Tomcat's pooling; in that case, the <Resource> >>> element must be removed and instead configured via whatever >>> mechanism C3P0 wants. Can't have both. >>> >>>> - Chuck >>>> >>>> >>>> >>>> >>> No argument here. I'm just diagnosing the current >>> issue. If the OP >>> wants help with C3PO, that should be the configuration we >>> are given. >>> >>> --David >>> >> Late to the thread, and this is probably overkill. >> >> This is my understanding concerning how the Tomcat / Hibernate / database >> environment works. Your mileage may vary, and I will probably be corrected >> by some people on the list. >> >> Please note that I've only used Tomcat managed database pooling. >> >> Tomcat Managed Database Pooling >> =============================== >> >> Anyway, here is my environment. >> >> OS - Fedora 10 >> =================== >> jdk/jre - 1.6.0_14 >> Tomcat - 6.0.20 >> MySQL - 5.0.77-1 >> IDE - NetBeans 6.7 >> Hibernate - 3.2.5.ga (provided with NetBeans) >> >> OS - Windows/XP Professional SP 3 >> =================== >> jdk/jre - 1.6.0_14 >> Tomcat - 6.0.20 >> MySQL - 5.1.31 >> IDE - NetBeans 6.7 >> Hibernate - 3.2.5.ga (provided with NetBeans) >> >> I've chosen to use Tomcat's database pooling for the NetBeans DVD Store >> tutorial sample application. This necessitates several changes in how the >> application is configured. >> >> Basics >> ====== >> >> 1. Per Tomcat documentation, I've placed >> mysql-connector-java-5.0.8-bin.jar in Tomcat's lib directory. This >> makes it available to Tomcat in order to set up database pooling >> >> 2. All Hibernate jars are located in WEB-INF/lib. NetBeans builds the >> war file correctly, so I don't have to copy any jar files around. >> >> Web Application >> =============== >> >> This also follows the Tomcat documentation for creating Tomcat-managed >> connection pooling. >> >> 1. In META-INF/context.xml: >> >> <?xml version="1.0" encoding="UTF-8"?> >> <Context antiJARLocking="true" path="/DVDStore"> >> <Resource auth="Container" >> driverClassName="com.mysql.jdbc.Driver" >> maxActive="30" maxIdle="10" >> maxWait="10000" name="jdbc/sakila" >> password="*****" >> type="javax.sql.DataSource" >> url="jdbc:mysql://localhost/sakila" >> username="*****"/> >> </Context> >> >> Obviously, replace the asterisks with the appropriate username and >> password. Replace the database url with your appropriate database. >> >> 2. In WEB-INF/web.xml: >> >> <resource-ref> >> <description>This is a MySQL database connection</description> >> <res-ref-name>jdbc/sakila</res-ref-name> >> <res-type>javax.sql.DataSource</res-type> >> <res-auth>Container</res-auth> >> </resource-ref> >> >> Hibernate Configuration >> ======================= >> >> So far, this has all been more or less boilerplate Tomcat >> configuration. The next step is to get Hibernate to talk to Tomcat's >> database connection pool as opposed to its own connection pool or a >> direct connection. >> >> After searching a bit on the Internet, I found that the following >> connection information works. >> >> 1. In hibernate.cfg.xml located in WEB-INF/: >> >> <!-- using container-managed JNDI --> >> <propertyname="hibernate.connection.datasource"> >> java:comp/env/jdbc/sakila >> </property> >> >> Note that jdbc/sakila matches the web.xml resource-ref-name, which >> matches the name attribute in context.xml. java:comp/env/ is the >> namespace to look up the jdbc reference. >> >> No other connection or pooling information should be present in your >> hibernate.cfg.xml file. >> >> Application Code >> >> ================ >> >> Since Hibernate hides a lot of the details for connection management, >> this code should not have to change. In particular: >> >> 1. Creating the SessionFactory >> >> // SessionFactory from standard hibernate.cfg.xml file >> >> try { >> sessionFactory = >> new AnnotationConfiguration().configure().buildSessionFactory(); >> } catch (Throwable ex) { >> // Log the exception. >> log.fatal("Initial SessionFactory creation failed.", ex); >> throw new ExceptionInInitializerError(ex); >> } >> >> 2. Getting the SessionFactory >> >> public static SessionFactory getSessionFactory() { >> return sessionFactory; >> } >> >> For my application, both of these code snippets live in >> HibernateUtil.java. My code also creates an mbean for monitoring >> Hibernate. >> >> You can then wrap this code up in a servlet context listener, which >> should then create the session factory (which connects to the Tomcat - >> provided connection pool) at application startup. It's also handy for >> cleaning up resources when the application is shut down. In my case, >> I use this to unregister the monitoring mbean. >> >> Other Notes >> =========== >> >> If you look at your logs, you may see the following warning: >> >> INFO SessionFactoryObjectFactory:82 - >> Not binding factory to