jre1.5以上applet数字签名方法

1.Generate key:
在 command line下输入
keyname 是你自己设的。里叫做叫mysigner 。
keytool -genkey -alias mysigner -keyalg RSA -keysize 1024 -keystore mystore -validity 3650
其中3650是有效天数,回车后将提示你输入一些信息，按提示输入即可。

2.Export key:
将证书导出到证书文件中，在命令行中输入如下指令
keytool -export -alias mysigner  -file mysigner.crt  -keystore mystore
要求你输入密码

3.将class打包
jar cvf applet.jar *.class

4.授权jar文件，在命令行中输入如下指令
jarsigner -keystore mystore applet.jar mysigner

5.每次重新编译完class文件后，重复3，4步骤即可。
以下附applet打开本地源代码：

import java.awt.*;
        import java.awt.event.*;
        import java.io.*;

        import javax.swing.*;

        public class FileAccessApplet extends JApplet {
          private JTextField
            filename = new JTextField(),
            dir = new JTextField();
          private JButton open = new JButton("Open");
          private JEditorPane ep = new JEditorPane();
          private JScrollPane jsp = new JScrollPane();
          private File file;
          public void init() {
            JPanel p = new JPanel();
            open.addActionListener(new OpenL());
            p.add(open);
            Container cp = getContentPane();
            jsp.getViewport().add(ep);
            cp.add(jsp, BorderLayout.CENTER);
            cp.add(p, BorderLayout.SOUTH);
            dir.setEditable(false);
            ep.setContentType("text/html");
            filename.setEditable(false);
            p = new JPanel();
            p.setLayout(new GridLayout(2, 1));
            p.add(filename);
            p.add(dir);
            cp.add(p, BorderLayout.NORTH);
          }

          class OpenL implements ActionListener {
            public void actionPerformed(ActionEvent e) {
              JFileChooser c = new JFileChooser();
              c.setFileFilter(new TextFileFilter());
              // Demonstrate "Open" dialog:
              int rVal = c.showOpenDialog(FileAccessApplet.this);
              if(rVal == JFileChooser.APPROVE_OPTION) {
                file = c.getSelectedFile();
                filename.setText(file.getName());
                dir.setText(c.getCurrentDirectory().toString());
                try {
                  System.out.println("Url is " + file.toURL());
                  ep.setPage(file.toURL());
                  // ep.repaint();
                } catch (IOException ioe) {
                  throw new RuntimeException(ioe);
                }
              }
              if(rVal == JFileChooser.CANCEL_OPTION) {
                filename.setText("You pressed cancel");
                dir.setText("");
              }
            }
          }

          public class TextFileFilter extends
            javax.swing.filechooser.FileFilter {
            public boolean accept(File f) {
              return f.getName().endsWith(".txt")
                || f.isDirectory();
            }
            public String getDescription() {
              return "Text Files (*.txt)";
            }
          }
        }