Java记事本小程序

import java.awt.Color;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import javax.swing.BoxLayout;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.KeyStroke;

public class NoteBook extends JFrame {

  String tempString="";
  public static void main(String args[]) {
    try {
      NoteBook frame = new NoteBook();
      frame.setVisible(true);
    } catch (Exception e) {
      e.printStackTrace();
    }
  }


  public NoteBook() {
    super();
    getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.X_AXIS));
    setBounds(100, 100, 499, 396);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    final JMenuBar menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    final JMenu File_menu = new JMenu();
    File_menu.setFont(new Font("", Font.PLAIN, 12));
    File_menu.setText("文件");
    menuBar.add(File_menu);

    final JScrollPane scrollPane = new JScrollPane();
    scrollPane.setAutoscrolls(true);
    getContentPane().add(scrollPane);
    final JTextArea jta=new JTextArea();
    jta.setBackground(Color.WHITE);
    scrollPane.add(jta);
    jta.setLineWrap(true);
    scrollPane.setViewportView(jta);
    
    final JMenuItem Open_menu = new JMenuItem();
    Open_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_O, InputEvent.CTRL_MASK));
    Open_menu.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
        JFileChooser fileChooser=new JFileChooser(".");
        fileChooser.setDialogTitle("打开文件");
        fileChooser.addChoosableFileFilter(fileChooser.getFileFilter());
        fileChooser.showOpenDialog(new javax.swing.JFrame());
        File selectFile=fileChooser.getSelectedFile();
        try{
        BufferedReader filein=new BufferedReader(new FileReader(selectFile.getPath()));
        String c=null;
        do{
          c=filein.readLine();
          if(c!=null)
          {
            jta.append(c+"\n");
          }
        }
        while(c!=null);
        filein.close();
        }
        catch(Exception e){
          e.printStackTrace();
        }
        
      }
    });
    Open_menu.setFont(new Font("", Font.PLAIN, 12));
    Open_menu.setText("打开 ");
    File_menu.add(Open_menu);
//保存文件
    final JMenuItem Sava_menu = new JMenuItem();
    Sava_menu.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
        JFileChooser filesaveChooser=new JFileChooser(".");
        filesaveChooser.setDialogTitle("保存文件");
        filesaveChooser.showOpenDialog(new javax.swing.JFrame());
        try{
        BufferedWriter fileout=new BufferedWriter(new FileWriter(filesaveChooser.getSelectedFile()));
        String c=null;
        do{
          String context=jta.getText();
          fileout.write(context);
          fileout.close();
        }
        while(c!=null);
        }
        catch(Exception e){
          e.printStackTrace();
        }
      }
    });
    Sava_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_S, InputEvent.CTRL_MASK));
    Sava_menu.setFont(new Font("", Font.PLAIN, 12));
    Sava_menu.setText("保存 ");
    File_menu.add(Sava_menu);

    final JMenuItem Quit_menu = new JMenuItem();
    Quit_menu.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
        System.exit(0);
      }
    });
    Quit_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, 0));
    Quit_menu.setFont(new Font("", Font.PLAIN, 12));
    Quit_menu.setText("关闭 ");
    File_menu.add(Quit_menu);

    final JMenu Edit_menu = new JMenu();
    Edit_menu.setFont(new Font("", Font.PLAIN, 12));
    Edit_menu.setText("编辑");
    menuBar.add(Edit_menu);

    final JMenuItem Copy_menu = new JMenuItem();
    Copy_menu.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
        try{
          String str=jta.getSelectedText();
          tempString=str;
            
        }
        catch(Exception e){
          e.printStackTrace();
        }
      }
    });
    Copy_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, InputEvent.CTRL_MASK));
    Copy_menu.setFont(new Font("", Font.PLAIN, 12));
    Copy_menu.setText("复制 ");
    Edit_menu.add(Copy_menu);

    final JMenuItem Paste_menu = new JMenuItem();
    Paste_menu.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent arg0){
        try{
          if(tempString.length()>0){
            jta.insert(tempString,jta.getCaretPosition());
          }
        }
        catch(Exception e){
          e.printStackTrace();
        }
      }
    });
    Paste_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, InputEvent.CTRL_MASK));
    Paste_menu.setFont(new Font("", Font.PLAIN, 12));
    Paste_menu.setText("粘贴");
    Edit_menu.add(Paste_menu);

    final JMenu Help_menu = new JMenu();
    Help_menu.setMnemonic('H');
    Help_menu.setFont(new Font("", Font.PLAIN, 12));
    Help_menu.setText("帮助");
    menuBar.add(Help_menu);

    final JMenuItem About_menu = new JMenuItem();
    About_menu.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent arg0) {
        JOptionPane.showMessageDialog(new JFrame(), "Java实现得记事本小程序");
      }
    });
    About_menu.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_A, InputEvent.CTRL_MASK));
    About_menu.setFont(new Font("", Font.PLAIN, 12));
    About_menu.setText("关于记事本 ");
    Help_menu.add(About_menu);

  }

}

基本功能打开保存复制粘贴 主要用到文件操作和IO流