randomaccessfiledemo.java

学习参考,java基本语法练习,包括一些常用的技巧

//随机文件读写演示
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class RandomAccessFileDemo extends JFrame implements ActionListener
{
	JPanel pnlMain;
	JLabel lblName,lblGender,lblAge,lblAddress;
	JTextField txtName,txtGender,txtAge,txtAddress;
	JButton btnLoad,btnSave;
	JFileChooser fc;
	RandomAccessFile rafUser;
	//构造函数
	public RandomAccessFileDemo()
	{
		super("随机文件读写演示");
		fc=new JFileChooser();
		pnlMain=new JPanel(new GridLayout(5,2));
		lblName=new JLabel("姓名:");
		lblGender=new JLabel("性别:");
		lblAge=new JLabel("年龄:");
		lblAddress=new JLabel("家庭地址:");
		txtName=new JTextField(10);
		txtGender=new JTextField(10);
		txtAge=new JTextField(10);
		txtAddress=new JTextField(10);
		btnLoad=new JButton("读取");
		btnLoad.addActionListener(this);
		btnSave=new JButton("保存");
		btnSave.addActionListener(this);
		pnlMain.add(lblName);
		pnlMain.add(txtName);
		pnlMain.add(lblGender);
		pnlMain.add(txtGender);
		pnlMain.add(lblAge);
		pnlMain.add(txtAge);
		pnlMain.add(lblAddress);
		pnlMain.add(txtAddress);
		pnlMain.add(btnLoad);
		pnlMain.add(btnSave);
		setContentPane(pnlMain);
		setSize(250,150);
		setVisible(true);
	}
	//读取文件方法
	public boolean loadFromFile()
	{
		try
		{
			//构造只读RandomAccessFile对象
			rafUser=new RandomAccessFile("user.txt","r");
			//文件指针定位到文件开始处
			rafUser.seek(0);
			//读取内容到相应组件中
			txtName.setText(rafUser.readLine());
			txtGender.setText(rafUser.readLine());
			txtAge.setText(rafUser.readLine());
			txtAddress.setText(rafUser.readLine());
			//关闭文件
			rafUser.close();
			return true;
		}
		catch(Exception e)
		{
			JOptionPane.showMessageDialog(null,"文件读取失败!");
			//出现异常,返回False值
			return false;
		}
	}
	//保存文件方法
	public boolean saveToFile()
	{
		try
		{
			//构造可读写RandomAccessFile对象
			rafUser=new RandomAccessFile("user.txt","rw");
			//文件指针定位到文件开始处
			rafUser.seek(0);
			//将组件中相应内容写入到文件
			rafUser.writeBytes(txtName.getText()+"\r\n");
			rafUser.writeBytes(txtGender.getText()+"\r\n");
			rafUser.writeBytes(txtAge.getText()+"\r\n");
			rafUser.writeBytes(txtAddress.getText());
			rafUser.close();
			return true;
		}
		catch(Exception e)
		{
			JOptionPane.showMessageDialog(null,"文件保存失败!");
			return false;
		}
	}
	//按钮事件处理
	public void actionPerformed(ActionEvent ae)
	{
		if (ae.getSource()==btnSave)
			if (saveToFile())
				JOptionPane.showMessageDialog(null,"文件保存成功!");
		if (ae.getSource()==btnLoad)
			if (loadFromFile())
				JOptionPane.showMessageDialog(null,"文件读取成功!");
	}
	public static void main(String args[])
	{
		new RandomAccessFileDemo();
	}
}