Why am I getting "Can't write file"? from jsp

Question

I have the following code:
public String OpenRAF(String fileName) {
try {
file = new File("http://www.domain/filename.prn");
} catch (java.lang.NullPointerException npe) {
writeError(npe);
} catch (java.lang.IllegalArgumentException iae) {
writeError(iae);
if (!file.isFile()) {
retn = "Not a file:" + file.getAbsoluteFile();
if (!file.canRead()) {
retn = "Can't read file:" + file.getAbsoluteFile();
if (!file.canWrite()) {
retn = "Can't write file:" + file.getAbsoluteFile();
try {
raf = new java.io.RandomAccessFile(file, "rw");
} catch (java.io.FileNotFoundException fnfe) {
rtn = false;
Why am I getting the "Can't write file http://www.domain/filename" from this jsp?
I would like to open this file read,write and update it with the RandomAccessFile api, but I can't seem to get write permissions. I have granted 777 permissions on the file.
Is this a Tomcat file permission issue or something?
Thanks.

Answer 1

Thanks,
But I want to read,write to a file in the application Server. How do I get the path correct?
I want to use something like java.io.RandomAccessFile("somepath", "rw");
I should be able to access the filesystem somehow? The only way I could find the file was using the URL. Whenever I used a relative or absolute path, I could not access the file.
How do I know what the filesystem path is on an application server (Tomcat 4.1) from a Jsp 1.4?
Thanks again