Java Reflection problem in applet under Sun plugin and Netscape. 
 
I want to be able to call a showDocument using reflection, i.e.: 
-- 
Object o  = getAppletContext(); 
Method myMethod  = o.getClass().getMethod("showDocument",  
                                          new Class[]{URL.class}); 
myMethod.invoke(o, new Object[]{new URL(myUrl)}); 
--- 
 
Under Internet Explorer w/ MS JVM, this works fine, however,  
under Netscape, I'll get the following error: 
java.lang.IllegalAccessException: netscape/applet/MozillaAppletContext
 
With the plugin, I'll get: 
java.security.AccessControlException: access denied 
(java.lang.RuntimePermission 
accessClassInPackage.sun.plugin.viewer.context) 
    at java.security.AccessControlContext.checkPermission(AccessControlContext.java:270)
    at java.security.AccessController.checkPermission(AccessController.java:401)
    at java.lang.SecurityManager.checkPermission(SecurityManager.java:542)
    at java.lang.SecurityManager.checkPackageAccess(SecurityManager.java:1513)
    at sun.applet.AppletSecurity.checkPackageAccess(AppletSecurity.java:166)
    at java.lang.Class.checkMemberAccess(Class.java:1408) 
    at java.lang.Class.getMethod(Class.java:950) 
 
How can I make this work under the Sun plugin and Netscape (MS already
works fine), without having users change any setting etc (so run out 
of the box). 

---

Clarification of Question by jpdeckers-ga on 28 Apr 2002 23:17 PDT

The reflection is needed for an obfuscation-step 

This is a security issue. In order to get around it you will need to
install a SecurityManager (more info at:
http://java.sun.com/j2se/1.3/docs/api/java/lang/SecurityManager.html )
that allows access to the packages you require.
Even more info here:
http://java.sun.com/j2se/1.3/docs/guide/security/smPortGuide.html

The previous answer is incorrect. You cannot install a security
manager by default, because Netscape won't let you.

Why do you need to use reflection?

Here's what you could do. Suppose, for example, you want to call a
variety of different methods depending on the value of some string
variable. You should be able to simulate reflection, using something
like:

if (methodName.equals ("showDocument")) getAppletContext
().showDocument (myUrl);
else if (methodName.equals ("foo")) foo (bar);

etc.

It's not elegant, but it works.

Again, if this doesn't help, could you please explain why you need to
use reflection.

This happens because when you get the AppletContext object you are
getting a sun implementation of it with a sun.* package name. 
Permission to access classes is denied to applets in the JRE
java.security file.  This makes your code work though:

Object o  = getAppletContext();
Class c = java.applet.AppletContext.class;
Method myMethod  = c.getMethod("showDocument", new
Class[]{URL.class});
myMethod.invoke(o, new Object[]{new URL(myUrl)});

because you are forcing the issue to access a java package class.

Alternatively, you can sign the applet and grant it:
RuntimePermission (accessClassInPackage.sun.)