Since we don’t want to use external classes or libraries to handle database connections for our web applications we should stick to what comes built-in with the container server – in my case Apache Tomcat 7 and MySQL database server.
To keep the database connection pooling and cleanup functionality on the server-side you can use the following approach:
1.) In your web-app’s META-INF/context.xml add
<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/some-project">
<Resource name="jdbc/your-db-resource"
auth="Container"
type="javax.sql.DataSource"
factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
testWhileIdle="true"
testOnBorrow="true"
testOnReturn="false"
validationQuery="SELECT 1"
validationInterval="30000"
timeBetweenEvictionRunsMillis="30000"
maxActive="100"
maxIdle="30"
maxWait="10000"
initialSize="10"
removeAbandonedTimeout="60"
removeAbandoned="true"
logAbandoned="true"
minEvictableIdleTimeMillis="30000"
jmxEnabled="true"
jdbcInterceptors="org.apache.tomcat.jdbc.pool.interceptor.ConnectionState;
org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer"
username="root"
password=""
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/your_db"/>
</Context>
2.) In your WEB-INF/web.xml add reference to JDNI resource from above:
<resource-ref>
<res-ref-name>jdbc/your-db-resource</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
Also make sure to put the corresponding mysql connector library jar into tomcat/lib folder so that you don’t you an exception like so:
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:699)
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:631)
at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:485)
at org.apache.tomcat.jdbc.pool.ConnectionPool.
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:304)
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 org.apache.catalina.core.NamingContextListener.addResource(NamingContextListener.java:1061)
at org.apache.catalina.core.NamingContextListener.createNamingContext(NamingContextListener.java:671)
at org.apache.catalina.core.NamingContextListener.lifecycleEvent(NamingContextListener.java:270)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:247)
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:246)
… 29 more
Oct 31, 2012 11:23:25 AM org.apache.catalina.core.NamingContextListener addResource
WARNING: Failed to register in JMX: javax.naming.NamingException: com.mysql.jdbc.Driver
Oct 31, 2012 11:23:25 AM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler [“http-bio-8086”]
Oct 31, 2012 11:23:25 AM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler [“ajp-bio-8009”]
Oct 31, 2012 11:23:25 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 794 ms
That’s it!
A sample connection wrapper class would be:
package at.kerstner;
import java.sql.Connection;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.sql.DataSource;
abstract class DBConnection {
public static Connection getConnection() {
Connection conn = null;
try {
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:/comp/env");
DataSource ds = (DataSource) envContext.lookup("jdbc/your-db-resource");
conn = ds.getConnection();
} catch (Exception e) {
System.err.println("Failed to get connection: " + e.getMessage());
}
return conn;
}
}
Also make sure to have a look at my other post concerning problems when loading the resource factory class.