java.security.AccessControlException thrown ... - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

java.security.AccessControlException thrown when applet calls java.beans.Introspector.setBeanInfoSearchPath()

Symptoms

When running an applet in a browser using the Sun JRE, an AccessControlException is thrown in the execution of Introspector.setBeanInfoSearchPath():

java.security.AccessControlException: access denied (java.util.PropertyPermission * read,write)
    at java.security.AccessControlContext.checkPermission(Unknown Source)
    at java.security.AccessController.checkPermission(Unknown Source)
    at java.lang.SecurityManager.checkPermission(Unknown Source)
    at java.lang.SecurityManager.checkPropertiesAccess(Unknown Source)
    at java.beans.Introspector.setBeanInfoSearchPath(Unknown Source)
    at ....

The same applet runs under the Microsoft VM.

Cause

The Introspector.setBeanInfoSearchPath() method call can change the list of package names used for finding BeanInfo classes. If more than one applet is running in the VM, an untrusted applet could call this method to redirect other applets to look up BeanInfo in unexpected packages. This is a security hole.

A security check for java.util.PropertyPermission was added to this method in the JRE to address the security concern. If the applet is unsigned and it calls into this method, an AccessControlException will be thrown.

Resolution

The workaround is to either:

1. Sign the applet using the JDK jarsigner tool, so that the applet runs as a trusted applet and has permissions to call the Introspector.setBeanInfoSearchPath() method.
2. Rearchitect the applet code to avoid the call to Introspector.setBeanInfoSearchPath(). For example, instead of relying on the BeanInfo search path, use a fully qualified package name for looking up the BeanInfo.

Related Information

        See jarsigner - JAR Signing and Verification Tool.