SwingFileDownloadHTTP.java

package net.codejava.swing.download;

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JProgressBar;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

import net.codejava.swing.JFilePicker;

/**
 * A Swing application that downloads file from an HTTP server.
 * @author www.codejava.net
 *
 */
public class SwingFileDownloadHTTP extends JFrame implements
		PropertyChangeListener {
	private JLabel labelURL = new JLabel("Download URL: ");
	private JTextField fieldURL = new JTextField(30);

	private JFilePicker filePicker = new JFilePicker("Save in directory: ",
			"Browse...");

	private JButton buttonDownload = new JButton("Download");

	private JLabel labelFileName = new JLabel("File name: ");
	private JTextField fieldFileName = new JTextField(20);

	private JLabel labelFileSize = new JLabel("File size (bytes): ");
	private JTextField fieldFileSize = new JTextField(20);

	private JLabel labelProgress = new JLabel("Progress:");
	private JProgressBar progressBar = new JProgressBar(0, 100);

	public SwingFileDownloadHTTP() {
		super("Swing File Download from HTTP server");

		// set up layout
		setLayout(new GridBagLayout());
		GridBagConstraints constraints = new GridBagConstraints();
		constraints.anchor = GridBagConstraints.WEST;
		constraints.insets = new Insets(5, 5, 5, 5);

		// set up components
		filePicker.setMode(JFilePicker.MODE_SAVE);
		filePicker.getFileChooser().setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);

		buttonDownload.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent event) {
				buttonDownloadActionPerformed(event);
			}
		});

		fieldFileName.setEditable(false);
		fieldFileSize.setEditable(false);

		progressBar.setPreferredSize(new Dimension(200, 30));
		progressBar.setStringPainted(true);

		// add components to the frame
		constraints.gridx = 0;
		constraints.gridy = 0;
		add(labelURL, constraints);

		constraints.gridx = 1;
		constraints.fill = GridBagConstraints.HORIZONTAL;
		constraints.weightx = 1.0;
		add(fieldURL, constraints);

		constraints.gridx = 0;
		constraints.gridy = 1;
		constraints.weightx = 0.0;
		constraints.gridwidth = 2;
		constraints.fill = GridBagConstraints.NONE;
		add(filePicker, constraints);

		constraints.gridy = 2;
		constraints.anchor = GridBagConstraints.CENTER;
		add(buttonDownload, constraints);

		constraints.gridx = 0;
		constraints.gridy = 3;
		constraints.gridwidth = 1;
		constraints.anchor = GridBagConstraints.WEST;
		add(labelFileName, constraints);

		constraints.gridx = 1;
		add(fieldFileName, constraints);

		constraints.gridy = 4;
		constraints.gridx = 0;
		add(labelFileSize, constraints);

		constraints.gridx = 1;
		add(fieldFileSize, constraints);

		constraints.gridx = 0;
		constraints.gridy = 5;
		constraints.gridwidth = 1;
		constraints.anchor = GridBagConstraints.WEST;
		add(labelProgress, constraints);

		constraints.gridx = 1;
		constraints.weightx = 1.0;
		constraints.fill = GridBagConstraints.HORIZONTAL;
		add(progressBar, constraints);

		pack();
		setLocationRelativeTo(null);	// center on screen
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

	/**
	 * handle click event of the Upload button
	 */
	private void buttonDownloadActionPerformed(ActionEvent event) {
		String downloadURL = fieldURL.getText();
		String saveDir = filePicker.getSelectedFilePath();

		// validate input first
		if (downloadURL.equals("")) {
			JOptionPane.showMessageDialog(this, "Please enter download URL!",
					"Error", JOptionPane.ERROR_MESSAGE);
			fieldURL.requestFocus();
			return;
		}

		if (saveDir.equals("")) {
			JOptionPane.showMessageDialog(this,
					"Please choose a directory save file!", "Error",
					JOptionPane.ERROR_MESSAGE);
			return;
		}

		try {
			progressBar.setValue(0);

			DownloadTask task = new DownloadTask(this, downloadURL, saveDir);
			task.addPropertyChangeListener(this);
			task.execute();
		} catch (Exception ex) {
			JOptionPane.showMessageDialog(this,
					"Error executing upload task: " + ex.getMessage(), "Error",
					JOptionPane.ERROR_MESSAGE);
		}
	}

	void setFileInfo(String name, int size) {
		fieldFileName.setText(name);
		fieldFileSize.setText(String.valueOf(size));
	}

	/**
	 * Update the progress bar's state whenever the progress of download changes.
	 */
	@Override
	public void propertyChange(PropertyChangeEvent evt) {
		if (evt.getPropertyName().equals("progress")) {
			int progress = (Integer) evt.getNewValue();
			progressBar.setValue(progress);
		}
	}

	/**
	 * Launch the application
	 */
	public static void main(String[] args) {
		try {
			// set look and feel to system dependent
			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		} catch (Exception ex) {
			ex.printStackTrace();
		}

		SwingUtilities.invokeLater(new Runnable() {
			@Override
			public void run() {
				new SwingFileDownloadHTTP().setVisible(true);
			}
		});
	}
}