exam12_6.java

java学习课件

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class File_Dialog extends JFrame implements ActionListener
{
  Button bt1,bt2;
  TextArea text=new TextArea(12,70);
  Label lb1=new Label("执行下列操作",1);
  FileDialog fileLoad,fileSave; 
  public File_Dialog() 
   {
    bt1=new Button("编辑文件");
    bt2=new Button("保存文件");
    Container pane=this.getContentPane();
    fileLoad=new FileDialog(this,"打开文件对话框",FileDialog.LOAD);
    fileSave=new FileDialog(this,"保存文件对话框",FileDialog.SAVE);
    pane.setLayout(new FlowLayout());
    JPanel p1=new JPanel();
    p1.add(bt1);
    p1.add(bt2);
    bt1.addActionListener(this);
	bt2.addActionListener(this);
	pane.add(lb1);
	pane.add(p1);
	pane.add(text);
	this.setTitle("文件对话框示例");
	this.setVisible(true);
	this.setSize(600,300);
	this.setDefaultCloseOperation(3);
   }
  public void actionPerformed(ActionEvent e)
   {
	if(e.getSource()==bt1)
	{
	 fileLoad.setVisible(true);
	 String dir=fileLoad.getDirectory();
	 String name=fileLoad.getFile();
	 if (name==null) { lb1.setText("你没有选定要编辑的文件:"); return;}
	 lb1.setText("编辑文件："+dir+name);
	 try
	 {
	  BufferedReader buff=new BufferedReader(new FileReader(dir+name));
      String line;
      while((line=buff.readLine())!=null) text.append(line+'\n');
      buff.close();
     }
     catch(IOException ee) { lb1.setText(ee.toString()); }			
	}
	else if (e.getSource()==bt2)
	{
	 fileSave.setVisible(true);
	 String dir=fileSave.getDirectory();
	 String name=fileSave.getFile();
	 if (name==null) { lb1.setText("你没有输入(选定)输出文件名!"); return; }	
	 lb1.setText("保存文件的路径为"+dir+"文件名为"+name);
	 try
	 { 
	   FileWriter file=new FileWriter(dir+name); //建立输出文件
       file.write(text.getText()); //将文本框编辑的内容写入输出流
       file.close(); //关闭输出流
     }
     catch(IOException ee) { lb1.setText(ee.toString()); }			
	} 
   }
  public static void main(String args[])
   {
	new File_Dialog();
   }	
}