java - progress bar и скачайте

Question

Код ниже делает именно то, что мне нужно, чтобы ожидать одно. Мне просто нужно сделать эту загрузку еще несколькими разными URL-адресами (изображениями), к сожалению, я понятия не имел, как это сделать. Если бы кто-нибудь мог помочь мне решить это, я был бы так благодарен.

import java.io.BufferedOutputStream; 
import java.io.FileNotFoundException; 
import java.io.IOException; 
import java.net.HttpURLConnection; 
import java.net.URL; 

import javax.swing.JFrame; 
import javax.swing.JProgressBar; 
import javax.swing.SwingUtilities; 
import javax.swing.WindowConstants; 

public class Progressbar { 

    public static void main(String[] args) { 

    final JProgressBar jProgressBar = new JProgressBar(); 
    jProgressBar.setMaximum(100000); 
    JFrame frame = new JFrame(); 
    frame.setContentPane(jProgressBar); 
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); 
    frame.setSize(300, 70); 
    frame.setVisible(true); 
    Runnable updatethread = new Runnable() { 
     public void run() { 
     try { 
      URL url = new URL("http://www.drgarbage.com/img/howto/cfgf-tutorial/createcfg.png"); 
      HttpURLConnection httpConnection = (HttpURLConnection) (url.openConnection());       
      long completeFileSize = httpConnection.getContentLength(); 
      java.io.BufferedInputStream in = new  java.io.BufferedInputStream(httpConnection.getInputStream()); 
      java.io.FileOutputStream fos = new java.io.FileOutputStream("picture.png"); 
      java.io.BufferedOutputStream bout = new BufferedOutputStream(fos, 1024);      
      byte[] data = new byte[1024]; 
      long downloadedFileSize = 0; 
      int x = 0; 
      while ((x = in.read(data, 0, 1024)) >= 0) { 
      downloadedFileSize += x; 

      // calculate progress 
      final int currentProgress = (int) ((((double)downloadedFileSize)/((double)completeFileSize)) * 100000d); 

      // update progress bar 
      SwingUtilities.invokeLater(new Runnable() { 

       @Override 
       public void run() { 
       ProgressBar.setValue(currentProgress); 
       } 
      }); 
      bout.write(data, 0, x); 
      } 
      bout.close(); 
      in.close(); 
     } catch (FileNotFoundException e) { 
     } catch (IOException e) { 
     } 
     } 
    }; 
    new Thread(updatethread). 

    start(); 
    } 
} 

Answer 1

Вот быстрое решение, основанное на https://docs.oracle.com/javase/tutorial/uiswing/examples/components/ProgressBarDemoProject/src/components/ProgressBarDemo.java

Расчет прогресс использует немного обмана в том, что он предполагает, что все файлы примерно одинакового размера. Было бы правильнее предварительно отбирать все размеры файлов, а затем делать расчеты с полным количеством.

Редактировать: Я добавил дополнительный индикатор выполнения, отображающий текущую загрузку файла на основе решения, указанного в https://stackoverflow.com/a/8917565/3469592. Я не уверен, это хорошая практика. Критика и предложения по улучшению приветствуются.

Предупреждение: Код искусственно замедляется, чтобы облегчить просмотр. Удалите часть Thread.sleep(200), если вы действительно хотите использовать это!

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import java.io.FileNotFoundException; 
import java.io.IOException; 


import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import java.beans.*; 

public class ProgressBarDemo extends JPanel 
          implements ActionListener, 
             PropertyChangeListener { 

    private JProgressBar overallProgressBar; 
    private JProgressBar currentProgressBar; 
    private JButton startButton; 
    private JTextArea taskOutput; 
    private Task task; 

    class Task extends SwingWorker<Void, Integer> { 

    private final JProgressBar currentProgressBar; 

    private Task(JProgressBar progressBar) { 
     currentProgressBar = progressBar; 
    } 

    private void download(String urlString, int fileNumber, int total) { 
     java.io.InputStream in = null; 
     java.io.OutputStream out = null; 

     try { 
     taskOutput.append("Downloading file " + fileNumber + "..."); 

     java.net.URL url = new java.net.URL(urlString); 

     java.net.HttpURLConnection httpConnection = (java.net.HttpURLConnection) (url.openConnection()); 

     long completeFileSize = httpConnection.getContentLength(); 
     in = httpConnection.getInputStream(); 
     out = new java.io.FileOutputStream("picture"+fileNumber+".png"); 

     final byte[] data = new byte[1024]; 
     long downloadedFileSize = 0; 
     int count; 
     while ((count = in.read(data, 0, 1024)) != -1) { 
      // -------------------------- 
      // TODO: Make downloads slower so you can watch things better, do not use in production code! 
      try { 
      Thread.sleep(200); 
      } catch (InterruptedException ignore) {} 
      // -------------------------- 

      downloadedFileSize += count; 

