Jndi, Tomcat, Mysql settup and Servlet test

From:

Ming <minghuiyu@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 18 Nov 2007 00:15:11 -0800 (PST)

Message-ID:

<7d489677-70f8-4204-96b1-28da0304cd6b@s12g2000prg.googlegroups.com>

Tomcat version 5.5.25

I am trying to set up and test mysql jndi connection but cannot make
it.

Can only display:
Servlet NewServlet at /BeerV1
000000000000000000000000000
111111111111111111111111111

Why Statement st = con.createStatement(); and ResultSet rs =
st.executeQuery("select * from users"); cannot be executed?

Thanks

****************Code Snippets**********************

Code snippet from $tomcat/conf/server.xml

<GlobalNamingResources>
    <Environment
      name="simpleValue"
      type="java.lang.Integer"
      value="30"/>
    <Resource
      name="jdbc/test"
      type="javax.sql.DataSource"
      maxActive="4"
      maxIdle="2"
      username="test"
      maxWait="5000"
      driverClassName="com.mysql.jdbc.Driver"
      validationQuery="select * from users"
      password="test"
      url="jdbc:mysql://localhost:3306/test/>
    <Resource
      auth="Container"
      description="User database that can be updated and saved"
      name="UserDatabase"
      type="org.apache.catalina.UserDatabase"
      factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
      pathname="conf/tomcat-users.xml"/>
  </GlobalNamingResources>

Code from $myapplication/WEB-INF/web.xml

  <description>MySQL Test App</description>
  <resource-ref>
      <description>DB Connection</description>
      <res-ref-name>jdbc/test</res-ref-name>
      <res-type>javax.sql.DataSource</res-type>
      <res-auth>Container</res-auth>
  </resource-ref>

Test code:

import java.io.*;
import java.net.*;

import javax.servlet.*;
import javax.servlet.http.*;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class NewServlet extends HttpServlet {

    /**
    * Processes requests for both HTTP <code>GET</code> and
<code>POST</code> methods.
    * @param request servlet request
    * @param response servlet response
    */
    protected void processRequest(HttpServletRequest request,
HttpServletResponse response)
    throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        try {

            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet NewServlet</title>");
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet NewServlet at " +
request.getContextPath () + "</h1>");
            try {
            // TODO code application logic here

            Context ctx = new InitialContext();
            out.println("000000000000000000000000000<br>");

            DataSource ds = (DataSource)ctx.lookup("java:comp/env/jdbc/
test");
            out.println("111111111111111111111111111<br>");

            Connection con = ds.getConnection();
            out.println("222222222222222222222222222<br>");

            Statement st = con.createStatement();
            out.println("333333333333333333333333333<br>");

            ResultSet rs = st.executeQuery("select * from users");
            out.println("444444444444444444444444444<br>");

            while (rs.next()) {
                out.println(rs.getString("first_name"));
            }
            rs.close();
            st.close();
            con.close();
            }
         catch (SQLException ex) {

Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null,
ex);
        } catch (NamingException ex) {

Logger.getLogger(NewClass.class.getName()).log(Level.SEVERE, null,
ex);
        }

            out.println("</body>");
            out.println("</html>");

        } finally {
            out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet
methods. Click on the + sign on the left to edit the code.">
    /**
    * Handles the HTTP <code>GET</code> method.
    * @param request servlet request
    * @param response servlet response
    */
    protected void doGet(HttpServletRequest request,
HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
    * Handles the HTTP <code>POST</code> method.
    * @param request servlet request
    * @param response servlet response
    */
    protected void doPost(HttpServletRequest request,
HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
    * Returns a short description of the servlet.
    */
    public String getServletInfo() {
        return "Short description";
    }
    // </editor-fold>
}