Sample project for Java Swing HTTP File Downloader

Author: namhaminh

Compile instructions.txt

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+javac -d build\classes -cp src src\net\codejava\swing\download\SwingFileDownloadHTTP.java
+jar cfev SwingFileDownloadHTTP.jar net.codejava.swing.download.SwingFileDownloadHTTP -C build\classes .

SwingFileDownloadHTTP.jar

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+package net.codejava.swing;
+
+import java.io.File;
+import javax.swing.filechooser.FileFilter;
+
+public class FileTypeFilter extends FileFilter {
+
+	private String extension;
+	private String description;
+	
+	public FileTypeFilter(String extension, String description) {
+		this.extension = extension;
+		this.description = description;
+	}
+	
+	@Override
+	public boolean accept(File file) {
+		if (file.isDirectory()) {
+			return true;
+		}
+		return file.getName().toLowerCase().endsWith(extension);
+	}
+	
+	public String getDescription() {
+		return description + String.format(" (*%s)", extension);
+	}
+}

build/classes/net/codejava/swing/FileTypeFilter.class

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+package net.codejava.swing;
+
+import java.awt.FlowLayout;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+
+import javax.swing.JButton;
+import javax.swing.JFileChooser;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+
+public class JFilePicker extends JPanel {
+	private String textFieldLabel;
+	private String buttonLabel;
+	
+	private JLabel label;
+	private JTextField textField;
+	private JButton button;
+	
+	private JFileChooser fileChooser;
+	
+	private int mode;
+	public static final int MODE_OPEN = 1;
+	public static final int MODE_SAVE = 2;
+	
+	public JFilePicker(String textFieldLabel, String buttonLabel) {
+		this.textFieldLabel = textFieldLabel;
+		this.buttonLabel = buttonLabel;
+		
+		fileChooser = new JFileChooser();
+		
+		setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
+
+		// creates the GUI
+		label = new JLabel(textFieldLabel);
+		
+		textField = new JTextField(30);
+		button = new JButton(buttonLabel);
+		
+		button.addActionListener(new ActionListener() {
+			@Override
+			public void actionPerformed(ActionEvent evt) {
+				buttonActionPerformed(evt);				
+			}
+		});
+		
+		add(label);
+		add(textField);
+		add(button);
+		
+	}
+	
+	private void buttonActionPerformed(ActionEvent evt) {
+		if (mode == MODE_OPEN) {
+			if (fileChooser.showOpenDialog(this) == JFileChooser.APPROVE_OPTION) {
+				textField.setText(fileChooser.getSelectedFile().getAbsolutePath());
+			}
+		} else if (mode == MODE_SAVE) {
+			if (fileChooser.showSaveDialog(this) == JFileChooser.APPROVE_OPTION) {
+				textField.setText(fileChooser.getSelectedFile().getAbsolutePath());
+			}
+		}
+	}
+
+	public void addFileTypeFilter(String extension, String description) {
+		FileTypeFilter filter = new FileTypeFilter(extension, description);
+		fileChooser.addChoosableFileFilter(filter);
+	}
+	
+	public void setMode(int mode) {
+		this.mode = mode;
+	}
+	
+	public String getSelectedFilePath() {
+		return textField.getText();
+	}
+	
+	public JFileChooser getFileChooser() {
+		return this.fileChooser;
+	}
+}

