fileio.java

jdbc书

import java.awt.Font;
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.File;
import java.io.BufferedReader;
import java.io.InputStreamReader;

class FileIO extends JFrame
		 implements ActionListener {

   JLabel text, clicked;
   JButton button, clickButton;
   JPanel panel;
   JTextField textField;

   FileIO(){ //Begin Constructor
     setFont(new Font("Helvetica", Font.PLAIN, 14));
     text = new JLabel("Text to save to file:");
     clicked = new JLabel("Text retrieved from file:");

     button = new JButton("Click Me");
     button.addActionListener(this);

     clickButton = new JButton("Click Again");
     clickButton.addActionListener(this);

     textField = new JTextField(20);

     panel = new JPanel();
     panel.setLayout(new BorderLayout());
     panel.setBackground(Color.white);
     getContentPane().add(panel);
     panel.add("North", text);
     panel.add("Center", textField);
     panel.add("South", button);
   } //End Constructor

   public void actionPerformed(ActionEvent event){
     Object source = event.getSource();
     if(source == button){
        JLabel label = new JLabel();

	try{
//Write to file
		String text = textField.getText();
                byte b[] = text.getBytes();

		File outputFile = new File(File.separatorChar + "home" + File.separatorChar
+ "monicap" + File.separatorChar + "text.txt");
		FileOutputStream out = new FileOutputStream(outputFile);
		out.write(b);
		out.close();
//Read from file
                File inputFile = new File(File.separatorChar + "home" + File.separatorChar +
"monicap" + File.separatorChar + "text2.txt");
                FileInputStream in = new FileInputStream(inputFile);
		byte bt[] = new byte[(int)inputFile.length()];
		int i;
		i = in.read(bt);
		String s = new String(bt);
                label.setText(s);
                in.close();
	}catch(java.io.IOException e){
		System.out.println(e.toString());
	}
//Display text read from file
                panel.removeAll();
                panel.add("North", clicked); 
                panel.add("Center", label);
 		panel.add("South", clickButton);
                panel.validate();
                panel.repaint();
        }

	if(source == clickButton){
                panel.removeAll();
                panel.add("North", text);
		textField.setText("");
		panel.add("Center", textField);
                panel.add("South", button);
                panel.validate();
                panel.repaint();
	}
   }

   public static void main(String[] args){

        BufferedReader buffy = new BufferedReader(
                                   new InputStreamReader(System.in));
        try {
            System.setSecurityManager(
                        new PasswordSecurityManager("pwd", buffy));
        } catch (SecurityException se) {
            System.err.println("SecurityManager already set!");
        }

        try{
            UIManager.setLookAndFeel(
              UIManager.getCrossPlatformLookAndFeelClassName());
        }catch (Exception e) {
           System.err.println("Couldn't use the cross-platform"
              + "look and feel: " + e);
        }

        JFrame frame = new FileIO();
	frame.setTitle("Example");
        WindowListener l = new WindowAdapter() {
                public void windowClosing(WindowEvent e) {
                        System.exit(0);
                }
        };

        frame.addWindowListener(l);
        frame.pack();
        frame.setVisible(true);
    }
}