randomaccessfiledemo.java

来自「里面所含源码是本人平时做程序的一些实例」· Java 代码 · 共 76 行

package notepad;
import javax.swing.*;
import java.io.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class RandomAccessFileDemo extends JFrame implements ActionListener{
	RandomAccessFile raf,r;
	JButton btnOpen,btnSave;
	JPanel pnlMain;
	public RandomAccessFileDemo()
	{
		pnlMain=new JPanel(new FlowLayout());
		btnOpen=new JButton("打开");
		btnSave=new JButton("保存");
		btnOpen.addActionListener(this);
		btnSave.addActionListener(this);
		pnlMain.add(btnSave);
		pnlMain.add(btnOpen);
		setContentPane(pnlMain);
		setVisible(true);
		pack();
		this.setDefaultCloseOperation(2);
	}
	public void actionPerformed(ActionEvent ae)
	{
		if(ae.getSource().equals(btnOpen))
		{
			try
			{
			
				r=new RandomAccessFile("user.txt","r");
				r.seek(6);
				System.out.println(r.readLine());
				System.out.println(r.readLine());
				System.out.println(r.readLine());
				r.close();
				
				
			}
			catch(Exception e)
			{
				JOptionPane.showMessageDialog(null, "文件打开失败");
				e.printStackTrace();
			}
		}
		if(ae.getSource()==btnSave)
		{
			try{
				raf=new RandomAccessFile("user.txt","rw");
				raf.seek(raf.length());
				raf.writeBytes("zhangsan\r\n");
				raf.writeBytes("nan\r\n");
				raf.writeBytes("15\r\n");
				raf.writeBytes("shiyuhsao\r\n");
				raf.writeBytes("nv\r\n");
				raf.writeBytes("18\r\n");
				raf.close();
		
			}
			catch(Exception e){
				JOptionPane.showMessageDialog(null, "文件保存失败");
				e.printStackTrace();
			}
		}
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
			new RandomAccessFileDemo();
		
	}

}