使用SwingWorker在GUI中添加进度条

Question

我使用SwingWorker用Java Swing API制作进度条。

我有一个扩展SwingWorker 的类

    class Swinger extends SwingWorker {
private ClassAnalyzer classAnalyzer;
public Swinger(ClassAnalyzer classAnalyzer){
     this.classAnalyzer = classAnalyzer;
}
        @Override
        public Void doInBackground() throws InterruptedException {
            try
        {     
            int progress = 0;
            while (progress < 100) {
 // at this point I make certain elaboration on classAnalyzer                 
                progress++;
                //Call the process method to update the GUI
                publish(progress);
            }                       
        }
        catch(InterruptedException e)
        {
        }
        return null;
    }
    @Override
    protected void process(List chunks) {
     for (Integer chunk : chunks) {
        progressBar.setValue(chunk);
        //if the switchtype checkbox is selected then
        //change the progressbar to a determined type
        //once the progress has reached 50
        if (chunk > 49)
        {
            if (switchType.isEnabled() && switchType.isSelected())
            {
                progressBar.setStringPainted(true);
            }
        }
     }
 }
}

和第二节课（我正在写一篇）

 public Tester()
{
    JFrame guiFrame = new JFrame();
    //make sure the program exits when the frame closes
    guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    guiFrame.setTitle("Creating a Table Example");
    guiFrame.setSize(700,200);
    //This will center the JFrame in the middle of the screen
    guiFrame.setLocationRelativeTo(null);

    goButton = new JButton("Go");
    goButton.setActionCommand("Go");
    goButton.addActionListener(new ActionListener()
    {
        //When the button is clicked the SwingWorker class is executed and
        //the button is disabled
        @Override
        public void actionPerformed(ActionEvent event)
        {
            progressBar.setStringPainted(progressType.isSelected());
            ClassAnalyzer c = new ClassAnalyzer();
            Swinger task = new Swinger(c);
            task.execute();
            int methods = c.getNumberOfMethods();
            if(methods == 0){
            JOptionPane.showMessageDialogo(null, "methods not found");
            }
            goButton.setEnabled(false);
        }
    });
    }

当我在测试仪中启动第二个类时，在进度条出现之前会显示消息"methods not found"，而如果之后该怎么办？

Answer 1

task.execute()将启动一个后台（从中调用doInBackground方法），程序将继续执行。

task.execute()不是一个阻塞方法，这就是使用它的原因，所以你不会阻塞事件调度线程

您可以使用PropertyChangeListener 监控SwingWorker的状态

final ClassAnalyzer c = new ClassAnalyzer();
Swinger task = new Swinger(c);
task.addPropertyChangeListener(new PropertyChangeListener() {
    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        if (evt.getPropertyName().equals("state") && evt.getNewValue().equals(SwingWorker.StateValue.DONE)) {
            int methods = c.getNumberOfMethods();
            if(methods == 0){
                JOptionPane.showMessageDialogo(null, "methods not found");
            }
        }
    }
});
task.execute();

Answer 2

SwingWorker类还定义了一个done方法，您可以在该方法中定义任务完成后要执行的操作。

class Swinger extends SwingWorker {
    // all the rest of your code ^^
    @Override
    protected void done() {
        if(this.classAnalyzer.getNumberOfMethods() == 0)
            JOptionPane.showMessageDialog(null, "methods not found");            
    }
}

您不必担心线程问题，因为EDT上也调用了此方法。