Applet代码运行出错啦！

1）文件名：ButtonApplet.java
import javax.swing.*;
import java.awt.event.*;public class ButtonApplet extends JApplet { public void init() {
JFileChooser fileChooser = new JFileChooser("D:\\");
fileChooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
fileChooser.setDialogTitle("open folder");
int ret = fileChooser.showOpenDialog(null);
if (ret == JFileChooser.APPROVE_OPTION) {
// path
System.out.println(fileChooser.getSelectedFile().getAbsolutePath());
}
}
}2）文件名：ButtonApplet.html
<html>
  <head>
    <title>Applet Demo</title>
  </head>
  <body>
    <applet code="ButtonApplet.class" width="400px" height="400px"></applet>
  </body>
</html>3）C:\Program Files\Java\jre1.5.0_18\lib\security\java.policy加上下面的语句：grant codeBase "file:${java.home}/lib/ext/*" {
permission java.io.FilePermission "<<ALL   FILES>>", "read,  read,  write,   delete,   execute";
};
sun控制台错误提示：
java.security.AccessControlException: access denied (java.io.FilePermission ShellFolder: 0x11 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 sun.awt.shell.Win32ShellFolder2.listFiles(Unknown Source)
at sun.awt.shell.ShellFolder.listFiles(Unknown Source)
at sun.awt.shell.Win32ShellFolderManager2.isFileSystemRoot(Unknown Source)
at sun.awt.shell.ShellFolder.isFileSystemRoot(Unknown Source)
at javax.swing.filechooser.FileSystemView.isFileSystemRoot(Unknown Source)
at javax.swing.filechooser.FileSystemView.createFileObject(Unknown Source)
at javax.swing.filechooser.WindowsFileSystemView.createFileObject(Unknown Source)
at javax.swing.JFileChooser.<init>(Unknown Source)
at javax.swing.JFileChooser.<init>(Unknown Source)
at ButtonApplet.init(ButtonApplet.java:7)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

[b]怎么还报没有权限？[/b]

解决方案 »

  1.   

        grant codeBase "file:${java.home}/lib/ext/area.jar" {
            permission java.io.PropertyPermission "user.home", "read";
            permission java.io.FilePermission "${user.home}${/}test${/}*", "write";
        };The codeBase "file:${java.home}/lib/ext/area.jar" part of this entry guarantees that any permissions specified by this entry will apply only to the area.jar. The java.io.PropertyPermission permits access to properties. The first argument, "user.home", names the property, and the second argument, "read", indicates that the property can be read. (The other choice is "write".)The java.io.FilePermission permits access to files. The first argument, "${user.home}${/}test${/}*", indicates that area.jar is being granted permission to access all files in the test directory that is in the user's home directory. (Note that ${/} is a platform-independent file separator.) The second argument indicates that the file access being granted is only for writing. (Other choices for the second argument are "read", "delete", and "execute".) 
      

  2.   

    ${java.home}/lib/ext/目录下根本没有area.jar!
    有中文解释就好了。
      

  3.   

    C:\Program Files\Java\jre1.5.0_18\lib\security\java.policy加上下面的语句： 
    grant codeBase "file:${java.home}/lib/ext/*" {
            permission java.io.PropertyPermission "user.home", "read";
            permission java.io.FilePermission "${user.home}${/}test${/}*", "read";
        };
    错误还是发生了：
    Exception in thread "AWT-EventQueue-3" java.security.AccessControlException: access denied (java.util.PropertyPermission user.dir 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.checkPropertyAccess(Unknown Source)
    at java.lang.System.getProperty(Unknown Source)
    at java.io.Win32FileSystem.getUserPath(Unknown Source)
    at java.io.Win32FileSystem.resolve(Unknown Source)
    at java.io.File.getAbsolutePath(Unknown Source)
    at javax.swing.filechooser.WindowsFileSystemView.isFloppyDrive(Unknown Source)
    at javax.swing.plaf.basic.BasicFileChooserUI$BasicFileView.getIcon(Unknown Source)
    at javax.swing.JFileChooser.getIcon(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI$DirectoryComboBoxRenderer.getListCellRendererComponent(Unknown Source)
    at javax.swing.plaf.basic.BasicListUI.updateLayoutState(Unknown Source)
    at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(Unknown Source)
    at javax.swing.plaf.basic.BasicListUI$Handler.valueChanged(Unknown Source)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
    at javax.swing.DefaultListSelectionModel.fireValueChanged(Unknown Source)
    at javax.swing.DefaultListSelectionModel.changeSelection(Unknown Source)
    at javax.swing.DefaultListSelectionModel.changeSelection(Unknown Source)
    at javax.swing.DefaultListSelectionModel.setSelectionInterval(Unknown Source)
    at javax.swing.JList.setSelectedIndex(Unknown Source)
    at javax.swing.plaf.basic.BasicComboPopup.setListSelection(Unknown Source)
    at javax.swing.plaf.basic.BasicComboPopup.access$300(Unknown Source)
    at javax.swing.plaf.basic.BasicComboPopup$Handler.itemStateChanged(Unknown Source)
    at javax.swing.JComboBox.fireItemStateChanged(Unknown Source)
    at javax.swing.JComboBox.selectedItemChanged(Unknown Source)
    at javax.swing.JComboBox.contentsChanged(Unknown Source)
    at javax.swing.AbstractListModel.fireContentsChanged(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI$DirectoryComboBoxModel.setSelectedItem(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI$DirectoryComboBoxModel.addItem(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI$DirectoryComboBoxModel.access$800(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI.doDirectoryChanged(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI.access$1100(Unknown Source)
    at javax.swing.plaf.metal.MetalFileChooserUI$5.propertyChange(Unknown Source)
    at java.beans.PropertyChangeSupport.firePropertyChange(Unknown Source)
    at java.beans.PropertyChangeSupport.firePropertyChange(Unknown Source)
    at java.awt.Component.firePropertyChange(Unknown Source)
    at javax.swing.JFileChooser.setCurrentDirectory(Unknown Source)
    at javax.swing.JFileChooser.<init>(Unknown Source)
    at javax.swing.JFileChooser.<init>(Unknown Source)
    at MyFrame.show(ButtonApplet.java:29)
    at handle.actionPerformed(ButtonApplet.java:19)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForHierarchy(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)