用的SwingWorker

Question

問題，我試圖讓一個SwingWorker的工作。 我有下面的代碼的那一刻：

public class ImageWorker extends SwingWorker<Void, Void> implements KeyListener 
{ 
private JLabel imageLabel; 
private ImageIcon basicImage; 
private ImageIcon whiteImage; 
public static void main(String[] args) 
{ 
    new ImageWorker();  
} 

public ImageWorker() 
{ 
    final JFrame frame = new JFrame(); 
    imageLabel = new JLabel(); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    frame.setSize(400, 400); 
    frame.getContentPane().add(imageLabel); 
    frame.setVisible(true); 
    try 
    { 
     basicImage = new ImageIcon(ImageIO.read(new File("src\\img\\basis1.jpg")).getScaledInstance(1024, 768, Image.SCALE_SMOOTH)); 
     whiteImage = new ImageIcon(ImageIO.read(new File("src\\img\\wit.jpg")).getScaledInstance(1024, 768, Image.SCALE_SMOOTH));  
    } 
    catch(IOException ex) 
    { 
     ex.getMessage(); 
    } 
    this.execute(); 

} 

@Override 
protected Void doInBackground() 
{ 
    try 
    { 
     while (true) 
     { 
      displayImage(basicImage); 
      Thread.sleep(1000L); 
      if(isCancelled()) 
       return null; 
     } 
    } 
    catch(InterruptedException e) 
    { 
     e.getMessage(); 
    } 
    return null; 
} 

private void displayImage(final Icon image) 
{ 
    SwingUtilities.invokeLater(new Runnable() 
    { 
     public void run() 
     { 
      imageLabel.setIcon(image); 
     } 
    });  
} 

我期待的圖像出現在的JLabel，但我只看到JFrame中彈出。文件正確加載我已經在另一個設置中測試過。 任何指針？

Answer 1

下面是一個使用Timer而不是使用SwingWorker的例子，它確實不適合您的情況。請注意，它與現有代碼沒有太大差別。

import java.awt.Image; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.KeyEvent; 
import java.awt.event.KeyListener; 
import java.io.File; 
import java.io.IOException; 

import javax.imageio.ImageIO; 
import javax.swing.ImageIcon; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.Timer; 

public class ImageWorker implements KeyListener 
{ 
    private JLabel imageLabel; 
    private ImageIcon basicImage; 
    private ImageIcon whiteImage; 
    private boolean isBasic = true; 
    private int delay = 1000; //milliseconds 
    private Timer timer; 

    public static void main(String[] args) 
    { 
     new ImageWorker(); 
    } 

    public ImageWorker() 
    { 
     final JFrame frame = new JFrame(); 
     imageLabel = new JLabel(); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.setSize(400, 400); 
     frame.getContentPane().add(imageLabel); 
     frame.setVisible(true); 

     try 
     { 
      basicImage = new ImageIcon(ImageIO.read(new File("src\\img\\basis1.jpg")).getScaledInstance(1024, 768, Image.SCALE_SMOOTH)); 
      whiteImage = new ImageIcon(ImageIO.read(new File("src\\img\\wit.jpg")).getScaledInstance(1024, 768, Image.SCALE_SMOOTH));  
     } 
     catch (IOException ex) 
     { 
      ex.getMessage(); 
      ex.printStackTrace(); 
     } 

     frame.addKeyListener(this); 
     ActionListener taskPerformer = new ActionListener() { 
      public void actionPerformed(ActionEvent evt) { 
       if(isBasic) { 
        //display basic image 
        imageLabel.setIcon(basicImage); 
       } 
       else { 
        //display white image 
        imageLabel.setIcon(whiteImage); 
       } 

       //toggle the flag 
       isBasic = !isBasic; 
      } 
     }; 
     //use a timer instead of SwingWorker 
     timer = new Timer(delay, taskPerformer); 
     timer.start(); 

    } 



    @Override 
    public void keyPressed(KeyEvent e) 
    { 
     //key pressed, we want to stop toggling so stop the timer 
     timer.stop(); 
     //do whatever else you were doing to set the value for isCancelled(); 
    } 

    @Override 
    public void keyReleased(KeyEvent e) 
    { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void keyTyped(KeyEvent e) 
    { 
     // TODO Auto-generated method stub 

    } 
} 

Answer 2

A SwingWorker不適合您的情況在swing包中查看Timer。這裏是一個鏈接到API：http://download.oracle.com/javase/6/docs/api/javax/swing/Timer.html

你有定時器的運行，改變每一秒，因爲圖像被你所需要的。

而且，只要你有例外，至少打印出堆棧跟蹤或消息。否則，您將不知道是否發生異常並被捕獲。