Applet trying to write print commands to port LPT1

Question

My applet trying to write print commands to port LPT1 and I was able to self sign and run the applet. But I am getting the following type of error:
java.security.AccessControlException: access denied (java.io.FilePermission LPT1 write)
Do I really need a policy file and then grant permission for File writing?
Why self signing is not helping to get the permission for File writing ?
I am using latest jdk1.5 jvm and IE 6.x.
Please clarify.

Answer 1

1. Make sure your applet is run with SUN jre (use the HtmlConverter.exe in the jdk\bin directory)
2. Make sure your signed jar is the one referenced in the html archive tag (did you get the do you trust question)
3. If the method is called from untrusted code (javascript for example) use doprivileged.
4. Some 1.3 versions of the jre only trusts CA signed applets.
If this applet is for everyone (grandma's PC) than signing should be a good way to get the applet
to do what you want.
If it's for a company that has Admin controlled desktops a policy would be better.
I think a good configuration would be a keystore and policy on the company's
Intranet to be used by everyone and if so needed a keystore and policy in the user home
folder to be edited only by admins. Add the 2 keystores to the java.security and the
admins can configure any special privileges to special applets (like IE security zones
but more detailed).
Add the following line to all codebases: "grant { " section in the java.policy/
permission java.lang.RuntimePermission "usePolicy";
Now the user does not have the option of "do you trust" for signed applets. I think this
is a verry good idea because anyone with a jdk can sign their jar.     
http://forum.java.sun.com/thread.jsp?forum=63&thread=409341
4th post explaining how to set up your own policy with your own keystore