JNDI configuration for Tomcat 9 with Oracle

In this article, I am going to place the required source code to get data from the table by using the JNDI configuration. Below are the environment details that I have configured currently.
  • Windows - 7
  • Oracle - 10g
  • Tomcat - 9
  • JDK - 8
  • Eclipse Oxygen
  • Ojdbc6 jar required
First, we need to create the Dynamic Web Project. If you don't know how to do <Click Here>. I have faced a lot of issues before getting the output like 405, No driver class to load, etc. I am using JSP & Servlets in the current explanation. Before started writing the application logic, we need to do the below configuration in the installed tomcat directory.
  • Place OJDBC6.jar in the Tomcat LIB directory.
  • Add this Resource under <GlobalNamingResources> in Server.xml file which is present under the conf directory in Tomcat.
<Resource name="jdbc/myoracle" 
global="jdbc/myoracle" auth="Container" 
type="javax.sql.DataSource" 
driverClassName="oracle.jdbc.driver.OracleDriver"  
url="jdbc:oracle:thin:@vserver12:1521:JTB"  username="jtb"
password="jtb" maxActive="20" maxIdle="10"  maxWait="-1"/>
The below changes need to do in a newly created web project. Add the below Resource-Ref in web.xml file.
<resource-ref>
        <description>Oracle Datasource example</description>
        <res-ref-name>jdbc/myoracle</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
</resource-ref>
Note: Description and res-ref-name you can define any value. But, res-ref-name should be the same as what you have declared name in Resource of server.xml file.

We need to create the context.xml file under the META-INF directory in our application. Context file content should look like the below, values might be changed like path, docBase of the context. These values you simply replace with the application root directory name.
<Context path="/JNDIEX" docBase="JNDIEX" reloadable="false">    <WatchedResource>WEB-INF/web.xml</WatchedResource>{
<Resource name="jdbc/myoracle" auth="Container"
               type="javax.sql.DataSource" username="jtb" password="jtb"
               driverClassName="oracle.jdbc.driver.OracleDriver"
             url="jdbc:oracle:thin:@vserver12.amberroad.com:1521:JTB"
               maxActive="20" maxIdle="10"/>
</Context>
Create the JSP with your own name and add the below context in the body.
<form action="getData" method="POST"> 
<div> 
         <input type="submit" name="clickme" id="clickme" value="Click Me"/> 
</div> 
</form>
I have created the JSP file with the name of the index under web content. File content is the below,
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>JNDI Example</title>
</head>
<body>
<form action="getData" method="POST">
<div>
    <input type="submit" name="clickme" id="clickme" value="Click Me"/>
</div>
</form>
</body>
</html> 
Create a servlet class with the doPost method to load the JNDI context to interact with a database table and show the values in it with the help of PrintWriter. My servlet class complete source is below,
package com.jndi.example;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;

public class JndiTest extends HttpServlet {
    private static final long serialVersionUID = 1L;
    Connection con = null;
    Statement st = null;
    ResultSet rs = null;

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        String loginQuery = "SELECT * FROM USER_LOGIN";
        PrintWriter out = response.getWriter();
        try {
            con = getJNDIConnection();
            st = con.createStatement();
            rs = st.executeQuery(loginQuery);
            while (rs.next()) {
                out.print(rs.getInt(1) + "\t" + rs.getString(2) + "\t" + rs.getString(3)+"\n");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (NamingException e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null)
                    rs.close();
                if (st != null)
                    st.close();
                if (con != null)
                    con.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public static Connection getJNDIConnection() throws SQLException, NamingException {
        Context initContext = new InitialContext();
        Context envContext = (Context) initContext.lookup("java:/comp/env");
        DataSource ds = (DataSource) envContext.lookup("jdbc/myoracle");
        return ds.getConnection();
    }
}
In the above class getJNDIConnection() method will return the JDBC Connection instance with the help of context lookup.

This servlet configuration we have to declare in web.xml file with the help of servlet and servlet-mapping tags. Place the below code in the web.xml file.
    <servlet>
        <servlet-name>getData</servlet-name>
        <servlet-class>com.jndi.example.JndiTest</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>getData</servlet-name>
        <url-pattern>/getData</url-pattern>
    </servlet-mapping>
We are done with the sample application creation, before going run cross check the table name and DB details which we have placed in resources are proper.
For more information, go through this link JNDI datasource examples.

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