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

 <!-- maxTotal: Maximum number of database connections in pool. Make sure 
  you configure your mysqld max_connections large enough to handle all of your 
  db connections. Set to -1 for no limit. -->

 <!-- maxIdle: Maximum number of idle database connections to retain in pool. 
  Set to -1 for no limit. See also the DBCP documentation on this and the minEvictableIdleTimeMillis 
  configuration parameter. -->

 <!-- maxWaitMillis: Maximum time to wait for a database connection to become 
  available in ms, in this example 10 seconds. An Exception is thrown if this 
  timeout is exceeded. Set to -1 to wait indefinitely. -->

 <!-- username and password: MySQL username and password for database connections -->

 <!-- driverClassName: Class name for the old mm.mysql JDBC driver is org.gjt.mm.mysql.Driver 
  - we recommend using Connector/J though. Class name for the official MySQL 
  Connector/J driver is com.mysql.jdbc.Driver. -->

 <!-- url: The JDBC connection url for connecting to your MySQL database. -->

 <Resource
  name="jdbc/memoapp_db"
  auth="Container"
  type="javax.sql.DataSource"
  maxTotal="100"
  maxIdle="30"
  maxWaitMillis="10000"
  username="memoapp"
  password="memoapp"
  driverClassName="com.mysql.jdbc.Driver"
  url="jdbc:mysql://localhost:3306/memoapp_db" />

</Context>

<?xml version="1.0" encoding="UTF-8"?>
<web-app
 xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
 version="2.4"
>
 <description>memo app</description>
 <resource-ref>
  <description>DB Connection</description>
  <res-ref-name>jdbc/memoapp_db</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
 </resource-ref>
</web-app>

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
 <display-name>Archetype Created Web Application</display-name>
 <servlet>
  <servlet-name>MemoAppMain</servlet-name>
  <display-name>MemoAppMain</display-name>
  <description></description>
  <servlet-class>jp.example.www.MemoAppMain</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>MemoAppMain</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>

 <resource-ref>
  <description>DB Connection</description>
  <res-ref-name>jdbc/memoapp_db</res-ref-name>
  <res-type>javax.sql.DataSource</res-type>
  <res-auth>Container</res-auth>
 </resource-ref>
</web-app>

         try {
             Class.forName("com.mysql.cj.jdbc.Driver");
-            con = DriverManager.getConnection(url, user, pass);
+            Context initContext = new InitialContext();
+            Context envContext  = (Context)initContext.lookup("java:/comp/env");
+            DataSource ds = (DataSource)envContext.lookup("jdbc/memoapp_db");
+            con = ds.getConnection();
+            System.out.println("con: " + con);
             smt = con.createStatement();