文件对话框的使用

import java.awt.BorderLayout;
import java.awt.FileDialog;
import java.awt.TextArea;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class dd extends JFrame{
 private static String filepath=null;;
 private static TextArea tf = new TextArea("",30,40,TextArea.SCROLLBARS_BOTH);
 private static JButton button1=new JButton("打开文件");
 private static JButton button2=new JButton("保存文件");
 private JPanel panel1=new JPanel();
 public dd(){
  this.setTitle("传文件");
  this.setVisible(true);
  this.add(tf,BorderLayout.NORTH);
  
  panel1.add(button1);
  panel1.add(button2);
  this.add(panel1,BorderLayout.CENTER);
  this.pack();
 }
 public static void main(String[] args) {
  new dd();
  button1.addActionListener(new ActionListener(){

   public void actionPerformed(ActionEvent e) {
    BufferedReader br=null;
     FileDialog dialog=new FileDialog(new JFrame(),"打开 指定文件 ",FileDialog.LOAD);
     dialog.setVisible(true);
     filepath=dialog.getDirectory()+dialog.getFile();
     File file=new File(filepath);
     try {
      br=new BufferedReader(new FileReader((file)));
      String content;
      StringBuffer sb=new StringBuffer();
      while((content=br.readLine())!=null){
       sb.append(content+"\n");
      }
      tf.setText(sb.toString());//添加的内容会覆盖原有的
      tf.append(sb.toString());//在原有的基础上追加
     } catch (Exception e1) {
      e1.printStackTrace();
     }
     finally{
      try {
       br.close();
      } catch (IOException e1) {
       e1.printStackTrace();
      }}
   }
  });

  
  
  button2.addActionListener(new ActionListener(){

   public void actionPerformed(ActionEvent e) {
     FileDialog dialog=new FileDialog(new JFrame(),"保存文件 ",FileDialog.LOAD);
     dialog.setVisible(true);
     filepath=dialog.getDirectory()+dialog.getFile();
     File file=new File(filepath);
     FileOutputStream fos =null;
     
     try {
     fos = new FileOutputStream(file);
     String content=tf.getText();
     byte [] b=content.getBytes();
    
     fos.write(b);
     fos.close();//关闭输出管道
      } catch (Exception e1) {
       e1.printStackTrace();
      }
   }
  });
  
 }
}