build/classes/net/codejava/swing/JFilePicker$1.class

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+package net.codejava.swing.download;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import javax.swing.JOptionPane;
+import javax.swing.SwingWorker;
+
+/**
+ * Execute file download in a background thread and update the progress. 
+ * @author www.codejava.net
+ *
+ */
+public class DownloadTask extends SwingWorker<Void, Void> {
+	private static final int BUFFER_SIZE = 4096;	
+	private String downloadURL;
+	private String saveDirectory;
+	private SwingFileDownloadHTTP gui;
+	
+	public DownloadTask(SwingFileDownloadHTTP gui, String downloadURL, String saveDirectory) {
+		this.gui = gui;
+		this.downloadURL = downloadURL;
+		this.saveDirectory = saveDirectory;
+	}
+	
+	/**
+	 * Executed in background thread
+	 */	
+	@Override
+	protected Void doInBackground() throws Exception {
+		try {
+			HTTPDownloadUtil util = new HTTPDownloadUtil();
+			util.downloadFile(downloadURL);
+			
+			// set file information on the GUI
+			gui.setFileInfo(util.getFileName(), util.getContentLength());
+			
+			String saveFilePath = saveDirectory + File.separator + util.getFileName();
+
+			InputStream inputStream = util.getInputStream();
+			// opens an output stream to save into file
+			FileOutputStream outputStream = new FileOutputStream(saveFilePath);
+
+			byte[] buffer = new byte[BUFFER_SIZE];
+			int bytesRead = -1;
+			long totalBytesRead = 0;
+			int percentCompleted = 0;
+			long fileSize = util.getContentLength();
+
+			while ((bytesRead = inputStream.read(buffer)) != -1) {
+				outputStream.write(buffer, 0, bytesRead);
+				totalBytesRead += bytesRead;
+				percentCompleted = (int) (totalBytesRead * 100 / fileSize);
+
+				setProgress(percentCompleted);			
+			}
+
+			outputStream.close();
+
+			util.disconnect();
+		} catch (IOException ex) {
+			JOptionPane.showMessageDialog(gui, "Error downloading file: " + ex.getMessage(),
+					"Error", JOptionPane.ERROR_MESSAGE);			
+			ex.printStackTrace();
+			setProgress(0);
+			cancel(true);			
+		}
+		return null;
+	}
+
+	/**
+	 * Executed in Swing's event dispatching thread
+	 */
+	@Override
+	protected void done() {
+		if (!isCancelled()) {
+			JOptionPane.showMessageDialog(gui,
+					"File has been downloaded successfully!", "Message",
+					JOptionPane.INFORMATION_MESSAGE);
+		}
+	}	
+}

build/classes/net/codejava/swing/JFilePicker.class

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+package net.codejava.swing.download;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+/**
+ * A utility that downloads a file from a URL.
+ * 
+ * @author www.codejava.net
+ * 
+ */
+public class HTTPDownloadUtil {
+
+	private HttpURLConnection httpConn;
+
+	/**
+	 * hold input stream of HttpURLConnection
+	 */
+	private InputStream inputStream;
+
+	private String fileName;
+	private int contentLength;
+
+	/**
+	 * Downloads a file from a URL
+	 * 
+	 * @param fileURL
+	 *            HTTP URL of the file to be downloaded
+	 * @throws IOException
+	 */
+	public void downloadFile(String fileURL) throws IOException {
+		URL url = new URL(fileURL);
+		httpConn = (HttpURLConnection) url.openConnection();
+		int responseCode = httpConn.getResponseCode();
+
+		// always check HTTP response code first
+		if (responseCode == HttpURLConnection.HTTP_OK) {
+			String disposition = httpConn.getHeaderField("Content-Disposition");
+			String contentType = httpConn.getContentType();
+			contentLength = httpConn.getContentLength();
+
+			if (disposition != null) {
+				// extracts file name from header field
+				int index = disposition.indexOf("filename=");
+				if (index > 0) {
+					fileName = disposition.substring(index + 10,
+							disposition.length() - 1);
+				}
+			} else {
+				// extracts file name from URL
+				fileName = fileURL.substring(fileURL.lastIndexOf("/") + 1,
+						fileURL.length());
+			}
+
+			// output for debugging purpose only
+			System.out.println("Content-Type = " + contentType);
+			System.out.println("Content-Disposition = " + disposition);
+			System.out.println("Content-Length = " + contentLength);
+			System.out.println("fileName = " + fileName);
+
+			// opens input stream from the HTTP connection
+			inputStream = httpConn.getInputStream();
+
+		} else {
+			throw new IOException(
+					"No file to download. Server replied HTTP code: "
+							+ responseCode);
+		}
+	}
+
+	public void disconnect() throws IOException {
+		inputStream.close();
+		httpConn.disconnect();
+	}
+
+	public String getFileName() {
+		return this.fileName;
+	}
+
+	public int getContentLength() {
+		return this.contentLength;
+	}
+
+	public InputStream getInputStream() {
+		return this.inputStream;
+	}
+}