问题
I am trying to build a Java applet, called game, which is something I have never done before (I've always just built standalone applications). My applet works fine when I test it in Eclipse, but when I try putting it on my website, I get the following error in the console:
java.lang.reflect.InvocationTargetException
at com.sun.deploy.util.DeployAWTUtil.invokeAndWait(DeployAWTUtil.java:116)
at sun.plugin2.applet.Plugin2Manager.runOnEDT(Plugin2Manager.java:3541)
at sun.plugin2.applet.Plugin2Manager.createApplet(Plugin2Manager.java:3072)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Plugin2Manager.java:1497)
at java.lang.Thread.run(Thread.java:680)
Caused by: java.security.AccessControlException: access denied (java.util.PropertyPermission user.dir read)
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:374)
at java.security.AccessController.checkPermission(AccessController.java:546)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:532)
at java.lang.SecurityManager.checkPropertyAccess(SecurityManager.java:1285)
at java.lang.System.getProperty(System.java:667)
at java.io.UnixFileSystem.resolve(UnixFileSystem.java:118)
at java.io.File.getAbsolutePath(File.java:501)
at game.<init>(game.java:117)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at sun.plugin2.applet.Plugin2Manager$13.run(Plugin2Manager.java:3060)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:682)
at java.awt.EventQueue.access$000(EventQueue.java:85)
at java.awt.EventQueue$1.run(EventQueue.java:643)
at java.awt.EventQueue$1.run(EventQueue.java:641)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:652)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Exception: java.lang.reflect.InvocationTargetException
It says access denied (java.util.PropertyPermission user.dir read), but I can't figure out where it's trying to read something off the user's file system.
It also says at game.<init>(game.java:117), but I went into my file and made a message output to the console on line 114 and it never got written. I then figured that maybe it was looking at line 117 inside public game(), so I looked for that and it was the start of a listener for a Mouse event. It made sense to me that this would be something that Java would need permission to read, so I deleted all of it and then deleted all the imports for good measure. Then I cleared both Chrome and Java's caches and retried. Same error.
- What does this mean, am I interpreting it incorrectly?
- When it says that line 117, what is it line 117 of?
- Why would this be happening?
- How can I fix it?
- How can I prevent it in the future?
For reference, here is the code for public game():
public game() throws MalformedURLException{
JPanel board = new chessboard();
board.setSize(320, 320);
board.setLocation(0, 0);
System.out.println("Got this far");
Piece wp1 = new Piece(wpawn, a2);
...
Piece bk = new Piece(bking, e8);
board.add(wp1);
...
board.add(bk);
wp1.setLocation(wp1.square.getPoint());
...
bk.setLocation(bk.square.getPoint());
add(board);
repaint();
addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent evt){
for (int i = 0; i < 8; i++){
for (int j = 0; j < 8; j++){
if (squares[i][j].piece != null)
System.out.println(squares[i][j].getPointString() + ": " + squares[i][j].piece.type);
}
}
Point p = evt.getPoint();
if (0 < p.x && p.x < 319 && 0 < p.y && p.y < 319){
Square clicked = getSquare(p);
System.out.println("up: " + clicked.getPointString());
if (clicked.piece != null){
pickedUp = true;
pickedUpPiece = clicked.piece;
}
}
}
public void mouseReleased(MouseEvent evt){
if (pickedUp){
Point p = evt.getPoint();
if (0 < p.x && p.x < 319 && 0 < p.y && p.y < 319){
System.out.println("down: " + getSquare(p).getPointString());
movePiece(pickedUpPiece, getSquare(p).getColumn(), getSquare(p).getRow());
}
pickedUp = false;
}
else System.out.println("Not picked up");
}
});
}
回答1:
The key output of the stack trace is:
at java.io.File.getAbsolutePath(File.java:501)
at game.<init>(game.java:117)
This means that your game.java file, at line 117, is calling getAbsolutePath() on something. Java applets embedded in a browser are not permitted to access the local filesystem.
来源：https://stackoverflow.com/questions/10568345/why-is-my-applet-throwing-an-accesscontrolexception