FileNotFoundException web.xml

Question

continuing my studies... I'm trying to write some data into a txt file but I'm receiving this exception. I'm using Tomcat 7.0. The EmailList.txt is in the folder, so I don't know what is going one. Can you guys please, help me

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <servlet>
        <servlet-name>AddToEmailListServlet</servlet-name>
        <servlet-class>email.AddToEmailListServlet</servlet-class>
        <init-param>
            <param-name>relativePathToFile</param-name>
            <param-value>/WEB-INF/EmailList.txt</param-value>
        </init-param>
    </servlet>
    <servlet-mapping>
        <servlet-name>AddToEmailListServlet</servlet-name>
        <url-pattern>/addToEmailList</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>join_email_list.jsp</welcome-file>
    </welcome-file-list>
</web-app>

servlet class This class is going to process the data.

package email;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

import business.User;
import data.UserIO;

public class AddToEmailListServlet extends HttpServlet
{   @Override 
    protected void doPost(HttpServletRequest request, 
                          HttpServletResponse response) 
                          throws ServletException, IOException
    {
        // get parameters from the request
        String firstName = request.getParameter("firstName");
        String lastName = request.getParameter("lastName");
        String emailAddress = request.getParameter("emailAddress");

        User user = new User(firstName, lastName, emailAddress);

       //validation
        String message = "";
        String url = "";
        if (firstName.length() == 0 || lastName.length() == 0 || emailAddress.length() == 0) {
            message = "Please fill out all three boxes";
            url = "/join_email_list.jsp";
        }else{
            message = "";
            ServletConfig config = getServletConfig();
            String relativePath = config.getInitParameter("relativePathToFile");
            UserIO.addRecord(user, relativePath);
            url = "/display_email_entry.jsp";
        }
        request.setAttribute("user", user);
        request.setAttribute("message", message);

        //forward request and response

        RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(url);
        dispatcher.forward(request, response);             
    }    
}

The I/O class

package data;

import java.io.; import java.util.;

import business.User;

public class UserIO
{
    public static void addRecord(User user, String filename) throws IOException
    {
        File file = new File(filename);
        PrintWriter out = new PrintWriter(
                new BufferedWriter(new FileWriter(file)));
        out.println(user.getEmailAddress()+ "|"
                + user.getFirstName() + "|"
                + user.getLastName());        
        out.close();
    }
}

Answer 1

The problem is in the code behind UserIO#addRecord() method which you didn't show in your question at all, so it's hard to pinpoint the root cause. But I gather that you just did a new File() on the given relative path. This is a bad idea and well due to the following reasons:

• The new File() operates relative to the current working folder in the disk file system, not to the webapp folder structure. Even then, the leading slash / makes it relative to the disk root.
• The WAR is not necessarily expanded on disk, it can also be expanded in memory insteaad, there's then no means of any valid disk file system path which you could use in new File().
• When the WAR is redeployed or even when the server restarts, all changes in the expanded WAR folder are lost because they are not present in the original WAR file.

Rather write to a file on an absolute path somewhere outside the expanded WAR folder, or use a database instead.