在 java-9 中，Skins 进入了公共范围，而 Behaviors 则被蒙在鼓里——尽管如此，现在发生了很大变化，现在将 InputMap 用于所有输入绑定。
CellBehaviorBase 安装鼠标绑定，例如：
InputMap.MouseMapping pressedMapping, releasedMapping;
addDefaultMapping(
pressedMapping = new InputMap.MouseMapping(MouseEvent.MOUSE_PRESSED, this::mousePressed),
releasedMapping = new InputMap.MouseMapping(MouseEvent.MOUSE_RELEASED, this::mouseReleased),
new InputMap.MouseMapping(MouseEvent.MOUSE_DRAGGED, this::mouseDragged)
);
现在，一个具体的 XXSkin 会私下安装该行为：
final private BehaviorBase behavior;
public TableCellSkin(TableCell control) {
super(control);
behavior = new TableCellBehavior(control);
....
}
要求是替换 mousePressed 行为（在 jdk9 上下文中）。这个想法是反射性地抓取 super 的字段，处理它的所有映射并安装自定义行为。出于某种我不明白的原因，旧绑定仍然处于活动状态（尽管旧映射是空的！）并且在新绑定之前被调用。
下面是一个可运行的示例：到 mousePressed 的映射被简单地实现为什么都不做，特别是不调用 super。为了查看工作中的旧绑定，我在 CellBehaviorBase.mousePressed 处设置了一个条件调试断点，例如（在 Eclipse 中）：
System.out.println("mousePressed super");
new RuntimeException("whoIsCalling: " + getNode().getClass()).printStackTrace();
return false;
运行调试并单击任何单元格，然后输出为：
mousePressed super
java.lang.RuntimeException: whoIsCalling: class de.swingempire.fx.scene.control.cell.TableCellBehaviorReplace$PlainCustomTableCell
at com.sun.javafx.scene.control.behavior.CellBehaviorBase.mousePressed(CellBehaviorBase.java:169)
at com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
//... lots more of event dispatching
// until finally the output in my custom cell behavior
Feb. 02, 2016 3:14:02 NACHM. de.swingempire.fx.scene.control.cell.TableCellBehaviorReplace$PlainCustomTableCellBehavior mousePressed
INFORMATION: short-circuit super: Bulgarisch
我希望只看到最后一部分，即我的自定义行为的打印输出。感觉就像我从根本上脱离了 - 但无法确定它。想法？
可运行代码（对不起，它的长度，大部分是样板，虽然）：
public class TableCellBehaviorReplace extends Application {
private final ObservableList<Locale> locales =
FXCollections.observableArrayList(Locale.getAvailableLocales());
private Parent getContent() {
TableView<Locale> table = createLocaleTable();
BorderPane content = new BorderPane(table);
return content;
}
private TableView<Locale> createLocaleTable() {
TableView<Locale> table = new TableView<>(locales);
TableColumn<Locale, String> name = new TableColumn<>("Name");
name.setCellValueFactory(new PropertyValueFactory<>("displayName"));
name.setCellFactory(p -> new PlainCustomTableCell<>());
TableColumn<Locale, String> lang = new TableColumn<>("Language");
lang.setCellValueFactory(new PropertyValueFactory<>("displayLanguage"));
lang.setCellFactory(p -> new PlainCustomTableCell<>());
table.getColumns().addAll(name, lang);
return table;
}
/**
* Custom skin that installs custom Behavior. Note: this is dirty!
* Access super's behavior, dispose to get rid off its handlers, install
* custom behavior.
*/
public static class PlainCustomTableCellSkin<S, T> extends TableCellSkin<S, T> {
private BehaviorBase<?> replacedBehavior;
public PlainCustomTableCellSkin(TableCell<S, T> control) {
super(control);
replaceBehavior();
}
private void replaceBehavior() {
BehaviorBase<?> old = (BehaviorBase<?>) invokeGetField(TableCellSkin.class, this, "behavior");
old.dispose();
// at this point, InputMap mappings are empty:
// System.out.println("old mappings: " + old.getInputMap().getMappings().size());
replacedBehavior = new PlainCustomTableCellBehavior<>(getSkinnable());
}
@Override
public void dispose() {
replacedBehavior.dispose();
super.dispose();
}
}
/**
* Custom behavior that's meant to override basic handlers. Here: short-circuit
* mousePressed.
*/
public static class PlainCustomTableCellBehavior<S, T> extends TableCellBehavior<S, T> {
public PlainCustomTableCellBehavior(TableCell<S, T> control) {
super(control);
}
@Override
public void mousePressed(MouseEvent e) {
if (true) {
LOG.info("short-circuit super: " + getNode().getItem());
return;
}
super.mousePressed(e);
}
}
/**
* C&P of default tableCell in TableColumn. Extended to install custom
* skin.
*/
public static class PlainCustomTableCell<S, T> extends TableCell<S, T> {
public PlainCustomTableCell() {
}
@Override protected void updateItem(T item, boolean empty) {
if (item == getItem()) return;
super.updateItem(item, empty);
if (item == null) {
super.setText(null);
super.setGraphic(null);
} else if (item instanceof Node) {
super.setText(null);
super.setGraphic((Node)item);
} else {
super.setText(item.toString());
super.setGraphic(null);
}
}
@Override
protected Skin<?> createDefaultSkin() {
return new PlainCustomTableCellSkin<>(this);
}
}
@Override
public void start(Stage primaryStage) throws Exception {
primaryStage.setScene(new Scene(getContent(), 400, 200));
primaryStage.setTitle(FXUtils.version());
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
/**
* Reflectively access super field.
*/
public static Object invokeGetField(Class source, Object target, String name) {
try {
Field field = source.getDeclaredField(name);
field.setAccessible(true);
return field.get(target);
} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
e.printStackTrace();
}
return null;
}
@SuppressWarnings("unused")
private static final Logger LOG = Logger
.getLogger(TableCellBehaviorReplace.class.getName());
}
编辑
该建议继承自抽象皮肤 XXSkinBase 而不是具体的 XXSkin（然后你可以自由安装你想要的任何行为，伙计 :-) 是非常合理的，应该是第一个选择。在 XX 是 TableCell 的特殊情况下，这目前是不可能的，因为基类包含抽象的包私有方法。此外，还有 XX 没有抽象基础（如 fi ListCell）。