Applet的問題。拒絕存取？

Question

用policytool.exe给applet受予权限

Answer 1

applet对本地文件系统的存取需要特殊授权否则出错

Answer 2

以下是代碼。
你看這樣的程式需要這麼做嗎？而且我也不能確定該給它加什麼規則呀？
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import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import javax.swing.*;
import com.borland.jbcl.layout.*;
import com.borland.dbswing.*;
import java.io.*;
import java.net.*;public class testApplet extends Applet {
  private boolean isStandalone = false;
  private BorderLayout borderLayout1 = new BorderLayout();
  private JTabbedPane jTabbedPane1 = new JTabbedPane();
  private JPanel jPanel1 = new JPanel();
  private BorderLayout borderLayout2 = new BorderLayout();
  private JButton jButton1 = new JButton();
  private JPanel jPanel2 = new JPanel();
  private JTree jTree1 = new JTree();
  private JPanel jPanel3 = new JPanel();
  private JColorChooser jColorChooser1 = new JColorChooser();
  private JPanel jPanel4 = new JPanel();
  private JFileChooser jFileChooser1 = new JFileChooser();
  private JPanel jPanel5 = new JPanel();
  private JPanel jPanel6 = new JPanel();
  private JMenuBar jMenuBar1 = new JMenuBar();
  private JMenu jMenu1 = new JMenu();
  private JMenuItem jMenuItem1 = new JMenuItem();
  private JMenuItem jMenuItem2 = new JMenuItem();
  private JMenuItem jMenuItem3 = new JMenuItem();
  private JMenuItem jMenuItem4 = new JMenuItem();
  private JMenu jMenu2 = new JMenu();
  private JMenuItem jMenuItem5 = new JMenuItem();
  private JMenu jMenu3 = new JMenu();
  private GridLayout gridLayout1 = new GridLayout();
  private BorderLayout borderLayout3 = new BorderLayout();
  private JPanel jPanel7 = new JPanel();
  private JPanel jPanel8 = new JPanel();
  private JPanel jPanel9 = new JPanel();
  private JButton jButton2 = new JButton();
  private JButton jButton3 = new JButton();
  private JPanel jPanel10 = new JPanel();
  private ButtonGroup g1 = new ButtonGroup();
  private JRadioButton jRadioButton1 = new JRadioButton();
  private JRadioButton jRadioButton2 = new JRadioButton();
  private GridLayout gridLayout2 = new GridLayout();
  private VerticalFlowLayout verticalFlowLayout1 = new VerticalFlowLayout();
  private JRadioButton jRadioButton3 = new JRadioButton();
  private JPanel jPanel11 = new JPanel();
  private JPanel jPanel12 = new JPanel();
  private JTextField jTextField1 = new JTextField();
  private JLabel jLabel1 = new JLabel();
  private JToggleButton jToggleButton1 = new JToggleButton();
  private JTextArea jTextArea1 = new JTextArea();
  private BorderLayout borderLayout4 = new BorderLayout();
  private BorderLayout borderLayout5 = new BorderLayout();  private String docPath = "";
  //Get a parameter value
  public String getParameter(String key, String def) {
    return isStandalone ? System.getProperty(key, def) :
      (getParameter(key) != null ? getParameter(key) : def);
  }  //Construct the applet
  public testApplet() {
  }
  //Initialize the applet
  public void init() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  //Component initialization
  private void jbInit() throws Exception {
    this.docPath = getParameter(docPath,"HelloWorldExample.java");
    this.setBackground(UIManager.getColor("Menu.background"));
    this.setLayout(borderLayout1);
    jTabbedPane1.setBackground(Color.orange);
    jPanel1.setLayout(borderLayout2);
    jButton1.setText("jButton1");
    jPanel1.setBackground(SystemColor.activeCaptionBorder);
    jTree1.setBorder(BorderFactory.createLoweredBevelBorder());
    jMenu1.setText("File");
    jMenuItem1.setText("Open");
    jMenuItem2.setText("&New");
    jMenuItem3.setText("-");
    jMenuItem4.setText("!Close");
    jMenu2.setText("Edit");
    jMenuItem5.setText("Null");
    jMenu3.setText("Help");
    jPanel6.setLayout(borderLayout3);
    jPanel6.setToolTipText("");
    jButton2.setText("上一頁");
    jButton3.setText("下一頁");
    jRadioButton1.setBackground(SystemColor.activeCaptionBorder);
    jRadioButton1.setText("jRadioButton1");
    jRadioButton2.setText("jRadioButton2");
    jPanel10.setLayout(verticalFlowLayout1);
    jRadioButton3.setText("jRadioButton3");
    jLabel1.setText("URL");
    jToggleButton1.setText("Get");
    jToggleButton1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        jToggleButton1_actionPerformed(e);
      }
    });

