<Context docBase="HelloWeb" path="/HelloWeb" reloadable="true" source="org.eclipse.jst.jee.server:HelloWeb">
      	<Resource name="jdbc/msg"
            auth="Container"
            type="javax.sql.DataSource"
            username="root"
            password="root"
            driverClassName="com.mysql.jdbc.Driver"
            url="jdbc:mysql://localhost:3306/test"
            maxActive="8"
            maxIdle="4"/>
      </Context>	

Connection conn = null;
		try {
			Context initCtx = new InitialContext();
			Context envCtx = (Context) initCtx.lookup("java:comp/env");
			DataSource ds = (DataSource)
			  envCtx.lookup("jdbc/test");
			 conn = ds.getConnection();
			//conn.close();
		} catch (NamingException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
		}