首先看我的GUI:
我试图通过GUI使用MongoDB集合的一些功能(CRUD)。
首先,用户必须从第一个ComboBox中选择现有数据库。当用户选择选项private void jComboBoxDBNamePopupMenuWillBecomeInvisible(javax.swing.event.PopupMenuEvent evt)
时,函数将加载该数据库下的所有集合。这里选择了博客。
然后,用户将从第二个ComboBox的现有集合中选择一个集合。当用户选择集合private void jComboBoxCollectionNamePopupMenuWillBecomeInvisible(javax.swing.event.PopupMenuEvent evt)
时,函数将调用名为refreshTable()
的函数来加载该集合下的所有文档。选择 posts 集合。
从第二个ComboBox中选择选项时,如果所选集合有超过一千个文档,它会要求用户确认他是否确实要加载文档,因为它可能需要时间或可能是内存问题。
确认将通过JOptionPane.showConfirmDialog(...)
完成。
选择收藏帖子时,会显示对话框。但是单击是或否不会给出任何响应。但为什么呢?
图片中的按钮带有红色下划线。
我的public boolean refreshTable()
功能是:
public boolean refreshTable() {
collections = db.getCollection((String) jComboBoxCollectionName.getSelectedItem());
if(collections.count()>1000){
int ret = JOptionPane.showConfirmDialog(this, "The table contains more than thousand row.\nThis may slow down the process and could cause Memory error.Are you sure to continue?","Too Large Collection ("+collections.count()+" Rows)",YES_NO_OPTION, INFORMATION_MESSAGE);
if(ret!=YES_OPTION) return true;
}
//Some irrelevant codes
return false;
}
我在Google上搜索过它并无法解决问题。以下是StackOverflow的一些问题,但我无法从中找出解决方案。
我的项目资源库是here。如果需要你可以看看。
答案 0 :(得分:3)
这可能是因为当你在另一个线程上对它进行动态调用时,应该在Swing的事件派发线程(EDT)上调用JOptionPane
方法。
您应该尝试使用SwingUtilities
实用程序方法调用refreshTable,例如:
SwingUtilities.invokeLater(() -> refreshTable());
答案 1 :(得分:2)
猜测只是因为我们没有你的最小示例程序 - 但是如果在长期运行或CPU密集型代码中调用此JOptionPane,并且如果代码在Swing事件线程上运行,它将冻结Swing事件线程,从而冻结您的GUI。如果您不打算在后台线程中调用长时间运行或CPU密集型代码,则需要这样做,例如使用SwingWorker。
我查看了您的代码,并且您在EDT上启动了GUI:
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
// this will be run on the EDT
new UserInterface().setVisible(true);
}
});
所以杰克的推荐是不必要的,但是您在EDT上进行所有数据库调用并且没有遵循Swing线程规则,这会冻结您的计划,所以我的推荐就是你的需要遵循。您首先需要学习Swing线程的基础知识,因此我建议您查看本教程:Lesson: Concurrency in Swing
你可以使用两个SwingWorkers和两个JPropertyChangeListeners:
SwingWorker<Collections, Void>
。我不知道第一个通用参数应该是什么,除了它应该是您的collections变量的任何类型。该工作人员只需从db.getCollection(selection);
方法返回doInBackground()
。SwingWorker<DefaultTableModel, Void>
并将集合传递到其构造函数中,并根据集合所持有的数据创建DefaultTableModel。SwingWorker.StateValue.DONE
,然后询问用户是否要继续,如果是,这称为第二个SwingWorker。 为了它的价值,我将在下面的代码中沿着这些方向实现某些地方。同样,对我而言,最大的未知数是collections
变量所代表的类型,因此,需要修复第一个SwingWorker的通用参数,并将其从Collections
更改为任何类型。您正在使用:
// change to a void method
public void refreshTable() {
String selection = (String) jComboBoxCollectionName.getSelectedItem();
// SwingWorker to get collections
GetCollectionsWorker getCollectionsWorker = new GetCollectionsWorker(selection);
getCollectionsWorker.addPropertyChangeListener(new GetCollectionsListener());
getCollectionsWorker.execute(); // run worker on background thread
}
// FIXME: Generic type Collections is wrong -- need to use correct type, whatever type collections is
private class GetCollectionsWorker extends SwingWorker<Collections, Void> {
private String selection;
public GetCollectionsWorker(String selection) {
this.selection = selection;
}
@Override
protected Collections doInBackground() throws Exception {
// do database work here in a background thread
return db.getCollection(selection);
}
}
// class that listens for completion of the GetCollectionsWorker worker
class GetCollectionsListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
// all this is done on the EDT
if (SwingWorker.StateValue.DONE == evt.getNewValue()) {
// if worker is done, first get worker from listener
GetCollectionsWorker worker = (GetCollectionsWorker) evt.getSource();
try {
// then extract the data that it's returning
collections = worker.get();
// then offer user option of continuing or not
if (collections.count() > 1000) {
int ret = JOptionPane.showConfirmDialog(UserInterface.this,
"The table contains more than thousand row.\nThis may slow down the process and could cause Memory error.Are you sure to continue?",
"Too Large Collection (" + collections.count() + " Rows)", YES_NO_OPTION, INFORMATION_MESSAGE);
if (ret != YES_OPTION) {
return;
}
}
// our next worker, one to create table model
CreateTableModelWorker createModelWorker = new CreateTableModelWorker(collections);
// be notified when it is done
createModelWorker.addPropertyChangeListener(new CreateModelListener());
createModelWorker.execute(); // run on background thread
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}
// worker to create table model on background thread
class CreateTableModelWorker extends SwingWorker<DefaultTableModel, Void> {
private Collections collections;
public CreateTableModelWorker(Collections collections) {
this.collections = collections;
}
@Override
protected DefaultTableModel doInBackground() throws Exception {
documents = collections.find().into(new ArrayList<Document>());
Set<String> colNames = new HashSet<>();
for (Document doc : documents) {
for (String key : doc.keySet()) {
colNames.add(key);
}
}
columns = colNames.toArray();
Object[][] elements = new Object[documents.size()][columns.length];
int docNo = 0;
for (int i = 0; i < columns.length; i++) {
if (((String) columns[i]).equalsIgnoreCase("_id")) {
_idcol = i;
break;
}
}
for (Document doc : documents) {
for (int i = 0; i < columns.length; i++) {
if (doc.containsKey(columns[i])) {
elements[docNo][i] = doc.get(columns[i]);
}
}
docNo++;
}
DefaultTableModel model = new DefaultTableModel(elements, columns);
return model;
}
}
private class CreateModelListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
// all this is done on the EDT
if (SwingWorker.StateValue.DONE == evt.getNewValue()) {
// if worker is done, first get worker from listener
CreateTableModelWorker worker = (CreateTableModelWorker) evt.getSource();
try {
DefaultTableModel model = worker.get();
jTableResultTable.setModel(model);
UserInterface.this.model = model;
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
}
}
}