我学Java不到一个月,请高手帮我看下以下的代码,给点好的建议.

package PKLesson6;

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
//import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.RandomAccessFile;
//import java.awt.GridLayout;

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JTextField;

public class Drrp extends JApplet implements ActionListener ...{
    JPanel pl = new JPanel();

    JButton b1 = new JButton("保存");

    JButton b2 = new JButton("读取");

    JLabel l1 = new JLabel("Name");

    JLabel l2 = new JLabel("Phone");

    JTextField tf1 = new JTextField(10);

    JPasswordField pwd = new JPasswordField(10);

    // JTextField tf2=new JTextField(20);
    GridBagLayout gby = new GridBagLayout();

    //GridLayout glt=new GridLayout();
    GridBagConstraints gbc = new GridBagConstraints();

    FileInputStream fis;
    
    BufferedReader br;

    InputStreamReader isr;

    public void init() ...{
        this.getContentPane().add(pl);
        pl.setLayout(gby);
        //gbc.fill=GridBagConstraints.BOTH;
        //gbc=anchor.gridBagConstraints.CETER;
        gbc.gridx = 3;
        gbc.gridy = 1;
        gby.setConstraints(l1, gbc);
        pl.add(l1);

        gbc.gridx = 4;
        gbc.gridy = 1;
        gby.setConstraints(tf1, gbc);
        pl.add(tf1);

        gbc.gridx = 3;
        gbc.gridy = 2;
        gby.setConstraints(l2, gbc);
        pl.add(l2);

        gbc.gridx = 4;
        gbc.gridy = 2;
        gby.setConstraints(pwd, gbc);
        pl.add(pwd);

        gbc.gridx = 3;
        gbc.gridy = 3;
        gby.setConstraints(b1, gbc);
        pl.add(b1);

        gbc.gridx = 4;
        gbc.gridy = 3;
        gby.setConstraints(b2, gbc);
        pl.add(b2);

        b1.addActionListener(this);
        b2.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e) ...{
        if (e.getSource() == b1) ...{
            String n = tf1.getText();
            char[] c = pwd.getPassword();
            String p = String.copyValueOf(c);
            try ...{
                RandomAccessFile raf = new RandomAccessFile("d:/pwd.txt", "rw");
                raf.seek(raf.length());
                //raf.length();
                raf.writeBytes(n + " " + p);
                //raf.writeBytes(n);
                //raf.writeBytes( );
                //raf.writeBytes(p);
            } catch (FileNotFoundException e1) ...{
                e1.printStackTrace();
            } catch (IOException e2) ...{
                e2.printStackTrace();
            }
            tf1.setText("");
            pwd.setText("");
        } else ...{
            if (e.getSource() == b2) ...{
                try ...{
                    fis = new FileInputStream("d:/pwd.txt");
                    
                    isr = new InputStreamReader(fis);
                    br = new BufferedReader(isr);
                    String s = new String();
                    while ((s = br.readLine()) != null)
                         System.out.println(s);
                        //System.out.println(tf1);
                       // System.out.println(pwd);

                    fis.close();
                } catch (FileNotFoundException fn) ...{
                    System.out.println("File not found!");
                } catch (IOException fn) ...{
                    System.out.println("I/O Error");
                }
            }
        }

    }
}