我有一个ProgressMonitor pm和一个SwingWorker sw。我想按cancel上的pm - 按钮取消SwingWorker。我想这不应该太难，我读了一些关于SwingWorker和ProgressMonitor的教程，但我无法让它工作。
final ProgressMonitor pm = new ProgressMonitor(frame, "checking", "...", 0, 100);
final SwingWorker sw = new SwingWorker()
{
protected Object doInBackground() throws Exception
{
doSomethingAndUpdateProgress();
}
};
sw.addPropertyChangeListener(new PropertyChangeListener()
{
public void propertyChange(PropertyChangeEvent evt)
{
if(evt.getPropertyName().equals("progress"))
{
updateProgress();
}
if(pm.isCanceled())
{
cancelAction();
}
if(pm.isDone())
{
doneAction();
}
}
});
sw.execute();
进度更新工作正常，但pm.isCanceled()永远不会true。我想我需要一个用于ProgressMonitor的propertyChangeListener，但我不知道如何在那里添加一个。
答案 0 :(得分：4)
我读了一些关于SwingWorker和ProgressMonitor的教程，但我无法让它工作。
取消总是调用InteruptedExeption，
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
public class SwingWorkerExample extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
private final JButton startButton, stopButton;
private JScrollPane scrollPane = new JScrollPane();
private JList listBox = null;
private DefaultListModel listModel = new DefaultListModel();
private final JProgressBar progressBar;
private mySwingWorker swingWorker;
public SwingWorkerExample() {
super("SwingWorkerExample");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
getContentPane().setLayout(new GridLayout(2, 2));
startButton = makeButton("Start");
stopButton = makeButton("Stop");
stopButton.setEnabled(false);
progressBar = makeProgressBar(0, 99);
listBox = new JList(listModel);
scrollPane.setViewportView(listBox);
getContentPane().add(scrollPane);
//Display the window.
pack();
setVisible(true);
}
//Class SwingWorker<T,V> T - the result type returned by this SwingWorker's doInBackground
//and get methods V - the type used for carrying out intermediate results by this SwingWorker's
//publish and process methods
private class mySwingWorker extends javax.swing.SwingWorker<ArrayList<Integer>, Integer> {
//The first template argument, in this case, ArrayList<Integer>, is what s returned by doInBackground(),
//and by get(). The second template argument, in this case, Integer, is what is published with the
//publish method. It is also the data type which is stored by the java.util.List that is the parameter
//for the process method, which recieves the information published by the publish method.
@Override
protected ArrayList<Integer> doInBackground() {
//Returns items of the type given as the first template argument to the SwingWorker class.
if (javax.swing.SwingUtilities.isEventDispatchThread()) {
System.out.println("javax.swing.SwingUtilities.isEventDispatchThread() returned true.");
}
Integer tmpValue = new Integer(1);
ArrayList<Integer> list = new ArrayList<Integer>();
for (int i = 0; i < 100; i++) {
for (int j = 0; j < 100; j++) { //find every 100th prime, just to make it slower
tmpValue = FindNextPrime(tmpValue.intValue());
//isCancelled() returns true if the cancel() method is invoked on this class. That is the proper way
//to stop this thread. See the actionPerformed method.
if (isCancelled()) {
System.out.println("SwingWorker - isCancelled");
return list;
}
}
//Successive calls to publish are coalesced into a java.util.List, which is what is received by process,
//which in this case, isused to update the JProgressBar. Thus, the values passed to publish range from
//1 to 100.
publish(new Integer(i));
list.add(tmpValue);
}
return list;
}//Note, always use java.util.List here, or it will use the wrong list.
@Override
protected void process(java.util.List<Integer> progressList) {
//This method is processing a java.util.List of items given as successive arguments to the publish method.
