基于Oracle Concurrency guidelines我试图对我的GUI进行更新。我的问题是,GUI更新在EDT内的新线程中被调用,这导致了我很多不同的失败。如何让EDT等待后台线程?
下面这段代码就可以运行和我的样本GUI更新,一个简单的倒计时:
import java.awt.Component;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.util.Timer;
import java.util.TimerTask;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class Chronometer2 {
int COUNT = 5000;
CountTask countTask;
private static final Insets INSETS = new Insets(1, 1, 1, 1);
public Chronometer2(){
(countTask= new CountTask()).execute();
}
private static void addComponent(Container container, Component component, int gridx, int gridy,
int gridwidth, int gridheight, int anchor, int fill) {
GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth, gridheight, 1.0, 1.0,
anchor, fill, INSETS, 0, 0);
container.add(component, gbc);
}
public int returnCount(){
System.out.println("My count: " + COUNT);
return COUNT;
}
public void decreaseTime() {
COUNT--;
}
public int getTime() {
return COUNT;
}
private class CountTask extends SwingWorker<Void, Chronometer2>{
@Override
protected Void doInBackground() throws Exception {
// TODO Auto-generated method stub
final JFrame messageFrame = new JFrame();
final JLabel message = new JLabel("Next query in " + COUNT/1000 + " seconds.");
messageFrame.setLayout(new GridBagLayout());
messageFrame.setTitle("Warning");
messageFrame.setSize(500,100);
messageFrame.setLocationRelativeTo(null);
addComponent(messageFrame, message, 0, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.CENTER);
messageFrame.setVisible(true);
final Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
decreaseTime();
message.setText("Preventing connection block. Next query in " + COUNT/1000 + " seconds.");
if(getTime()==0){
messageFrame.dispose();
timer.cancel();
}
}
}, 1, 1);
return null;
}
}
public static void main(String[] args){
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Chronometer2();
}
});
}
}
由于样品是从主线程,它的正常工作调用。但是从我的应用程序调用正在EDT内部进行,因为我需要在显示消息之前按下按钮并触发一个操作。我创建了一个新线程来调用Swing公用程序(它不能直接在EDT内部调用),即使我遇到问题,因为直到现在我仍无法让EDT等待后台线程完成,然后继续前进下一个查询。这是代码的EDT内伸展:
Thread test = new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
try {
SwingUtilities.invokeAndWait(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
new CountScreen();
}
});
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
test.start();
我也tryed与wait()
,notifiy()
和定时器任务,但问题是相同的处理这一点;下面是其他代码可以运行:
import java.awt.Component;
import java.awt.Container;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.util.Timer;
import java.util.TimerTask;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Chronometer {
private static final Insets INSETS = new Insets(1, 1, 1, 1);
private int TIMER = 3000;
public Chronometer(){
double timeToNext = System.currentTimeMillis() + 30000;
double timeDifference = 30000;
final JFrame messageFrame = new JFrame();
messageFrame.setLayout(new GridBagLayout());
messageFrame.setTitle("Warning");
final JLabel message = new JLabel("Next query in " + timeDifference/1000 + " seconds.");
messageFrame.setSize(500,100);
messageFrame.setLocationRelativeTo(null);
addComponent(messageFrame, message, 0, 0, 1, 1, GridBagConstraints.CENTER, GridBagConstraints.CENTER);
messageFrame.setVisible(true);
System.out.println(Thread.currentThread().getName());
final Timer timer = new Timer();
timer.schedule(new TimerTask() {
@Override
public void run() {
synchronized (timer) {
decreaseTime();
message.setText("Preventing connection block. Next query in " + TIMER/1000 + " seconds.");
if(getTime()==0){
System.out.println("Im here");
timer.notify();
System.out.println("Im here 2");
messageFrame.dispose();
System.out.println("Im here 3");
timer.cancel();
}
}
}
}, 1, 1);
synchronized (timer) {
try {
timer.wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
System.out.println("Done");
}
private static void addComponent(Container container, Component component, int gridx, int gridy,
int gridwidth, int gridheight, int anchor, int fill) {
GridBagConstraints gbc = new GridBagConstraints(gridx, gridy, gridwidth, gridheight, 1.0, 1.0,
anchor, fill, INSETS, 0, 0);
container.add(component, gbc);
}
public void decreaseTime() {
TIMER--;
}
public int getTime() {
return TIMER;
}
public static void main(String[] args){
Chronometer c = new Chronometer();
}
}
所以,我几乎3天纳闷,我怎么能解决这个问题?任何建议都非常受欢迎;提前致谢。
阅读'SwingWorker' API。 http://docs.oracle.com/javase/tutorial/uiswing/concurrency/worker.html –
认为我的SwingWorker子类应该在EDT内调用,而不是为它创建一个Thread并在其内运行,这是否正确? Swing公用事业? –
SwingWorker的意义在于你不必管理自己的线程。不管你从哪个线程调用'execute','doInBackground'都将在后台线程上调用(由SwingWorker内部管理),'process'和'done'将在EDT上运行。 –