爪哇人的勇气。invokeLater、SwingWorker和gif图标动画问题
我试图加载一个gif图标,而我在后台做一些昂贵的工作。但问题是,gif(动画)图标未加载
如果我用png替换gif图标,效果很好
下面是测试类代码
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
// TODO Auto-generated method stub
JFrame frame = new JFrame();
frame.setBounds(100, 100, 200, 100);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
frame.getContentPane().add(panel);
JButton loginButton = new JButton("Login");
panel.add(loginButton);
frame.add(panel);
frame.setVisible(true);
loginButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
URL urlProcessing = Test.class.getResource("processing.gif");
//URL urlProcessing = Test.class.getResource("processing.png");
ImageIcon processingIcon = new ImageIcon(urlProcessing);
loginButton.setText("Authenticating...");
loginButton.setIcon(processingIcon);
loginButton.revalidate();
loginButton.repaint();
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
Worker worker = new Worker(frame);
try {
worker.doInBackground();
} catch (Exception e1) {
e1.printStackTrace();
}
}
});
}
});
}
}
当用户点击登录按钮时,我更改了按钮的文本,并在其上放置了gif图标。在
SwingUtilities.invokeLater(new Runnable() {
方法通过SwingWorker线程启动后台昂贵任务。现在,不需要发布和处理SwingWorker类的方法,因为我在后台任务期间不做任何工作
如果我删除“SwingUtilities.invokeLater(new Runnable(){”方法并直接调用SwingWorker类,那么gif和png图标都不起作用(显示在按钮上)
我尝试用简单的线程来改变文本,并在按钮上设置图标,但效果并不理想
下面是SwingWorker类代码
import javax.swing.JFrame;
import javax.swing.SwingWorker;
public class Worker extends SwingWorker<String, String> implements Runnable {
private JFrame testFrame;
// some public and private properties
public Worker(JFrame frame){
// doing some assignments
this.testFrame = frame;
}
@Override
protected void done() {
// TODO Auto-generated method stub
super.done();
System.out.println("Done method called");
}
@Override
protected String doInBackground() throws Exception {
int i = 0;
String chunks = null;
publish(chunks);
// Doing some very expensive work, HTTP request, DB operations etc...
while (i < 10) {
Thread.sleep(1000);
System.out.println("Value of i: "+i);
i++;
}
this.done();
testFrame.setVisible(false);
return null;
}
}
知道吗?GUI主线程中发生了什么?错在哪里
# 1 楼答案
你不应该直接调用
doInBackground
,你应该调用execute
。您还应该能够在UI线程中进行该调用(即,不需要在invokeLater
中调用它)。在doInBackground
实现中,应该在UI线程中对UI进行更改(即invokeLater
应该在那里使用)