monitorupdate.java

java做的文件监控器,文件被修改了就会有提示

import javax.swing.*;
import java.awt.*;
import java.io.*;

public class MonitorUpdate extends JFrame implements Runnable
{
	BufferedReader br;
	String content;
	public MonitorUpdate() throws Exception
	{
		br=new BufferedReader(new FileReader("1.txt"));
		
		String tmp=null;
		while((tmp=br.readLine())!=null)
			content=content+tmp;
		
		br.close();
		this.setBounds(100,100,200,100);
		this.setVisible(true);
		new Thread(this).start();
	}
	public void run()
	{
		while(true)
		{
		
			try 
		    {
		    	br=new BufferedReader(new FileReader("1.txt"));
		    
		    	

		    	String tmp=null;
				String r=null;
				while((tmp=br.readLine())!=null)
					r=r+tmp;
				br.close();
				if(!content.equals(r))
					JOptionPane.showMessageDialog(this,"File is updated!");
	
		    	Thread.sleep(5000);
		    	
		    }
		    catch (Exception ex) 
		    {
		    	ex.printStackTrace();
		    }
		    
			
		}
	}
	
	public static void main(String [] args) throws Exception
	{
		new MonitorUpdate ();
	
		
	}
}