How to use Connection pool and DataSources with Tomcat ?

Tomcat allows you toconfigure DataSources for your J2EE web application in a context.xml file that is stored in your web application project.

1. Install the JDBC Driver

2. Install the .jar file(s) containing the JDBC driver in Tomcat's common/lib folder.

    You do not need to put them in your application's WEB-INF/lib folder.

    When working with J2EE DataSources, the web application server manages connections for your application.

3. Create META-INF/context.xml 

    In the root of your web app directory structure, create a folder named META-INF (all caps).

    Inside that folder, create a file named context.xml that contains a Resource like this :  

    (example: SQL server)   

    <?xml version="1.0" encoding="UTF-8"?>

    <Context>

       <Resource name="jdbc/myDB" auth="Container"
       type="javax.sql.DataSource" username="wally" password="wally"

      driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"

      url="jdbc:sqlserver://localhost;DatabaseName=mytest;

      SelectMethod=cursor;"  maxActive="8"  />

    </Context>

4. Access the data in a servlet : 

  InitialContext ic = new InitialContext();

  DataSource ds = (DataSource) ic.lookup("java:comp/env/jdbc/myDB");

  Connection c = ds.getConnection();

  ...

  c.close();

Note: when doing the DataSource lookup, you must prefix the JNDI name ofthe resource with java:comp/env/