JOptionPane 是一个 Swing 方法，应该在 EDT、Event D ispatch T线程上调用，并且只能在这个线程上调用，因此它建议您上面的所有代码都应该在 EDT 上，并且您的大部分调用都是完全不必要。唯一必要的将是主要的，您启动 Swing GUI 代码的地方，以及需要从后台线程中进行 Swing 调用的任何区域。同样，如果上述任何代码是在后台线程中编写的，那么 JOptionPane 不应该在该线程中。SwingUtilities.invokeLater(new Runnable()
有关此答案或任何其他答案的更具体信息，请在您的问题中提供更具体的信息。让我们结束所有的困惑。让我们全面快速地了解您的问题的最佳方法是，如果您要创建并发布一个最小的示例程序，这是一个小而完整的程序，只有必要的代码来演示您的问题，我们可以复制、粘贴、无需修改即可编译运行。
我有一个隐秘的怀疑，沿着 MVC 线进行体面的重构可以解决你的大部分问题。您的代码非常线性，它的代码行必须彼此跟随，以及它的 if 块，并且它还与您的 GUI 紧密耦合，这对我来说是两个危险信号。也许更好的是更少的线性代码，更多的事件和状态驱动代码，后台代码通过观察者通知与 GUI 交互的代码，以及后台代码同样响应来自控制通知的 GUI 状态变化的代码。
您的控件需要两个 SwingWorker，一个用于获取行数，另一个用于获取其余数据（如果用户决定这样做）。我会向第一个 SwingWorker 添加一个 PropertyChangeListener，以便在行计数数据准备好时收到通知，然后一旦准备好，将其呈现给视图以供用户选择是否继续。如果他决定继续，我会调用第二个 SwingWorker 来获取数据的主体。
例如，我正在谈论的内容的粗略草图：
import java.awt.Dialog.ModalityType;
import java.awt.Dimension;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
@SuppressWarnings("serial")
public class SwingWorkerFooView extends JPanel {
private static final int PREF_W = 400;
private static final int PREF_H = 300;
private JProgressBar progressBar;
private JDialog dialog;
public SwingWorkerFooView() {
add(new JButton(new ButtonAction("Foo", this)));
}
@Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
public boolean showOptionGetAllData(int numberOfRows) {
String message = "Number of rows = " + numberOfRows + ". Get all of the data?";
String title = "Get All Of Data?";
int optionType = JOptionPane.YES_NO_OPTION;
int result = JOptionPane.showConfirmDialog(this, message, title, optionType);
return result == JOptionPane.YES_OPTION;
}
public void showProgressBarDialog() {
progressBar = new JProgressBar();
progressBar.setIndeterminate(true);
Window window = SwingUtilities.getWindowAncestor(this);
dialog = new JDialog(window, "Hang on", ModalityType.APPLICATION_MODAL);
JPanel panel = new JPanel();
panel.add(progressBar);
dialog.add(panel);
dialog.pack();
dialog.setLocationRelativeTo(this);
dialog.setVisible(true);
}
public void closeProgressBarDialog() {
dialog.dispose();
}
private static void createAndShowGui() {
JFrame frame = new JFrame("SwingWorkerFoo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new SwingWorkerFooView());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
@SuppressWarnings("serial")
class ButtonAction extends AbstractAction {
Workers workers = new Workers();
private SwingWorker<Integer, Void> firstWorker;
private SwingWorker<List<String>, Void> secondWorker;
private SwingWorkerFooView mainGui;
public ButtonAction(String name, SwingWorkerFooView mainGui) {
super(name);
this.mainGui = mainGui;
}
@Override
public void actionPerformed(ActionEvent e) {
firstWorker = workers.createFirstWorker();
firstWorker.addPropertyChangeListener(new FirstPropertyChangeListener());
firstWorker.execute();
mainGui.showProgressBarDialog();
}
private class FirstPropertyChangeListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
mainGui.closeProgressBarDialog();
try {
int numberOfRows = firstWorker.get();
boolean getAllData = mainGui.showOptionGetAllData(numberOfRows);
if (getAllData) {
secondWorker = workers.createSecondWorker();
secondWorker.addPropertyChangeListener(new SecondPropertyChangeListener());
secondWorker.execute();
mainGui.showProgressBarDialog();
} else {
// user decided not to get all data
workers.cleanUp();
}
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
private class SecondPropertyChangeListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getNewValue() == SwingWorker.StateValue.DONE) {
mainGui.closeProgressBarDialog();
try {
List<String> finalData = secondWorker.get();
// display finalData in the GUI
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
}
class Workers {
// database object that may be shared by two SwingWorkers
private Object someDataBaseVariable;
private Random random = new Random(); // just for simulation purposes
private class FirstWorker extends SwingWorker<Integer, Void> {
@Override
protected Integer doInBackground() throws Exception {
// The Thread.sleep(...) is not going to be in final production code
// it's just to simulate a long running task
Thread.sleep(4000);
// here we create our database object and check how many rows there are
int rows = random.nextInt(10 + 10); // this is just for demonstration purposes only
// here we create any objects that must be shared by both SwingWorkers
// and they will be saved in a field of Workers
someDataBaseVariable = "Fubar";
return rows;
}
}
private class SecondWorker extends SwingWorker<List<String>, Void> {
@Override
protected List<String> doInBackground() throws Exception {
// The Thread.sleep(...) is not going to be in final production code
// it's just to simulate a long running task
Thread.sleep(4000);
List<String> myList = new ArrayList<>();
// here we go through the database filling the myList collection
return myList;
}
}
public SwingWorker<Integer, Void> createFirstWorker() {
return new FirstWorker();
}
public void cleanUp() {
// TODO clean up any resources and database stuff that will not be used.
}
public SwingWorker<List<String>, Void> createSecondWorker() {
return new SecondWorker();
}
}
所有这一切的关键是不要以线性控制台程序的方式思考，而是使用观察者设计模式，即某种侦听器来检查 GUI 和模型的状态变化。
它本质上是：