在Netbeans中,我创建了一个GUI项目,它使用框架前端,我可以添加组件并双击编辑他们的事件。我指的是具有“源”,“设计”和“历史”标签的窗口。
以下是组件和关系:
1-打开文件选择器的按钮。
2- TextArea显示文件选择器的结果。如果用户选择文件,它将在TextArea中显示文件名;否则会写“由用户取消”。
3-同时,如果用户选择了一个文件,我想打开一个“请稍候”对话框SwingWorker
并在后台进行一些工作。
问题是,当用户选择文件时,我没有看到请等待对话框! Netbeans生成的完整代码可在pastebin获得。部分代码如下所示:
private void OpenSongFileActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
JFileChooser fileChooser = new JFileChooser();
fileChooser.setAcceptAllFileFilterUsed(false);
FileNameExtensionFilter filter = new FileNameExtensionFilter("MP3 files", "mp3");
fileChooser.addChoosableFileFilter(filter);
fileChooser.setCurrentDirectory(new File(System.getProperty("user.dir")));
int result = fileChooser.showOpenDialog(this);
if (result != JFileChooser.APPROVE_OPTION) {
//ReadInfo.setText("No song has been selected");
System.out.println("OpenSongFile canceled by user");
return;
}
final JDialog loading = new JDialog(this);
JPanel p1 = new JPanel(new BorderLayout());
p1.add(new JLabel("Please wait..."), BorderLayout.CENTER);
loading.setUndecorated(true);
loading.getContentPane().add(p1);
loading.pack();
loading.setLocationRelativeTo(this);
loading.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
loading.setModal(true);
SwingWorker<String, Void> worker = new SwingWorker<String, Void>() {
@Override
protected String doInBackground() throws InterruptedException {
for (int i = 0; i < 10000; i++)
for (int j = 0; j < 10000; j++)
;
return "hello";
}
@Override
protected void done() {
loading.dispose();
}
};
worker.execute();
loading.setVisible(true);
try {
worker.get();
} catch (Exception e1) {
e1.printStackTrace();
}
File selectedFile = fileChooser.getSelectedFile();
ReadInfo.setText("Selected file: " + selectedFile.getAbsolutePath());
}
P.S:我使用了解释here的SwingWorker代码。
答案 0 :(得分:1)
worker.get();
会一直阻止,直到SwingWorker
返回,这意味着你阻止了EDT,阻止了对话框的显示。
相反,请使用SwingWorker
PropertyChangeListener
支持并监控START
和DONE
事件
SwingWorker<String, Void> worker = new SwingWorker<String, Void>() {
@Override
protected String doInBackground() throws InterruptedException {
Thread.sleep(5000);
return "hello";
}
@Override
protected void done() {
loading.dispose();
}
};
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
System.out.println(evt.getPropertyName());
Object value = evt.getNewValue();
if (value instanceof SwingWorker.StateValue) {
SwingWorker.StateValue state = (SwingWorker.StateValue) value;
switch (state) {
case DONE: {
try {
String result = worker.get();
JOptionPane.showMessageDialog(null, result);
} catch (InterruptedException | ExecutionException ex) {
ex.printStackTrace();
}
}
break;
}
}
}
});
worker.execute();
loading.setVisible(true);
另一个问题是你的循环可能运行得如此之快,以至于窗口在屏幕上实现之前已经关闭。
例如,我只是使用Thread.sleep
暂停doInBackground
方法5秒......
import java.awt.BorderLayout;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class Memory extends JFrame {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
makeItSo();
}
});
}
public static void makeItSo() {
final JDialog loading = new JDialog();
JPanel p1 = new JPanel(new BorderLayout());
p1.add(new JLabel("Please wait..."), BorderLayout.CENTER);
loading.setUndecorated(true);
loading.getContentPane().add(p1);
loading.pack();
loading.setLocationRelativeTo(null);
loading.setDefaultCloseOperation(JDialog.DO_NOTHING_ON_CLOSE);
loading.setModal(true);
SwingWorker<String, Void> worker = new SwingWorker<String, Void>() {
@Override
protected String doInBackground() throws InterruptedException {
Thread.sleep(5000);
return "hello";
}
@Override
protected void done() {
loading.dispose();
}
};
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
System.out.println(evt.getPropertyName());
Object value = evt.getNewValue();
if (value instanceof SwingWorker.StateValue) {
SwingWorker.StateValue state = (SwingWorker.StateValue) value;
switch (state) {
case DONE: {
try {
String result = worker.get();
JOptionPane.showMessageDialog(null, result);
} catch (InterruptedException | ExecutionException ex) {
ex.printStackTrace();
}
}
break;
}
}
}
});
worker.execute();
loading.setVisible(true);
}
}