JNDI, no JNDI name configured >> >> This is due to the fact that Hibernate can bind a session factory to a >> JNDI name, but none is configured. This is not the JDBC resource. >> This facility probably exists to make sharing session factories >> easier, and to clean up calls like the following: >> >> Session session = HibernateUtil.getSessionFactory().openSession(); >> >> Tomcat provides a read-only InitialContext, while Hibernate requires >> read-write. Tomcat is apparently following the specification for >> unmanaged containers. If you want to bind the session factory to a >> JNDI object, you'll either have to move to a managed server >> (Glassfish, JBoss, etc.), or search on the Internet for some posted >> work-arounds. >> >> The recommendation from the Hibernate documentation is to just leave >> out the hibernate.session_factory_name property when working with >> Tomcat to not try binding to JNDI. >> >> >> Hibernate Managed Database Pooling >> ================================== >> >> I've not tried this, since I always rely on container managed database >> connections. However, after reading the documentation, I gather that >> this is what needs to be done. >> >> Web Application Configuration >> ============================= >> >> 1. Remove the <Resource></Resource> element from the context.xml >> file. Tomcat is not going to be managing the database connection. >> >> 2. Remove the <resource-ref></resource-ref> element the web.xml file. >> Tomcat is not going to be managing the database connection. >> >> Jar Files >> ========= >> >> According to the Tomcat classloader documentation, Tomcat makes jar >> files available to your application in the following order: >> >> * Bootstrap classes of your JVM >> * System class loader classses (described above) >> * /WEB-INF/classes of your web application >> * /WEB-INF/lib/*.jar of your web application >> * $CATALINA_HOME/lib >> * $CATALINA_HOME/lib/*.jar >> >> In particular, the following two pieces of information should be >> noted. >> >> 1. The jar files in lib/ are made available to both your application >> and to Tomcat. Database connection jars are placed here if you >> will be relying on Tomcat to manage connection pooling. >> >> 2. In general, application-specific jars (such as Hibernate's >> connection pooling jars) should NOT be placed in the lib/ directory >> of Tomcat. >> >> Based on the above, you'll need to place the MySQL connection jar in >> your WEB-INF/lib directory. Hibernate ships with the CP30 connection >> pooling classes, so as long as the Hibernate jars are in your >> WEB-INF/lib directory (which they should be), you'll be fine. >> >> Hibernate Application Configuration >> =================================== >> >> Since Hibernate will be managing both the connection and the database >> pooling, you'll have to configure Hibernate with that information. >> >> In hibernate.cfg.xml, you'll need both connection information and >> connection pooling information. Here are the snippets of that file >> >> <!-- connection information --> >> <property name="hibernate.connection.driver_class"> >> com.mysql.jdbc.Driver >> </property> >> <property name="hibernate.connection.url"> >> jdbc:mysql://localhost/sakila >> </property> >> <property name="hibernate.connection.username">******</property> >> <property name="hibernate.connection.password">******</property> >> >> <!-- database pooling information --> >> <property name="connection_provider_class"> >> org.hibernate.connection.CP30ConnectionProvider >> </property> >> <property name="c3p0.minPoolSize"> >> 5 >> </property> >> <property name="c3p0.timeout"> >> 1000 >> </property> >> >> There are probably other properties to configure, but that should get >> things up and running. As always, change the database properties to >> reflect your particular application. >> >> Summary >> ======= >> >> Tomcat managed database connections: >> >> 1. Requires META-INF/context.xml information >> 2. Requires WEB-INF/web.xml information >> 3. Requires a simple JNDI configuration referencing the connection >> 4. Requires the MySQL connectors to be in $CATALINA_HOME/lib >> 5. Requires the Hibernate jars to be in WEB-INF/lib >> >> Hibernate managed database connections: >> >> 1. Requires NO META-INF/context.xml information >> 2. Requires NO WEB-INF/web.xml information >> 3. Requires connection information to be in hibernate.cfg.xml >> 4. Requires pooling information to be in hibernate.cfg.xml >> 5. Requires MySQL connectors to be in WEB-INF/lib (ideally) >> 6. Requires the Hibernate jars to be in WEB-INF/lib >> >> Hope this helps. >> >> /mde/ >> >> PS - I just hacked together the Hibernate-controlled database connection / >> pooling on a freshly installed Tomcat 6.0.20. It works as advertised. >> >> --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
