I just realized that I overlooked one fact about getServletContext(): it's new
in version 2.1 of the Servlet API, and basically unusable in today's servlet
engines...
Michael
Michael Caines wrote:
> Is there a way for a servlet to alter and save a Properties object to a
> file on the server? I want to allow the user to make changes to a
> profile (a .properties file on the server), and have them persist on the
> server without using a database.
>
> Here are the things I'm looking at:
>
> The java.util.Properties class has methods for loading and saving a
> Properties object from a stream, but no setter method for changing
> individual properties.
>
> sun.servlet.http.HttpServer::loadProperties() No saveProperties()
> method, plus same problems as above once you get the Properties object.
> Also, it's not part of the official Java spec.
>
> There is the java.io.File class. This usually results in coding some
> system-dependent filenames which I would like to avoid if possible. I
> could also scrap the Properties approach and create my own flat-file for
> storing profiles. However, I'd like to use a .properties file, since it
> seems naturally suited for the task.
>
> 1) java.lang.Class::getResource() is read-only
> 2) ServletConfig::getServletContext().getResource() is read-only
> Jason Hunter's article in JavaWorld mentions using a resource for output
> as well. This is done by taking the resource's URL object, creating a
> URLConnection object via URL::openConnection(), invoking
> setDoOutput(true) on the URLConnection, and using
> URLConnection::getOutputStream() to open an output stream to the
> resource. I haven't tried writing to a .properties file with number 2
> above, but trying it with number 1 in some test code resulted in a
> "protocol doesn't support output" Exception. Maybe number 2 would be
> able to work by using the ServletClassLoader, and not the
> SystemClassLoader--I'm not sure.
>
> java.util.PropertyResourceBundle::getBundle() read-only
>
> There is a com.sun.server.util.ExProperties class, which is a direct
> subclass of java.util.Properties. It adds functionality for setting
> properties, but it's not part of the official Java spec. If there is a
> method of doing this that uses only java.* classes, I would prefer to
> use it.
>
> Michael
>
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