Answer 3

---太長所以分開貼的---------------------------------------------------
    jTextArea1.setBackground(new Color(243, 243, 229));
    jPanel5.setLayout(borderLayout4);
    jPanel5.setBackground(SystemColor.desktop);
    jPanel12.setBackground(SystemColor.desktop);
    jPanel12.setLayout(borderLayout5);
    jPanel11.setBackground(new Color(189, 208, 200));
    this.add(jTabbedPane1, BorderLayout.CENTER);
    jTabbedPane1.add(jPanel1,   "Button");
    jPanel1.add(jButton1, BorderLayout.WEST);
    jTabbedPane1.add(jPanel2,   "JTree");
    jTabbedPane1.add(jPanel3,   "null");
    jPanel3.add(jColorChooser1, null);
    jTabbedPane1.add(jPanel4, "jPanel4");
    jPanel4.add(jFileChooser1, null);
    jTabbedPane1.add(jPanel5, "jPanel5");
    jPanel5.add(jPanel12,  BorderLayout.CENTER);
    jPanel12.add(jTextArea1,  BorderLayout.CENTER);
    jPanel5.add(jPanel11, BorderLayout.NORTH);
    jPanel11.add(jLabel1, null);
    jPanel11.add(jTextField1, null);
    jTextField1.setText(""+this.docPath.toString()+"");
    jPanel11.add(jToggleButton1, null);
    jTabbedPane1.add(jPanel6,  "Layout");
    jPanel6.add(jPanel7,  BorderLayout.NORTH);
    jPanel7.add(jPanel9, "jPanel9");
    jPanel9.add(jButton2, null);
    jPanel9.add(jButton3, null);
    jPanel6.add(jPanel8,  BorderLayout.CENTER);
    jPanel8.add(jPanel10,  "jPanel10");
    jPanel7.setLayout(new CardLayout());
    jPanel8.setLayout(new CardLayout());
    jPanel2.add(jTree1, null);
    jMenuBar1.add(jMenu1);
    jMenuBar1.add(jMenu2);
    jMenuBar1.add(jMenu3);
    jMenu1.add(jMenuItem1);
    jMenu1.add(jMenuItem2);
    jMenu1.add(jMenuItem3);
    jMenu1.add(jMenuItem4);
    jMenu2.add(jMenuItem5);
    jPanel10.add(jRadioButton1, null);
    jPanel10.add(jRadioButton2, null);
    jPanel10.add(jRadioButton3, null);
    g1.add(jRadioButton1);
    g1.add(jRadioButton2);
    g1.add(jRadioButton3);
  }
  //Get Applet information
  public String getAppletInfo() {
    return "Applet Information";
  }
  //Get parameter info
  public String[][] getParameterInfo() {
    return null;
  }  void jButton3_actionPerformed(ActionEvent e) {
    JOptionPane.showMessageDialog(null,"hell0","hello",1);
  }  void getDocument(){
  try{
    this.docPath = this.docPath==null?"":this.docPath;
    this.docPath = (this.docPath.startsWith("http://") || this.docPath.startsWith("ftp://"))?this.docPath:getCodeBase()+"/"+this.docPath;
    //URL url = new URL(this.docPath);
    URI uri = new URI(this.docPath);
    JOptionPane.showMessageDialog(null,uri.toString(),"URI",1);
    File file = new File(uri);
    FileInputStream fio = new FileInputStream(file);
    byte[] docStr = new byte[fio.available()];
    JOptionPane.showMessageDialog(null,String.valueOf(fio.available()),"file length",1);
    fio.read(new byte[fio.available()]);
    jTextArea1.setText(fio.toString());
    fio = null;
  }catch(Exception ex){
    System.out.println("Error during getDocument!" + ex);
    JOptionPane.showMessageDialog(null,"Error:"+ex,"Get document error",1);
  }
}  void jToggleButton1_actionPerformed(ActionEvent e) {
    this.docPath = jTextField1.getText()==null?"HelloWorldExample.java":jTextField1.getText().trim();
    try{
    URI uri1 = new URI(this.docPath.toString());
    JOptionPane.showMessageDialog(null,"uri=","URI",1);
    }catch(Exception ex){
      JOptionPane.showMessageDialog(null,"error"+ex,"action error",1);
    }
    getDocument();
  }}
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純粹的是測試APPLET布局，隻有getDocument()方法是我想取得文件內容的方法。
麻煩幫忙看看
謝謝

Answer 4

另外請問APPLET的javax.swing.*包裡的類是否要安裝了java 1.2以上，並且在IE裡是選擇了java Vxx(適用於APPLET)後才可以瀏覽它，是不是？
我剛才測試了，如果IE裡沒有選擇那一項，就會出現applet couldn't be instantiated的信息，這麼一來，javax.swing.*在APPLET裡豈非相當於沒有用？還是有其它的解決方法？謝謝

Answer 5

就是读取文件内容的问题
File file = new File(uri);
    FileInputStream fio = new FileInputStream(file);
    APPLET不允许读写本地机器上的文件
IE自带的JRE版本比较低，所以如果不使用高版本的JRE，就无法看到含SWING的APPLET。

Answer 6

在你的j2re1.4.0\lib\security目录中找到java。policy文件
加上这个试试:
grant codeBase "file:${java.home}/lib/ext/*" {
  permission java.io.FilePermission "<<ALL FILES>>", "read, read, write, delete, execute";
};