Download Manager - Language Basics Source Code in Java

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Home » Java Home » Language Basics Home » Download Manager

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Title	Download Manager
Author	Sagar
Author Email	sag_with_comp
Description	This is Very Useful tool for Inetnet users. Create & enjoy it. Contact Me If U Like it.
Category	Java » Language Basics
Hits	428665
Code	Select and Copy the Code
/** * Download Manager * * Auther: Sagar Nangare * Email: sag_with_comp@yahoo.co.in * * Save-Listing1 as>Download.java, Listing 2 as>DownloadManager.java, Listing 3 as>DownloadsTableModel.java,Listing 4 as>ProgressRenderer.java. Then Compile like>javac DownloadManager.java DownloadsTableModel.java ProgressRenderer.java Download.java & then > javaw DownloadManager / listing 1 import java.io.; import java.net.; import java.util.; // This class downloads a file from a URL. class Download extends Observable implements Runnable { // Max size of download buffer. private static final int MAX_BUFFER_SIZE = 1024; // These are the status names. public static final String STATUSES[] = {"Downloading", "Paused", "Complete", "Cancelled", "Error"}; // These are the status codes. public static final int DOWNLOADING = 0; public static final int PAUSED = 1; public static final int COMPLETE = 2; public static final int CANCELLED = 3; public static final int ERROR = 4; private URL url; // download URL private int size; // size of download in bytes private int downloaded; // number of bytes downloaded private int status; // current status of download // Constructor for Download. public Download(URL url) { this.url = url; size = -1; downloaded = 0; status = DOWNLOADING; // Begin the download. download(); } // Get this download's URL. public String getUrl() { return url.toString(); } // Get this download's size. public int getSize() { return size; } // Get this download's progress. public float getProgress() { return ((float) downloaded / size) * 100; } // Get this download's status. public int getStatus() { return status; } // Pause this download. public void pause() { status = PAUSED; stateChanged(); } // Resume this download. public void resume() { status = DOWNLOADING; stateChanged(); download(); } // Cancel this download. public void cancel() { status = CANCELLED; stateChanged(); } // Mark this download as having an error. private void error() { status = ERROR; stateChanged(); } // Start or resume downloading. private void download() { Thread thread = new Thread(this); thread.start(); } // Get file name portion of URL. private String getFileName(URL url) { String fileName = url.getFile(); return fileName.substring(fileName.lastIndexOf('/') + 1); } // Download file. public void run() { RandomAccessFile file = null; InputStream stream = null; try { // Open connection to URL. HttpURLConnection connection = (HttpURLConnection) url.openConnection(); // Specify what portion of file to download. connection.setRequestProperty("Range", "bytes=" + downloaded + "-"); // Connect to server. connection.connect(); // Make sure response code is in the 200 range. if (connection.getResponseCode() / 100 != 2) { error(); } // Check for valid content length. int contentLength = connection.getContentLength(); if (contentLength < 1) { error(); } /* Set the size for this download if it hasn't been already set. / if (size == -1) { size = contentLength; stateChanged(); } // Open file and seek to the end of it. file = new RandomAccessFile(getFileName(url), "rw"); file.seek(downloaded); stream = connection.getInputStream(); while (status == DOWNLOADING) { / Size buffer according to how much of the file is left to download. / byte buffer[]; if (size - downloaded > MAX_BUFFER_SIZE) { buffer = new byte[MAX_BUFFER_SIZE]; } else { buffer = new byte[size - downloaded]; } // Read from server into buffer. int read = stream.read(buffer); if (read == -1) break; // Write buffer to file. file.write(buffer, 0, read); downloaded += read; stateChanged(); } / Change status to complete if this point was reached because downloading has finished. / if (status == DOWNLOADING) { status = COMPLETE; stateChanged(); } } catch (Exception e) { error(); } finally { // Close file. if (file != null) { try { file.close(); } catch (Exception e) {} } // Close connection to server. if (stream != null) { try { stream.close(); } catch (Exception e) {} } } } // Notify observers that this download's status has changed. private void stateChanged() { setChanged(); notifyObservers(); } } listing 2 import java.awt.; import java.awt.event.; import java.net.; import java.util.; import javax.swing.; import javax.swing.event.; // The Download Manager. public class DownloadManager extends JFrame implements Observer { // Add