example8_3.java

书中的例题

/* 文件的读取和写入 */
import java.io.*;
import java.awt.*;
import java.awt.event.*;

class  Win extends Frame implements ActionListener
{
 FileReader      r_file;
 FileWriter      w_file;
 BufferedReader  buf_reader;
 BufferedWriter  buf_writer;
 TextArea        txt;
 Button          btn1,btn2;
 Panel           p;
 Win()
 {
  setSize(200,200);
  setVisible(true);
  txt=new TextArea(10,10);
  btn1=new Button("Read");
  btn2=new Button("Write");
  btn1.addActionListener(this);
  btn2.addActionListener(this);
  p=new Panel();
  add(txt,"Center");
  add(p,"South"); 
  p.setLayout(new FlowLayout());
  p.add(btn1);
  p.add(btn2);
  validate();
  addWindowListener(new WindowAdapter() {
    public void windowClosing(WindowEvent e) {
         System.exit(0);
      }
  });
 }
 public void actionPerformed(ActionEvent e)
  {
     if (e.getSource()==btn1)
     { readFile(); }

     if (e.getSource()==btn2)
     {  writeFile(); }
   }
   //读取文件
  public void readFile()
  {
        String s;
	try{
		File f=new File("D:/jtest/","Test.txt");
		r_file=new FileReader(f);
        buf_reader=new BufferedReader(r_file);
	   }
    catch(IOException ef){ System.out.println(ef); }
	try{
		while ((s=buf_reader.readLine())!=null)
		    {txt.append(s+'\n');}
       }
    catch(IOException er){ System.out.println(er);  }
  }
  //写入文件
  public void writeFile()
  {
	try{  
          w_file=new FileWriter("Hello.txt");
          buf_writer=new BufferedWriter(w_file);
          String str=txt.getText();
          buf_writer.write(str,0,str.length());
          buf_writer.flush();
	   }
   catch(IOException ew){ System.out.println(ew); }
  }
}

public class Example8_3
{
	public static void main(String[] args) 
	{
		Win w=new Win();
	}
}