好的，这是我昨天提出的问题的后续问题，“Error handling in SwingWorker。”
考虑到可能可以在SwingUtilities#invokeAndWait()内拨打SwingWorker#doInBackground()这一事实，我想进一步向前推进并询问：可能也可以在后台线程中调用SwingUtilities#invokeLater()吗？
另一个SSCCE来说明：
public class NewClass extends javax.swing.JFrame {
public NewClass() {
jScrollPane1 = new javax.swing.JScrollPane();
atable = new javax.swing.JTable();
jButton1 = new javax.swing.JButton();
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
atable.setModel(new javax.swing.table.DefaultTableModel(
new Object[][]{
{null, null},
{null, null},
{null, null},
{null, null}
},
new String[]{
"Title 1", "Title 2"
}
));
jScrollPane1.setViewportView(atable);
jButton1.setText("Go");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 380, Short.MAX_VALUE)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addGap(0, 0, Short.MAX_VALUE)
.addComponent(jButton1)))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 228, Short.MAX_VALUE)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jButton1)
.addContainerGap())
);
pack();
setLocationByPlatform(true);
setVisible(true);
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
new Task();
}
class Task extends javax.swing.SwingWorker<Void, Object[]> {
DeterminateLoadingFrame dlf;
public Task() {
dlf = new DeterminateLoadingFrame();
atable.setModel(new javax.swing.table.DefaultTableModel(
new Object[][]{},
new String[]{
"Title 1", "Title 2"
}
));
dlf.setMaximum(1000);
execute();
}
@Override
protected void process(java.util.List<Object[]> chunks) {
for (Object[] row : chunks) {
((javax.swing.table.DefaultTableModel) atable.getModel()).addRow(row);
}
}
@Override
protected Void doInBackground() throws Exception {
for (int i = 0; i < 1000; i++) {
final int j = i;
Object[] row = new Object[2];
row[0] = "row " + i;
row[1] = Math.round(Math.random() * 100);
publish(row);
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
dlf.changeText("Processing " + j + " of " + 1000);
dlf.setValue(j);
}
});
Thread.sleep(100);
}
return null;
}
@Override
protected void done() {
if (!isCancelled()) {
try {
get();
} catch (java.util.concurrent.ExecutionException | InterruptedException e) {
e.printStackTrace();
}
}
dlf.dispose();
}
}
class DeterminateLoadingFrame extends javax.swing.JFrame {
javax.swing.JLabel jLabel1;
javax.swing.JProgressBar jProgressBar1;
public DeterminateLoadingFrame() {
jProgressBar1 = new javax.swing.JProgressBar();
jLabel1 = new javax.swing.JLabel();
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
setTitle("Loading");
jLabel1.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
jLabel1.setText("Loading ...");
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
.addContainerGap()
.addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
.addComponent(jLabel1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 182, Short.MAX_VALUE)
.addComponent(jProgressBar1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 182, Short.MAX_VALUE))
.addContainerGap())
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
.addComponent(jProgressBar1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
);
pack();
setAlwaysOnTop(true);
setLocationRelativeTo(null);
setVisible(true);
setAlwaysOnTop(false);
}
public void changeText(String message) {
this.jLabel1.setText(message);
System.out.println(message);
}
public void setMaximum(int max) {
jProgressBar1.setMaximum(max);
}
public void setValue(int n) {
jProgressBar1.setValue(n);
}
}
public static void main(String args[]) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
new NewClass();
}
});
}
private javax.swing.JTable atable;
private javax.swing.JButton jButton1;
private javax.swing.JScrollPane jScrollPane1;
}
在此SSCCE中，我们正在更新DeterminateLoadingFrame以更新用户有关正在发生的事情，同时通过publish()和process()发布结果。
这似乎与昨天提出的原始问题一样不正统。然而，我无法提出任何理由这不是一个好主意。我们坚持正确的线程政策。以这种方式更新GUI似乎（对我来说）非常有用和多才多艺。事实上，还有process()和publish()。
此外：完成SSCCE所说明的内容将更难严格地使用process()和publish()，因为您如何将i的值传递给process()方法？< / p>
答案 0 :(得分：3)
另一个解决方案是使用SwingWorker的先天SwingPropertyChangeSupport并通知所有侦听器相关绑定属性的更改。您可以使用SwingWorkers已经拥有的进度绑定属性，但是如果您的属性从0到100，则只能使用此属性。如果您有一个不同的值（此处为1000），则必须使用自己的属性。由于PropertyChangeSupport对象是SwingPropertyChangeSupport，因此所有通知都将在Swing事件线程上完成。我喜欢这提供的解耦 - SwingWorker不需要知道谁在听什么，或者对信息做了什么。
例如，
class Task extends javax.swing.SwingWorker<Void, Object[]> {
public static final String ROW_COUNT = "row count";
DeterminateLoadingFrame dlf;
private int rowCount = 0;
public Task() {
dlf = new DeterminateLoadingFrame(); // and I would pass this in from the GUI
atable.setModel(new javax.swing.table.DefaultTableModel(
new Object[][] {}, new String[] { "Title 1", "Title 2" }));
dlf.setMaximum(1000);
// execute(); // I reserve this for the calling code.
}
public int getRowCount() {
return rowCount;
}
public void setRowCount(int newValue) {
int oldValue = this.rowCount;
this.rowCount = newValue;
firePropertyChange(ROW_COUNT, oldValue, newValue);
}
@Override
protected void process(java.util.List<Object[]> chunks) {
for (Object[] row : chunks) {
((javax.swing.table.DefaultTableModel) atable.getModel())
.addRow(row);
}
}
@Override
protected Void doInBackground() throws Exception {
for (int i = 0; i < 1000; i++) {
final int j = i;
Object[] row = new Object[2];
row[0] = "row " + i;
row[1] = Math.round(Math.random() * 100);
publish(row);
setRowCount(j);
Thread.sleep(100);
}
return null;
}
// .....
和
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
final Task task = new Task();
task.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (Task.ROW_COUNT.equals(evt.getPropertyName())) {
int rowCount = task.getRowCount();
// do what you need with rowCount here
}
}
});
task.execute(); // again I usually call this here
}
暂且不说：
答案 1 :(得分：2)
这是正确的，但它并没有从SwingWorker完成批量更新的所有工作中受益，并且让您避免使用这些低级SwingUtilities方法。它还结合了后台进程和UI更新，而不是优雅地将它们分离。
如何将i传递给publish方法：创建一个包含此计数器和行的类：
private static class Update {
private int counter;
private Object[] row;
// constructor, getters omitted for brevity
}
...
class Task extends SwingWorker<Void, Update> {
@Override
protected Void doInBackground() throws Exception {
for (int i = 0; i < 1000; i++) {
Object[] row = new Object[2];
row[0] = "row " + i;
row[1] = Math.round(Math.random() * 100);
publish(new Update(i, row);
Thread.sleep(100);
}
return null;
}
@Override
protected void process(java.util.List<Update> chunks) {
for (Update update : chunks) {
((DefaultTableModel) atable.getModel()).addRow(update.getRow());
}
int lastCounter = chunks.get(chunks.size() - 1).getCounter();
dlf.changeText("Processing " + lastCounter + " of " + 1000);
dlf.setValue(lastCounter);
}
...
}