getCodeBase returns null for local applets as of 7u25
From release notes at: Java? SE Development Kit 7 Update 25 Release Notes
Local Applets return NULL for codebase
Beginning with JDK 7u25, an applet's getCodeBase() method will return NULL when the applet is running from the local file system.
Re: getCodeBase returns null for local applets as of 7u25
And getDocumentBase() returns null for local applets as of 7u40. Both are bugs on the part of Oracle, discussed in great detail here:
[Forum denied URL link. Instead Google java security clusterf]
The only way this is going to get resolved is if you report a Java bug citing that article.