download text field. private JTextField addTextField; // Download table's data model. private DownloadsTableModel tableModel; // Table showing downloads. private JTable table; // These are the buttons for managing the selected download. private JButton pauseButton, resumeButton; private JButton cancelButton, clearButton; // Currently selected download. private Download selectedDownload; // Flag for whether or not table selection is being cleared. private boolean clearing; // Constructor for Download Manager. public DownloadManager() { // Set application title. setTitle("Download Manager"); // Set window size. setSize(640, 480); // Handle window closing events. addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { actionExit(); } }); // Set up file menu. JMenuBar menuBar = new JMenuBar(); JMenu fileMenu = new JMenu("File"); fileMenu.setMnemonic(KeyEvent.VK_F); JMenuItem fileExitMenuItem = new JMenuItem("Exit", KeyEvent.VK_X); fileExitMenuItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionExit(); } }); fileMenu.add(fileExitMenuItem); menuBar.add(fileMenu); setJMenuBar(menuBar); // Set up add panel. JPanel addPanel = new JPanel(); addTextField = new JTextField(30); addPanel.add(addTextField); JButton addButton = new JButton("Add Download"); addButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionAdd(); } }); addPanel.add(addButton); // Set up Downloads table. tableModel = new DownloadsTableModel(); table = new JTable(tableModel); table.getSelectionModel().addListSelectionListener(new ListSelectionListener() { public void valueChanged(ListSelectionEvent e) { tableSelectionChanged(); } }); // Allow only one row at a time to be selected. table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); // Set up ProgressBar as renderer for progress column. ProgressRenderer renderer = new ProgressRenderer(0, 100); renderer.setStringPainted(true); // show progress text table.setDefaultRenderer(JProgressBar.class, renderer); // Set table's row height large enough to fit JProgressBar. table.setRowHeight( (int) renderer.getPreferredSize().getHeight()); // Set up downloads panel. JPanel downloadsPanel = new JPanel(); downloadsPanel.setBorder( BorderFactory.createTitledBorder("Downloads")); downloadsPanel.setLayout(new BorderLayout()); downloadsPanel.add(new JScrollPane(table), BorderLayout.CENTER); // Set up buttons panel. JPanel buttonsPanel = new JPanel(); pauseButton = new JButton("Pause"); pauseButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionPause(); } }); pauseButton.setEnabled(false); buttonsPanel.add(pauseButton); resumeButton = new JButton("Resume"); resumeButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionResume(); } }); resumeButton.setEnabled(false); buttonsPanel.add(resumeButton); cancelButton = new JButton("Cancel"); cancelButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionCancel(); } }); cancelButton.setEnabled(false); buttonsPanel.add(cancelButton); clearButton = new JButton("Clear"); clearButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { actionClear(); } }); clearButton.setEnabled(false); buttonsPanel.add(clearButton); // Add panels to display. getContentPane().setLayout(new BorderLayout()); getContentPane().add(addPanel, BorderLayout.NORTH); getContentPane().add(downloadsPanel, BorderLayout.CENTER); getContentPane().add(buttonsPanel, BorderLayout.SOUTH); } // Exit this program. private void actionExit() { System.exit(0); } // Add a new download. private void actionAdd() { URL verifiedUrl = verifyUrl(addTextField.getText()); if (verifiedUrl != null) { tableModel.addDownload(new Download(verifiedUrl)); addTextField.setText(""); // reset add text field } else { JOptionPane.showMessageDialog(this, "Invalid Download URL", "Error", JOptionPane.ERROR_MESSAGE); } } // Verify download URL. private URL verifyUrl(String url) { // Only allow HTTP URLs. if (!url.toLowerCase().startsWith("http://")) return null; // Verify format of URL. URL verifiedUrl = null; try { verifiedUrl = new URL(url); } catch (Exception e) { return null; } // Make sure URL specifies a file. if (verifiedUrl.getFile().length() < 2) return null; return verifiedUrl; } // Called when table row selection changes. private void tableSelectionChanged() { / Unregister from receiving notifications from the last selected download. / if (selectedDownload != null) selectedDownload.deleteObserver(DownloadManager.this); / If not in the middle of clearing a download, set the selected download and register to receive notifications from it. / if (!clearing && table.getSelectedRow() > -1) { selectedDownload = tableModel.getDownload(table.getSelectedRow()); selectedDownload.addObserver(DownloadManager.this); updateButtons(); } } // Pause the selected download. private void