Caching files

[mzimmer74]

Hi all,
I'm new to the Droid (came from Windows mobile) and want to get into programming for it. I'm slowly working my way through the various possibilities and have managed to write a program that downloads an image from a web page and displays it on my screen. However, what I'd like to do is make a local copy of it so when I next run the program it doesn't have to download it again. Now, I know that I could just save it to a file, but I came across an older suggestion on a web site to use the System Cache. They recommend doing this:

URL url = new URL(strUrl);
URLConnection connection = url.openConnection();
connection.setUseCaches(true);
Object response = connection.getContent();
if (result instanceof Bitmap) {
  Bitmap bitmap = (Bitmap)response;
}

Now, it seems like they were saying that this would use the System Cache to automatically save the file and then if I were to call the same method with the same URL it would check the cache first and then download if needed. However, I can't get it to work. I keep getting an exception thrown and can't trace it back to where it's happening (Eclipse won't give me enough info). All I changed in my code was to replace my previous "LoadImage" method with the above.

Here's my questions:
1. Is the above code a legitimate way to load the image?
2. If so, is there possibly a permission that I'm missing?
3. In general, what Uses-Permission do I need to give to my applications to enable them to manipulate the filesystem?
4. Is there some better way to accomplish what I'm trying to do?

Thanks for any help.