//Note that these calls are coalesced into a java.util.List. This list holds items of the type given as the
//second template parameter type to SwingWorker. Note that the get method below has nothing to do with the
//SwingWorker get method; it is the List's get method. This would be a good place to update a progress bar.
if (!javax.swing.SwingUtilities.isEventDispatchThread()) {
System.out.println("javax.swing.SwingUtilities.isEventDispatchThread() + returned false.");
}
Integer percentComplete = progressList.get(progressList.size() - 1);
progressBar.setValue(percentComplete.intValue());
}
@Override
protected void done() {
System.out.println("doInBackground is complete");
if (!javax.swing.SwingUtilities.isEventDispatchThread()) {
System.out.println("javax.swing.SwingUtilities.isEventDispatchThread() + returned false.");
}
try {
//Here, the SwingWorker's get method returns an item of the same type as specified as the first type parameter
//given to the SwingWorker class.
ArrayList<Integer> results = get();
for (Integer i : results) {
listModel.addElement(i.toString());
}
} catch (Exception e) {
System.out.println("Caught an exception: " + e);
}
startButton();
}
boolean IsPrime(int num) { //Checks whether a number is prime
int i;
for (i = 2; i <= num / 2; i++) {
if (num % i == 0) {
return false;
}
}
return true;
}
protected Integer FindNextPrime(int num) { //Returns next prime number from passed arg.
do {
if (num % 2 == 0) {
num++;
} else {
num += 2;
}
} while (!IsPrime(num));
return new Integer(num);
}
}
private class TaskListener implements PropertyChangeListener {
private String name;
TaskListener(String name) {
this.name = name;
}
@Override
public void propertyChange(PropertyChangeEvent e) {
System.out.println(name + ": "
+ e.getOldValue() + " -> " + e.getNewValue());
}
}
private JButton makeButton(String caption) {
JButton b = new JButton(caption);
b.setActionCommand(caption);
b.addActionListener(this);
getContentPane().add(b);
return b;
}
private JProgressBar makeProgressBar(int min, int max) {
JProgressBar progressBar1 = new JProgressBar();
progressBar1.setMinimum(min);
progressBar1.setMaximum(max);
progressBar1.setStringPainted(true);
progressBar1.setBorderPainted(true);
getContentPane().add(progressBar1);
return progressBar1;
}
private void startButton() {
startButton.setEnabled(true);
stopButton.setEnabled(false);
System.out.println("SwingWorker - Done");
}
@Override
public void actionPerformed(ActionEvent e) {
if ("Start" == null ? e.getActionCommand() == null : "Start".equals(e.getActionCommand())) {
startButton.setEnabled(false);
stopButton.setEnabled(true);
// Note that it creates a new instance of the SwingWorker-derived class. Never reuse an old one.
(swingWorker = new mySwingWorker()).execute(); // new instance
swingWorker.addPropertyChangeListener(new TaskListener("Task"));
} else if ("Stop" == null ? e.getActionCommand() == null : "Stop".equals(e.getActionCommand())) {
startButton.setEnabled(true);
stopButton.setEnabled(false);
swingWorker.cancel(true); // causes isCancelled to return true in doInBackground
swingWorker = null;
}
}
public static void main(String[] args) {
// Notice that it kicks it off on the event-dispatching thread, not the main thread.
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
SwingWorkerExample swingWorkerExample = new SwingWorkerExample();
}
});
}
}
答案 1 :(得分：4)
在执行长时间运行的任务期间，您需要定期检查ProgressMonitor是否已取消。你的工作是在取消任务的地方进行检查 - 否则谁知道你可以留下什么资源。
基本上，您希望更改doSomethingAndUpdateProgress()方法，以便检查ProgressMonitor是否已取消。
这是一个演示如何工作的演示：
import java.awt.*;
import javax.swing.*;
public class TempProject extends Box{
public TempProject(){
super(BoxLayout.Y_AXIS);
final ProgressMonitor pm = new ProgressMonitor(this, "checking", "...", 0, 100);
final SwingWorker sw = new SwingWorker<Integer, Integer>()
{
protected Integer doInBackground() throws Exception
{
int i = 0;
//While still doing work and progress monitor wasn't canceled
while (i++ < 100 && !pm.isCanceled()) {
System.out.println(i);
publish(i);
Thread.sleep(100);
}
return null;
}
@Override
protected void process(java.util.List<Integer> chunks) {
for (int number : chunks) {
pm.setProgress(number);
}
}
};
sw.execute();
}
public static void main(String args[])
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.setContentPane(new TempProject());
frame.pack();
frame.setVisible(true);
}
});
}
}