如何处理java.security.AccessControlException

Question

I'm trying to launch my applet locally and this is the exception I get:
I don't know why this is happening the mp3 is already located on the jar file, why can't I access it?

SEVERE: null
java.security.AccessControlException: access denied (java.io.FilePermission file:\C:\applet\CairoNightTrainClient.jar!\Music\train.mp3 read)
    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.checkRead(Unknown Source)
    at java.io.FileInputStream.<init>(Unknown Source)
    at com.sun.media.codec.audio.mp3.JS_MP3FileReader.getAudioInputStream(JS_MP3FileReader.java:113)
    at javax.sound.sampled.AudioSystem.getAudioInputStream(Unknown Source)
    at LogicEngine.DJ.createClip(DJ.java:56)
    at LogicEngine.DJ.<init>(DJ.java:42)
    at GUI.JPanelGameApplet$1.run(JPanelGameApplet.java:65)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.awt.EventQueue$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

Applets (or at least untrusted applets) are not allowed to access the local file system. This is kind of a good thing as most people might get upset if random websites had such access.

If you want to access a file go through javax.jnlp (just google it) and it'll provide an API that presents the user with a file chooser to allow applets to read a specific file of their choosing.

If it's just a file that is part of the applet, use either a resource ( Class.getResourceAsStream ) or through an http connection ( URL )