文件的打开和保存

package com.soft.test;

import java.io.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.filechooser.FileFilter;
import javax.swing.plaf.FileChooserUI;
import java.awt.event.*;
/*
 * 记事本程序
 * */
public class EDitplus extends JFrame implements ActionListener {
 String path = null;
 JTextArea jta = null;
 //菜单
 JMenuBar jmb = null;
 //菜单项
 JMenu jm1 = null;
 JMenuItem jmi1 = null;
 //构造函数
 public EDitplus() {
  //创建jta
  jta = new JTextArea();
  this.setTitle("Editplus");
  jta.setFont(new Font("微软雅黑",1,16));
  jta.setLineWrap(true);
  jta.setAutoscrolls(true);
  this.add(new JScrollPane(jta));
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  this.setVisible(true);
  this.setSize(800,600);
  
  //创建菜单
  JMenuBar jmb = new JMenuBar();
  JMenu jm1 = new JMenu("文件(F)");
  //jm1.setMnemonic('F');
  JMenuItem jmi1 = new JMenuItem("打开(O)");
  JMenuItem jmi2 = new JMenuItem("保存(S)");
  this.setJMenuBar(jmb);
  jmb.add(jm1);
  setJMenuBar(jmb);
  jm1.add(jmi1);
  jm1.add(jmi2);
  jmb.add(jm1);
  //菜单监听
  jmi1.setActionCommand("Open");
  jmi1.addActionListener(this);
  
  jmi2.setActionCommand("Save");
  jmi2.addActionListener(this);
  
  //快捷键监听
  jta.addKeyListener(new KeyListener() { 
   @Override
   public void keyTyped(KeyEvent arg0) {}
   @Override
   public void keyReleased(KeyEvent e) {
    if(e.getKeyCode() == KeyEvent.VK_S && e.isControlDown())
    {
     //当按下Ctrl+S时调用保存
     if (path==null && getTitle().equals("Editplus"))
     {
      //调用有对话框的保存
      dialogSave();
     }else
     {
      //调用无对话框的保存
      noDialogSave();
     }
     setTitle(path);
    }
    if(e.getKeyCode()==KeyEvent.VK_O && e.isControlDown())
    {
     //当按下Ctrl+O时调用打开对话框
     dialogOpen();
    }
   }
   @Override
   public void keyPressed(KeyEvent arg0) {}
  });
 
 }
 
 public static void main(String[] args) {
  EDitplus ep = new EDitplus();
 }
 
 //有对话框的打开
 public void dialogOpen() {
  final JFileChooser jfc1 = new JFileChooser();
  jfc1.setDialogTitle("请选择要打开的文件");
  
  int falg = jfc1.showOpenDialog(null);
  jfc1.setVisible(true); 
  if (falg != JFileChooser.APPROVE_OPTION)
   return ; 
 
  if (!jfc1.getSelectedFile().getName().endsWith(".txt"))
  {
   JOptionPane.showMessageDialog(null, "请打开文本文件!");
   return;
  }
  path = jfc1.getSelectedFile().getAbsolutePath();
  FileReader fr = null;
  BufferedReader br = null;
  String str = null;
  try {
   fr = new FileReader(new File(path));
   br = new BufferedReader(fr);
   while((str=br.readLine())!=null)
   {
    jta.append(str + "\r\n");
   }
   this.setTitle(path);
  } catch (Exception e1) {
   e1.printStackTrace();
   JOptionPane.showMessageDialog(null, "打开失败,请确认打开文件是否为文本文件");
  }
  finally {
   try {
    if (fr!=null)
     fr.close();
    if (br!= null)
     br.close();
   } catch (IOException e1) {
    e1.printStackTrace();
   }
  }
 }
 
 //有对话框的保存
 public void dialogSave() {
  if (jta.getText().equals(""))
   return;
  JFileChooser jfc = new JFileChooser();
  jfc.setDialogTitle("另存为……");
  
  int flag = jfc.showSaveDialog(null);
  jfc.setVisible(true);
  if (flag != JFileChooser.APPROVE_OPTION)
   return ;
  path = jfc.getSelectedFile().getAbsolutePath();
  FileWriter fw = null;
  BufferedWriter bw = null;
  try {
   fw = new FileWriter(path);
   bw = new BufferedWriter(fw);
   bw.write(jta.getText());
   bw.flush();
  } catch (IOException e1) {
   JOptionPane.showMessageDialog(null, "保存失败,请确认磁盘是否可写");
   e1.printStackTrace();
  }finally {
    
   try {
   if (fw!=null) 
    fw.close();
   if (bw!=null)
   bw.close(); 
   } catch (IOException e1) {
    e1.printStackTrace();
   }
   this.setTitle(path);
  }
 }
 
 //无对话框的保存
 public void noDialogSave() {
  FileWriter fw = null;
  BufferedWriter bw = null;
  try {
   fw = new FileWriter(path);
   bw = new BufferedWriter(fw);
   bw.write(jta.getText());
   bw.flush();
  } catch (IOException e1) {
   JOptionPane.showMessageDialog(null, "保存失败,请确认磁盘是否可写");
   e1.printStackTrace();
  }finally {
    
   try {
   if (fw!=null) 
    fw.close();
   if (bw!=null)
   bw.close(); 
   } catch (IOException e1) {
    e1.printStackTrace();
   }
  }
 }
 
 //菜单监听事件
 public void actionPerformed(ActionEvent e) {
  if (e.getActionCommand().equals("Open")) 
  {
   dialogOpen();
  }else if (e.getActionCommand().equals("Save")) {
   if (path==null && this.getTitle().equals("Editplus"))
   {
    //调用有对话框的保存
    dialogSave();
   }else
   {
    //调用无对话框的保存
    noDialogSave();
   }
   this.setTitle(path);
  }
 }
}

用filereader和filewriter来进行读写