Accessing files that are there in classes directory

[Raghavender Ammagari]

I have a properties file that is present in WEB-INF/classes...i could read that file as shown below

getClass().getClassLoader().getResourceAsStream("config.properties");

how to do a write process on the same file...the code till now is given below..please help me...

        response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		try
		{		
			Properties prop = new Properties();
			InputStream fis;
			FileOutputStream fos; 
			
			is=this.getClass().getClassLoader().getResourceAsStream("config.properties");
			prop.load(is);			
			
			prop.setProperty("message",request.getParameter("newvalue"));
		
			
            fos =new FileOutputStream(); /// what should be the parameter that need to be sent?
			prop.store(fos,null);				

			response.sendRedirect("index.jsp");
			is.close();
			fos.close();
			out.close();			
		}
		catch(Exception e)
		{
		}

[Raghavender Ammagari]

Please do reply..had expected an immediate solution in coderanch

[Stefan Evans]

Writing/modifying properties files at run-time sounds like trouble to me.
Particularly one that is part of a web application classpath.
There is a reason that you can only GET resources from the classLoader.

To answer your question on how you may be able to do it:

An alternative method to look at is the ServletContext method: getRealPath().
That converts a website relative path into a true location on disk.
so

ServletContext application = getServletConfig().getServletContext();
String filePath = application.getRealPath("/WEB-INF/classes/config.properties");
File configProperties = new File(filePath);

Now you have the File handle, you can open it for writing.

However
- this may not actually resolve to a File on disk. It might be a file in a jar archive, which would not be editable.
- even if it is a file, and you write to it, there is no guarantee it will be read again except by restarting the web application.

What is the use case for this? Are these config properties intended to be edited often?

[Bear Bibeault]

I whole-heartedly agree with Stefan that this is a bad idea. WHat happens when you need to update and redeploy the app?

I always put read/write configuration in the DB where it is independent of the application itself.