SwingWorkerの一時停止と再開
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Posted by aterai at
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概要
SwingWorker
で処理の一時停止と再開を行います。
Screenshot
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サンプルコード
class RunAction extends AbstractAction {
public RunAction() {
super("run");
}
@Override public void actionPerformed(ActionEvent evt) {
JProgressBar bar1 = new JProgressBar(0, 100);
JProgressBar bar2 = new JProgressBar(0, 100);
runButton.setEnabled(false);
canButton.setEnabled(true);
pauseButton.setEnabled(true);
statusPanel.removeAll();
statusPanel.add(bar1, BorderLayout.NORTH);
statusPanel.add(bar2, BorderLayout.SOUTH);
statusPanel.revalidate();
worker = new SwingWorker<String, Progress>() {
private final Random r = new Random();
@Override public String doInBackground() {
int current = 0;
int lengthOfTask = 12; //filelist.size();
publish(new Progress(Component.LOG, "Length Of Task: " + lengthOfTask));
publish(new Progress(Component.LOG, "\n---------------------------\n"));
while (current < lengthOfTask && !isCancelled()) {
publish(new Progress(Component.LOG, "*"));
if (!bar1.isDisplayable()) {
return "Disposed";
}
try {
convertFileToSomething();
} catch (InterruptedException ie) {
return "Interrupted";
}
publish(new Progress(Component.TOTAL, 100 * current / lengthOfTask));
current++;
}
publish(new Progress(Component.LOG, "\n"));
return "Done";
}
private void convertFileToSomething() throws InterruptedException {
boolean flag = false;
int current = 0;
int lengthOfTask = 10 + r.nextInt(50);
while (current <= lengthOfTask && !isCancelled()) {
if (isPaused) {
try {
Thread.sleep(500);
} catch (InterruptedException ie) {
return;
}
publish(new Progress(Component.PAUSE, flag));
flag ^= true;
continue;
}
int iv = 100 * current / lengthOfTask;
Thread.sleep(20);
publish(new Progress(Component.FILE, iv + 1));
current++;
}
}
@Override protected void process(java.util.List<Progress> chunks) {
for (Progress s: chunks) {
switch (s.component) {
case TOTAL: bar1.setValue((Integer) s.value); break;
case FILE: bar2.setValue((Integer) s.value); break;
case LOG: area.append((String) s.value); break;
case PAUSE: {
if ((Boolean) s.value) {
area.append("*");
} else {
try {
Document doc = area.getDocument();
doc.remove(doc.getLength() - 1, 1);
} catch (Exception ex) {
ex.printStackTrace();
}
}
break;
}
}
}
}
@Override public void done() {
// ...
}
};
worker.execute();
}
}
// ...
private boolean isPaused = false;
class PauseAction extends AbstractAction {
public PauseAction() {
super("pause");
}
@Override public void actionPerformed(ActionEvent evt) {
isPaused = (worker != null && !worker.isCancelled() && !isPaused);
JButton b = (JButton) evt.getSource();
b.setText(isPaused ? "resume" : "pause");
}
}
View in GitHub: Java, Kotlin解説
上記のサンプルでは、SwingWorker#doInBackground()
内のループで一時停止のフラグを参照し、一時停止状態の場合は本来の処理(上記のサンプルではカウントアップするだけ)を行わずにThread.sleep(...)
と停止中を表現するコンポーネントの更新(JTextArea
の文字列を点滅)のみ繰り返すSwingWorker
を使用しています。