Tomcat 7.0 Connection pooling - jdbc driver exception

Question

I want to implement connection pooling on my Tomcat server. Here is my context.xml file (placed under WebContent/META-INF/context.xml:

<Context path="/evappserver" reloadable="true">
    <Resource
          name="jdbc/evapp"
          auth="Container"
          type="javax.sql.DataSource"
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          initialSize="34"
          maxActive="377"
          maxIdle="233"
          minIdle="89"
          timeBetweenEvictionRunsMillis="34000"
          minEvictableIdleTimeMillis="55000"
          validationQuery="SELECT 1"
          validationInterval="34"
          testOnBorrow="true"
          removeAbandoned="true"
          removeAbandonedTimeout="55"
          username="root"
          password=""
          driverClassName="com.mysql.jdbc.Driver"
          url="jdbc:mysql://localhost:3306/evapp?allowMultiQueries=true"
     />
</Context> 

I have a maven project so the mysql jdbc driver is imported via the pom.xml file, like this:

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.6</version>
</dependency>

Here is my java code which throws the exception:

    Context initContext  = new InitialContext();
    Context envContext  = (Context) initContext.lookup("java:/comp/env");
    dataSource = (DataSource) envContext.lookup("jdbc/evapp"); //here is the exception

Here is the exception:

May 13, 2014 10:39:58 AM org.apache.naming.NamingContext lookup
WARNING: Unexpected exception resolving reference
java.sql.SQLException: com.mysql.jdbc.Driver
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:254)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:182)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:702)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:634)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:488)
    at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:144)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:116)
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:103)
    at org.apache.tomcat.jdbc.pool.DataSourceFactory.createDataSource(DataSourceFactory.java:539)
    at org.apache.tomcat.jdbc.pool.DataSourceFactory.getObjectInstance(DataSourceFactory.java:237)
    at org.apache.naming.factory.ResourceFactory.getObjectInstance(ResourceFactory.java:143)
    at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:321)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:843)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:154)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:831)
    at org.apache.naming.NamingContext.lookup(NamingContext.java:168)
    at com.evappserver.dblayer.DBType.<init>(DBType.java:62)
    at com.evappserver.dblayer.MySqlDB.<init>(MySqlDB.java:16)
    at com.evappserver.logiclayer.BaseLogic.getMainDbConnection(BaseLogic.java:19)
    at com.evappserver.logiclayer.PasswordLoginLogic.doLogin(PasswordLoginLogic.java:27)
    at com.evappserver.servlets.PasswordLoginServlet.doGet(PasswordLoginServlet.java:37)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:266)
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:246)
    ... 38 more

Is there something wrong with this configuration?

Answer 1

I had this same problem. For a reason unknown to me, putting the mysql-connector-java*.jar in WEB-INF/lib no longer works in Ubuntu LTS 14.04

I solved it by copying this file (and this file alone) to /usr/share/tomcat7/lib and restarted tomcat7 as a service service tomcat7 restart and everything sprang to life.

Best of luck

Answer 2

check if the classpath of your project contains the file mysql-connector-java-5.1.6.jar. Did maven run without problems?

Answer 3

I think you should include the driver for MySQL in your tomcat /lib folder instead of deploying it along with your web application. This way the server will find the proper classes to instantiate your connection pool and everything should go fine.