actionPause() { selectedDownload.pause(); updateButtons(); } // Resume the selected download. private void actionResume() { selectedDownload.resume(); updateButtons(); } // Cancel the selected download. private void actionCancel() { selectedDownload.cancel(); updateButtons(); } // Clear the selected download. private void actionClear() { clearing = true; tableModel.clearDownload(table.getSelectedRow()); clearing = false; selectedDownload = null; updateButtons(); } / Update each button's state based off of the currently selected download's status. / private void updateButtons() { if (selectedDownload != null) { int status = selectedDownload.getStatus(); switch (status) { case Download.DOWNLOADING: pauseButton.setEnabled(true); resumeButton.setEnabled(false); cancelButton.setEnabled(true); clearButton.setEnabled(false); break; case Download.PAUSED: pauseButton.setEnabled(false); resumeButton.setEnabled(true); cancelButton.setEnabled(true); clearButton.setEnabled(false); break; case Download.ERROR: pauseButton.setEnabled(false); resumeButton.setEnabled(true); cancelButton.setEnabled(false); clearButton.setEnabled(true); break; default: // COMPLETE or CANCELLED pauseButton.setEnabled(false); resumeButton.setEnabled(false); cancelButton.setEnabled(false); clearButton.setEnabled(true); } } else { // No download is selected in table. pauseButton.setEnabled(false); resumeButton.setEnabled(false); cancelButton.setEnabled(false); clearButton.setEnabled(false); } } / Update is called when a Download notifies its observers of any changes. / public void update(Observable o, Object arg) { // Update buttons if the selected download has changed. if (selectedDownload != null && selectedDownload.equals(o)) updateButtons(); } // Run the Download Manager. public static void main(String[] args) { DownloadManager manager = new DownloadManager(); manager.setVisible(true); } } listing 3 import java.util.; import javax.swing.; import javax.swing.table.; // This class manages the download table's data. class DownloadsTableModel extends AbstractTableModel implements Observer { // These are the names for the table's columns. private static final String[] columnNames = {"URL", "Size", "Progress", "Status"}; // These are the classes for each column's values. private static final Class[] columnClasses = {String.class, String.class, JProgressBar.class, String.class}; // The table's list of downloads. private ArrayList<Download> downloadList = new ArrayList<Download>(); // Add a new download to the table. public void addDownload(Download download) { // Register to be notified when the download changes. download.addObserver(this); downloadList.add(download); // Fire table row insertion notification to table. fireTableRowsInserted(getRowCount() - 1, getRowCount() - 1); } // Get a download for the specified row. public Download getDownload(int row) { return (Download) downloadList.get(row); } // Remove a download from the list. public void clearDownload(int row) { downloadList.remove(row); // Fire table row deletion notification to table. fireTableRowsDeleted(row, row); } // Get table's column count. public int getColumnCount() { return columnNames.length; } // Get a column's name. public String getColumnName(int col) { return columnNames[col]; } // Get a column's class. public Class getColumnClass(int col) { return columnClasses[col]; } // Get table's row count. public int getRowCount() { return downloadList.size(); } // Get value for a specific row and column combination. public Object getValueAt(int row, int col) { Download download = downloadList.get(row); switch (col) { case 0: // URL return download.getUrl(); case 1: // Size int size = download.getSize(); return (size == -1) ? "" : Integer.toString(size); case 2: // Progress return new Float(download.getProgress()); case 3: // Status return Download.STATUSES[download.getStatus()]; } return ""; } /* Update is called when a Download notifies its observers of any changes / public void update(Observable o, Object arg) { int index = downloadList.indexOf(o); // Fire table row update notification to table. fireTableRowsUpdated(index, index); } } listing 4 import java.awt.; import javax.swing.; import javax.swing.table.; // This class renders a JProgressBar in a table cell. class ProgressRenderer extends JProgressBar implements TableCellRenderer { // Constructor for ProgressRenderer. public ProgressRenderer(int min, int max) { super(min, max); } /* Returns this JProgressBar as the renderer for the given table cell. */ public Component getTableCellRendererComponent( JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) { // Set JProgressBar's percent complete value. setValue((int) ((Float) value).floatValue()); return this; } }

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