Java PlugIn & PolicyTool
(Applet writes to a local file)
- Click here to download the file involved in this example.
Currently works with IE only.
Java Security Example- Writing Files
to the users local file system. A policy needs to be created by the
user that allows the applet to write/read to that directory.
- When you run this example, I will want to download the Java Plug-in
1.3.0_01 from Sun's site.
Note: It looks like you must have this version. Not
an earlier or later version. I'm not sure why Sun (or whoever) has
designed it this way.
- At the DOS prompt, execute the program: policytool.exe
- When you installed the Java Plug-in (includes JRE) this program
was installed also. If you get a bad command, you may want to
specify the full pathname.
Ex: C:\Program Files\JavaSoft\JRE\1.3.0_01\bin\policytool.exe
- Policy Tool Steps: Create a policy file, if one does not exist.
- The first time you run policytool.exe you may get an error: Could
not find policy file: <file name>. That's OK. Make
sure you right down the full pathname of the file name it is looking
Ex: c:\winnt\Profiles\<your user id>\.java.policy
- If you did not have a policy file, the click on File, Save.
- Next type in the policy file name as it appeared in the error.
- Now you have a policy file in the default location.
- Policy Tool Steps: Create appropriate policies.
- Click on "Add Policy Entry"
- CodeBase = file:/c:/test
- Signed By: <leave blank>
- Click on "Add Permission" to add the following
- File Permission to Read & Write.
- Target Name: c:/test/MyAppletWriteFile.txt
- read, write
- Click on "OK"
- (Optional) Property Premissions - If you plan to use
the link that runs getDebugProperties(), you will need to
add the following permissions:
- PropertyPermission, user.home, read
- PropertyPermission, java.home, read
- Click on "Done"
- File, Save.
- Now in your Windows Explorer, launch the web page:
MyAppletWriteFile.html in the c:\test directory.
Warning: While testing, if you make any
changes to the policy file you must exit all browser windows, then
reopen the browser and then the web page.
- On this new web page, click on the first 3 links under "Using
- The 4th link will give Security Errors unless you create the
PropertyPermissions listed above.
- Once you are successful with the above steps, you may try to setup the
policy tool to allow my web page to write to your c:\test directory.
Click Here to
launch the same web page from my site.
Hint: Set up the same permissions above. You will need to
add another policy entry and use the following CodeBase: