Problems accessing parameters, files - problems in general.

Question

I've been posting my problems to comp.lang.java.programmer but Google Groups is exceedingly slow to update and I've been stuck on this for nearly two whole days:
I am developing what will be a series of web utilities for our company and our client's company. Unfortunately I am hampered by the fact that my Java is not that good having come from a C++ background.
My current setup is Windows XP, JDK 1.3.1.07 (which is what our client is running), Tomcat 4.1 for testing on my local box.
I've been middling around with small examples and decided to do something slightly more complex. What I am trying to do is access a file that is described in web.xml as a parameter. However when ever I run the program it is unable to find the file. All the documentation I have (web-based plus a Professional Java Server Programming J2EE Edition - way over my head) either skims across it/takes it as read it will be set up correctly/doesn't touch it at all.
I thought I was trying to access the wrong directory so I mapped the file to the root of C and still can't access it - it always comes back as null. Also between attempts I restart the Tomcat server so it always loads in the web.xml file.
This is my web.xml:
<?xml version="1.0" encoding="ISO-8859-1"?>
<!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>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>
  <servlet>
    <servlet-name>LogIn</servlet-name>
    <servlet-class>website.LogIn</servlet-class>
    <init-param>
      <param-name>passwordFile</param-name>
      <param-value>C:\\passwords.txt</param-value>
    </init-param>
  </servlet>
  <servlet-mapping>
    <servlet-name>LogIn</servlet-name>
    <url-pattern>/logged</url-pattern>
  </servlet-mapping>
</web-app>And the Java:
package website;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
*  Handles the login to the administrators section of the website
public class LogIn extends HttpServlet
    private String passwordFile;
    /** Read the password file from the location specified
     *  by the passwordFile initialization parameter.
    public void init(ServletConfig config) throws ServletException
        super.init(config);
        passwordFile = config.getInitParameter("passwordFile");
        System.out.println(passwordFile);
        if (passwordFile == null)
            System.out.println("The \"passwordFile\" property must be set to a file name");
        try
        catch (Exception e)
            System.out.println("Error: Unable to read passwordFile.");
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
}It was suggested on comp.lang.java.programmer to check the path that the system was thinking I was searching which I did by inserting this code fragment:
     // initialise the servlet and load password(s)
//     super.init(config);
//     passwordFile = config.getInitParameter("passwordFile");
     // added code
     passwordFile = "passwords.txt";
     File f = new File( passwordFile );
     System.out.println( f.getAbsolutePath() );
     // added code.
        ...This lead me to learn that the directory being returned was:
C:Program Files\Apache Group\Tomcat 4.1\passwordFile.txt
Which is strange since I would of thought that the lowest directory
that is visible to the class would of been ROOT (hence it's name).
Does this mean if I copy the passwordFile.txt to the above directory
it would work? Actually no. I still can't get the filename as a
parameter from web.xml which is frustrating. If you could give me any
pointers on what might be wrong then that would be cool.
I thought I could move forward by accessing the file directly. But no: An addition of f.exists() to check that the file exists returns false. I've now got a copy of passwords.txt in every single directory from the classes directory all the way down to C:\ and it still doesn't work.
I hope someone can help out here since this is very frustrating to be stuck on something so basic as file handling.
Graham Reeds,
http://omnieng.co.uk | [email protected]

Answer 1

I can see how this is frustrating but it should be fixable. The last example you posted won't work because you have "passwords.txt" instead of "c:/passwords.txt".
If you're still looking for a solution could you cut and paste the following code into your servlet code and then post the results?
// Check that init param is read correctly
String filename = config.getInitParameter("passwordfile");
System.out.println("config param = " + filename);
// try filenames
String[] filenames = new String[] {"c:/passwords.txt", "c:\\passwords.txt", "passwords.txt"};
for (int i=0; i < filenames.length; ++i) {           
   File file = new File(filenames);
System.out.println("File " + filenames[i] + " - exists = " + file.exists());
System.out.println("Abs path = " + file.getAbsolutePath());
This is based on the file c:\passwords.txt existing - if I have the wrong filename, please adjust. Also, you may need to change <i> to [[i]i] in a couple of places.