java - 如何向 ComboBoxTableCell 添加键盘编辑支持

Question

ComboBoxTableCell 允许在编辑模式下将 ComboBox 添加到 TableCell。如果 comboBox.show() 被调用(例如，弹出窗口正在显示)，comboBox 会按预期对向下箭头和向上箭头键使用react，并结束编辑模式一旦进入被击中。我只想使用键盘控制编辑。我找不到使用键盘调用“comboBox.show()”的方法。

直到现在，我尝试使用 setOnKeyPressed 将回调添加到 ComboBoxTableCell(在通过工厂方法创建期间)或 ComboBox(通过使用 ComboBoxTableCell.getGraphic())。回调调用了 ComboBox.show() 来打开弹出窗口，但它们没有被调用(通过打印到回调中的 System.out 来验证)。

actColumn.setCellFactory(
        new Callback<TableColumn<S,Object>, TableCell<S,Object>>() {
    private ObservableList<Object> list=optionList;

    @SuppressWarnings("unchecked")
    @Override
    public TableCell<S, Object> call(TableColumn<S, Object> param) {
        final ComboBoxTableCell<S,Object> cell=
                new ComboBoxTableCell<S,Object>(list);
        cell.setConverter((StringConverter<Object>) converter);
        cell.setOnKeyPressed(event -> {
            cell.startEdit();

            Node node=cell.getGraphic();
            System.out.println(node);
            if(node instanceof ComboBox) {
                System.out.println("Hit Key.");
                final ComboBox<?> box=(ComboBox<?>) node;
                box.show();
            }
        });
        //We have to forcefully fill the combobox member and set the
        //graphic, because the cell does not init the ComboBox in 
                    //its constructor
        Platform.runLater(new Runnable() {
            @Override public void run() {
                cell.startEdit();

                Node node=cell.getGraphic();
                if(node instanceof ComboBox) {
                    ComboBox<?> box=(ComboBox<?>) node;
                    //Now we should have the combobox for this cell
                    box.setOnKeyPressed(event -> {
                        System.out.println("Hit Key.");
                        if(event.getCode()==KeyCode.DOWN) {
                            System.out.println("Hit Arrow.");
                            box.show();
                        }
                    });
                }

                //Stop editing again
                cell.cancelEdit();
             }
        });

        return cell;
    }
});

除了这段代码很奇怪之外，当在单元格的编辑模式下按下一个键时，处理程序不会被调用(或者至少我没有得到任何输出)。

我希望能够选择一个 ComboBoxTableCell，按下回车键(可能还有一个额外的键)，然后内部 ComboBox 的弹出窗口应该在没有任何交互的情况下出现鼠标完成。

Answer 1

您可以子类化 ComboBoxTableCell 以添加您想要的行为。这是一个概念验证:

import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.collections.ObservableList;
import javafx.event.EventHandler;
import javafx.scene.control.ComboBox;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.ComboBoxTableCell;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.util.StringConverter;

public class AutoShowComboBoxTableCell<S, T> extends ComboBoxTableCell<S, T> {

    /* 
     * May want to provide alternate constructors and static methods similar to
     * the ComboBoxTableCell class (i.e. the superclass).
     */

    private boolean enterPressed;

    public AutoShowComboBoxTableCell(StringConverter<T> converter, ObservableList<T> values) {
        super(converter, values);
        getStyleClass().add("auto-show-combo-box-table-cell");

        // Assumes TableView property is set only once (valid assumption?)
        tableViewProperty().addListener(new InvalidationListener() {
            @Override
            public void invalidated(Observable observable) {
                // Need to know if editing was started by the user pressing
                // the ENTER key (see #startEdit())
                EventHandler<KeyEvent> filter = event -> {
                    if (event.getCode() == KeyCode.ENTER) {
                        enterPressed = event.getEventType() == KeyEvent.KEY_PRESSED;
                    }
                };
                // Possible memory leak? Consider using WeakEventHandler (read docs)
                getTableView().addEventFilter(KeyEvent.KEY_PRESSED, filter);
                getTableView().addEventFilter(KeyEvent.KEY_RELEASED, filter);
                observable.removeListener(this);
            }
        });
    }

    @Override
    public void startEdit() {
        if (isEditing()) return;

        super.startEdit();
        if (isEditing()) {
            if (enterPressed) {
                // Cell was put into edit mode by the user pressing ENTER. This causes
                // problems since *releasing* ENTER while the ComboBox has the focus
                // results in the value being committed; this leads to the current value
                // being committed *immediately* after entering edit mode—not what we want. 
                // To fix that we consume the first ENTER-released event and then let all
                // subsequent events through (by removing the event filter).
                addEventFilter(KeyEvent.KEY_RELEASED, new EventHandler<>() {
                    @Override public void handle(KeyEvent event) {
                        if (event.getCode() == KeyCode.ENTER) {
                            event.consume();
                            removeEventFilter(KeyEvent.KEY_RELEASED, this);
                        }
                    }
                });
            }
            ComboBox<?> comboBox = (ComboBox<?>) getGraphic();
            comboBox.requestFocus(); // Needed to allow releasing ENTER to commit the value
            comboBox.show();
        }
    }

    @Override
    public void cancelEdit() {
        if (isEditing()) {
            super.cancelEdit();
            requestTableViewFocus();
        }
    }

    @Override
    public void commitEdit(T newValue) {
        if (isEditing()) {
            super.commitEdit(newValue);
            requestTableViewFocus();
        }
    }

    // Allows user to keep navigating the table via the keyboard
    private void requestTableViewFocus() {
        TableView<S> tableView = getTableView();
        if (tableView != null) {
            tableView.requestFocus();
        }
    }

}

注意:以上内容使用了实现细节的知识，包括在编辑开始时将图形设置为 ComboBox 的事实以及导致编辑要提交。实现细节如有更改，恕不另行通知。