java.lang.ClassNotFoundException Thrown by the ClassLoader on the com.ms.security Package

Symptoms

When running an applet in a browser using the Sun Java^TM Runtime Environment (JRE^TM), a java.lang.ClassNotFoundException is thrown by the ClassLoader on the com.ms.security package. The same applet runs without any error under the Microsoft Virtual Machine (VM).

Cause

The Microsoft VM provides the proprietary com.ms.security package for applets and applications to access the security policy at runtime. Because this package is not available in the Sun JRE, a java.lang.ClassNotFoundException is thrown when the applet runs in a browser.

Resolution

Migrate the applet source from the com.ms.security package to the java.security package by using similar classes.

For example, the following applet uses com.ms.security.PolicyEngine to assert the network I/O permission before connecting to a URL:

public class AssertPermissionApplet extends java.applet.Applet
{
    public void init()
    {
        try
        {     
            // Assert permission on network I/O
            com.ms.security.PolicyEngine.assertPermission
            (com.ms.security.PermissionID.NETIO); 
            java.net.URL url = new java.net.URL("http://randomhost/randomfile");
            .....
        } catch (java.net.MalformedURLException mue) {
        }
        catch (java.io.IOException ioe) {
        }
      } // init
}

In the Java technology, java.security.AccessController provides similar functionality for permission assertion. The following source code displays the functionality after migration:

public class AssertPermissionApplet extends java.applet.Applet
{
    public void init()
    {
        try
        {     
            // Assert permission on network I/O
            java.security.AccessController.checkPermission(new java.net.SocketPermission("randomhost:80", "connect,accept"));
            java.net.URL url = new java.net.URL("http://randomhost/randomfile");
            .....
        } catch (java.net.MalformedURLException mue) {
        }
        catch (java.io.IOException ioe) {
        }
      } // init
}

See the Java^TM SE technology API documentation for more details about security.

Related Information

        See Security.