      /* calculate progress (cheap variant, we assume that files are roughly the same size), another, more proper, way would be to prefetch all file sizes and give actual progress */ 
      final int currentProgress = (int) (((double)downloadedFileSize)/((double)completeFileSize) * 100d); 
      final int scaledCurrentProgress = currentProgress/total; 
      final int overallProgress = (int) (((double)fileNumber/(double)total) * 100d); 
      /* notifications of progress */ 
      setProgress(Math.min(scaledCurrentProgress + overallProgress,100)); 
      publish(Math.min(currentProgress,100)); 
      /* save downloaded data */   
      out.write(data, 0, count); 
     } 

     taskOutput.append("done!\n");   
     } catch (FileNotFoundException e) { 
     taskOutput.append("File not found: " + e); 
     } catch (IOException e) { 
     taskOutput.append("IO exception: " + e); 
     } catch (Exception e) { 
     taskOutput.append("Something went wrong: " + e); 
     } finally { 
     try { 
      if (in != null) { 
      in.close(); 
      } 
      if (out != null) { 
      out.close(); 
      } 
     } catch (IOException e) { 
      taskOutput.append("IO exception: " + e); 
     } 
     } 
    } 

    /* 
    * Main task. Executed in background thread. 
    */ 
    @Override 
    public Void doInBackground() { 
     // TODO: Probably this data would be given to the class in the constructor 
     java.util.List<String> urlStrings = java.util.Arrays.asList(
              "http://imgs.xkcd.com/comics/tamagotchi_hive.png ", 
              "http://imgs.xkcd.com/comics/solar_system_questions.png ", 
              "http://imgs.xkcd.com/comics/90s_kid.png", 
              "http://imgs.xkcd.com/comics/xkcd_phone_3.png", 
              "http://imgs.xkcd.com/comics/episode_vii.png"); 

     setProgress(0); 

     int numberOfURLs = urlStrings.size(); 

     for (int i = 0; i < numberOfURLs; i++) { 
     download(urlStrings.get(i), i, numberOfURLs); 
     } 

     return null; 
    } 

    /* 
    * Handle data from publish(), i.e., current file progress 
    */ 
    @Override 
    protected void process(java.util.List<Integer> progressList) { 
     final int progress = progressList.get(progressList.size() - 1); 
     currentProgressBar.setValue(progress); 
    } 

    /* 
    * Executed in event dispatching thread 
    */ 
    @Override 
    public void done() { 
     setCursor(null); //turn off the wait cursor 
     taskOutput.append("All files downloaded!\n"); 
    } 
    } // end of class Task 

    public ProgressBarDemo() { 
    super(new BorderLayout()); 

    //Create the demo's UI. 
    startButton = new JButton("Start"); 
    startButton.setActionCommand("start"); 
    startButton.addActionListener(this); 

    overallProgressBar = new JProgressBar(0, 100); 
    overallProgressBar.setValue(0); 
    overallProgressBar.setStringPainted(true); 

    currentProgressBar = new JProgressBar(0, 100); 
    currentProgressBar.setValue(0); 
    currentProgressBar.setStringPainted(true); 

    taskOutput = new JTextArea(5, 20); 
    taskOutput.setMargin(new Insets(5,5,5,5)); 
    taskOutput.setEditable(false); 

    JPanel panel = new JPanel(); 
    panel.setLayout(new GridLayout(3,2)); 
    panel.add(new JLabel("Current File")); 
    panel.add(currentProgressBar); 
    panel.add(new JLabel("Overall Progress")); 
    panel.add(overallProgressBar); 
    panel.add(startButton); 

    add(panel, BorderLayout.PAGE_START); 
    add(new JScrollPane(taskOutput), BorderLayout.CENTER); 
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); 
    } 

    /** 
    * Invoked when the user presses the start button. 
    */ 
    public void actionPerformed(ActionEvent evt) { 
    startButton.setEnabled(false); 
    setCursor(Cursor.getPredefinedCursor(Cursor.WAIT_CURSOR)); 
    //Instances of javax.swing.SwingWorker are not reusuable, so 
    //we create new instances as needed. 
    task = new Task(currentProgressBar); 
    task.addPropertyChangeListener(this); 
    task.execute(); 
    } 

    /** 
    * Invoked when task's progress property changes. 
    */ 
    public void propertyChange(PropertyChangeEvent evt) { 
    if ("progress" == evt.getPropertyName()) { 
     int progress = (Integer) evt.getNewValue(); 
     overallProgressBar.setValue(progress); 
    } 
    } 

    /** 
    * Create the GUI and show it. As with all GUI code, this must run 
    * on the event-dispatching thread. 
    */ 
    private static void createAndShowGUI() { 
    //Create and set up the window. 
    JFrame frame = new JFrame("ProgressBarDemo"); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

    //Create and set up the content pane. 
    JComponent newContentPane = new ProgressBarDemo(); 
    newContentPane.setOpaque(true); //content panes must be opaque 
    frame.setContentPane(newContentPane); 

    //Display the window. 
    frame.pack(); 
    frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
    //Schedule a job for the event-dispatching thread: 
    //creating and showing this application's GUI. 
    javax.swing.SwingUtilities.invokeLater(new Runnable() { 
     public void run() { 
     createAndShowGUI(); 
     } 
    }); 
    } 
}