问题
With Java 1.6.0.22 i'm not able to open a socket to localhost, the applet is unsigned and is being loaded from the webserver http://localhost/myapplet
If i load it from my computer ip 192.168.1.x and open a socket to that ip it works
With a simple demo that only open a socket it works, but as soon as my applet use JavaScript to Java calls the socket not work.
If I add a crossdomain.xml file the socket works again.
If I allow only 127.0.0.1 it doesn't work
With 1.6.0.17 it works fine
That is similar to question Socket connection to originating server of an unsigned Java applet
But in my case i loading applet from a webserver not from local file system.
回答1:
Via this user having a similar problem i found the relevant oracle bug
access denied (java.net.SocketPermission 127.0.0.1:8080 connect,resolve)
http://www.oracle.com/technetwork/java/javase/6u22releasenotes-176121.html
回答2:
Unsigned applets can only open connections to the host they were loaded from.
回答3:
Oracle knows of this Java problem that severely restricts use of Applets: A Security Vulnerability in the Java Runtime Environment may Allow Code Loaded From the Local Filesystem to Access LocalHost. The translation: if you wish to run Java Applets that talk to a server like Tomcat, you can’t do it with recent Java releases
And their solution is: There is no workaround for this issue.
And how long have they known of this problem? 03-Dec-2008, Bug Id 6704154
You can validate the above information at, https://identity.sun.com/amserver/UI/Login?org=self_registered_users&goto=http://sunsolve.sun.com/show.do?target=home
回答4:
While the documentation says an applet can only open a connection to the host it was loaded from, with Tomcat 5, that statement is not true. I have an applet that invariably generates a, "AccessControlException:access denied (java.net.SocketPermission 66.167.210:80 connect, resolve" even though I've given socket permission to this URL. I'm still trying to solve this issue and am open to any recommendations.
来源：https://stackoverflow.com/questions/4203583/unsigned-applet-socket-javascript