Re: File creation Problem

By default, browsers do not let applets write to the local file system.
This is good thing.  Think of the viruses you could write if they let you
at the disk.  Via a hidden applet you could write just about anything to
the PC and the user wouldn't even know it.

There are a lot of Java things you can't do from a browser but in some
cases the browser has a property to override the default.  In that case the
user gets a dialog asking if it is okay to do the action.  For example, if
the applet wants to make a socket connection to a server other than the
html server, it must override a property which causes a dialog the user
must answer.  I don't think file io can be overridden, however.  Anyone
know for sure?

David Wall
553-5329
AS/400 Toolbox for Java


"Padmanabhan R (RBIN/ACF)" <Padmanabhan.R@in.bosch.com> on 05/17/2000
10:29:40 AM

Please respond to JAVA400-L@midrange.com

To:   JAVA400-L@midrange.com
cc:
Subject:  File creation Problem




Hello ,

          I tried to run the following code , but it is throwing out
the security exception.

import java.applet.*;
import java.awt.*;
import java.io.*;

public class SimpleSaver extends Applet
{

     public void init()
     {
          Button b = new Button("Beans Book");
          b.setFont(new Font("System", Font.BOLD, 36));
          add(b);
          Saver f = new Saver(b);

     }


class Saver
{

public Saver(Button b){


     try{

               FileOutputStream f = new
FileOutputStream("Sav.tmp");
               ObjectOutput s = new ObjectOutputStream(f);
               s.writeObject(b);
               s.flush();
               }catch(Exception e)
                {
                    e.printStackTrace();
                    System.out.println(e);
               }


                    }

  }

}

Exception

E:\jdk1.2\bin\appletviewer.exe     SimpleApplet.html
Working Directory - E:\samples\
Class Path - E:\samples\;
;.;d:\Kawa\classes.zip;e:\jdk1.2\lib\tools.jar;e:\jdk1.2\jre\lib\rt.jar;E:\j

dk1.2\lib\dt.jar;E:\jdk1.2\jre\lib\jaws.jar;E:\jdk1.2\jre\lib\i18n.jar;E:\jd

k1.2\lib\servlet.jar;E:\jdk1.2\lib\as400Driver.jar;i:\proddata\http\public\j

t400\utilities\;i:\proddata\http\public\jt400\lib\jt400.jar
java.security.AccessControlException: access denied (java.io.FilePermission
Sav.tmp write)

     at java.security.AccessControlContext.checkPermission(Compiled Code)

     at java.security.AccessController.checkPermission(Compiled Code)

     at java.lang.SecurityManager.checkPermission(Compiled Code)

     at java.lang.SecurityManager.checkWrite(SecurityManager.java:946)

     at java.io.FileOutputStream.<init>(FileOutputStream.java:96)

     at java.io.FileOutputStream.<init>(FileOutputStream.java:62)

     at SimpleSaver$Saver.<init>(SimpleSaver.java:26)

     at SimpleSaver.init(SimpleSaver.java:13)

     at sun.applet.AppletPanel.run(Compiled Code)

     at java.lang.Thread.run(Thread.java:479)

java.security.AccessControlException: access denied (java.io.FilePermission
Sav.tmp write)

Process Exit...
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