CAN NOT DELETE FILE ?!

Question

This is odd:
I have listed certain files on a JSP page. When I click the filename you are prompted to a another page where you can modify information the file contains. If I try to delete the file, the file simply exists???
The file is a serialized object, but that should not cause the problem?
I am using TomCat 4.0.2
File f = new File( "filename.dat" );
if( f.exists() && f.canWrite() ){
if( f.delete() )
     System.out.println("File deleted.");                                   
The scope is session on the JSP page.
Any help would be great!!
-Eki

Answer 1

I am having the same problem too.
After reading so many article in the forum regarding to this issue and the solution other people posted. None of them is useful.
They are all wrong.
It is not because of the thread issue. It is not because of it is not exist or something else
It is because, no matter what webserver you are using, the jsp in default is prohibit you from delete any file in the server side.
After long time of testing, I find out the solution.
I am using the J2EE implementation server, but I believe other is similar.
1. search for the server.policy file
Mine is C:\j2sdkee1.3.1\lib\security\server.policy
I think other is webserver is similar
Inside this section
grant {
permission java.net.SocketPermission "*", "connect";
permission java.util.PropertyPermission "*", "read";
// workaround missing doPrivileged blocks in javamail
permission java.io.FilePermission "${com.sun.enterprise.home}${/}lib${/}j2ee.jar", "read";
permission javax.security.auth.PrivateCredentialPermission "javax.resource.spi.security.PasswordCredential * \"*\"", "read";
permission javax.security.auth.PrivateCredentialPermission "javax.resource.spi.security.GenericCredential * \"*\"", "read";
3. Insert this line in the between the grant block
permission java.io.FilePermission "<<ALL FILES>>", "read,write,delete";
4. Restart your server, it should work now.