DefaultKeyboardFocusManager (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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Java™ Platform
Standard Ed. 6

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java.awt
Class DefaultKeyboardFocusManager

java.lang.Object
  java.awt.KeyboardFocusManager
      java.awt.DefaultKeyboardFocusManager

All Implemented Interfaces:: KeyEventDispatcher, KeyEventPostProcessor

Direct Known Subclasses:: FocusManager

public class DefaultKeyboardFocusManager
extends KeyboardFocusManager
extends KeyboardFocusManager

The default KeyboardFocusManager for AWT applications. Focus traversal is done in response to a Component's focus traversal keys, and using a Container's FocusTraversalPolicy.

Please see How to Use the Focus Subsystem, a section in The Java Tutorial, and the Focus Specification for more information.

Since:: 1.4
See Also:: FocusTraversalPolicy, Component.setFocusTraversalKeys(int, java.util.Set), Component.getFocusTraversalKeys(int)

Field Summary

Fields inherited from class java.awt.KeyboardFocusManager

BACKWARD_TRAVERSAL_KEYS, DOWN_CYCLE_TRAVERSAL_KEYS, FORWARD_TRAVERSAL_KEYS, UP_CYCLE_TRAVERSAL_KEYS

Constructor Summary

DefaultKeyboardFocusManager()


Method Summary

protected void dequeueKeyEvents(long after, Component untilFocused)
          Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to enqueueKeyEvents with the same timestamp and Component.

protected void discardKeyEvents(Component comp)
          Discards all KeyEvents which were enqueued because of one or more calls to enqueueKeyEvents with the specified Component, or one of its descendants.

boolean dispatchEvent(AWTEvent e)
          This method is called by the AWT event dispatcher requesting that the current KeyboardFocusManager dispatch the specified event on its behalf.

boolean dispatchKeyEvent(KeyEvent e)
          Called by dispatchEvent if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered.

void downFocusCycle(Container aContainer)
          Moves the focus down one focus traversal cycle.

protected void enqueueKeyEvents(long after, Component untilFocused)
          Delays dispatching of KeyEvents until the specified Component becomes the focus owner.

void focusNextComponent(Component aComponent)
          Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.

void focusPreviousComponent(Component aComponent)
          Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.

boolean postProcessKeyEvent(KeyEvent e)
          This method will be called by dispatchKeyEvent.

void processKeyEvent(Component focusedComponent, KeyEvent e)
          This method initiates a focus traversal operation if and only if the KeyEvent represents a focus traversal key for the specified focusedComponent.

void upFocusCycle(Component aComponent)
          Moves the focus up one focus traversal cycle.

Methods inherited from class java.awt.KeyboardFocusManager

addKeyEventDispatcher, addKeyEventPostProcessor, addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, clearGlobalFocusOwner, downFocusCycle, firePropertyChange, fireVetoableChange, focusNextComponent, focusPreviousComponent, getActiveWindow, getCurrentFocusCycleRoot, getCurrentKeyboardFocusManager, getDefaultFocusTraversalKeys, getDefaultFocusTraversalPolicy, getFocusedWindow, getFocusOwner, getGlobalActiveWindow, getGlobalCurrentFocusCycleRoot, getGlobalFocusedWindow, getGlobalFocusOwner, getGlobalPermanentFocusOwner, getKeyEventDispatchers, getKeyEventPostProcessors, getPermanentFocusOwner, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, redispatchEvent, removeKeyEventDispatcher, removeKeyEventPostProcessor, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener, setCurrentKeyboardFocusManager, setDefaultFocusTraversalKeys, setDefaultFocusTraversalPolicy, setGlobalActiveWindow, setGlobalCurrentFocusCycleRoot, setGlobalFocusedWindow, setGlobalFocusOwner, setGlobalPermanentFocusOwner, upFocusCycle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Fields inherited from class java.awt.KeyboardFocusManager
`BACKWARD_TRAVERSAL_KEYS, DOWN_CYCLE_TRAVERSAL_KEYS, FORWARD_TRAVERSAL_KEYS, UP_CYCLE_TRAVERSAL_KEYS`

Constructor Summary
`DefaultKeyboardFocusManager()`

Method Summary
`protected void`	`dequeueKeyEvents(long after, Component untilFocused)` Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to `enqueueKeyEvents` with the same timestamp and Component.
`protected void`	`discardKeyEvents(Component comp)` Discards all KeyEvents which were enqueued because of one or more calls to `enqueueKeyEvents` with the specified Component, or one of its descendants.
`boolean`	`dispatchEvent(AWTEvent e)` This method is called by the AWT event dispatcher requesting that the current KeyboardFocusManager dispatch the specified event on its behalf.
`boolean`	`dispatchKeyEvent(KeyEvent e)` Called by `dispatchEvent` if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered.
`void`	`downFocusCycle(Container aContainer)` Moves the focus down one focus traversal cycle.
`protected void`	`enqueueKeyEvents(long after, Component untilFocused)` Delays dispatching of KeyEvents until the specified Component becomes the focus owner.
`void`	`focusNextComponent(Component aComponent)` Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.
`void`	`focusPreviousComponent(Component aComponent)` Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.
`boolean`	`postProcessKeyEvent(KeyEvent e)` This method will be called by `dispatchKeyEvent`.
`void`	`processKeyEvent(Component focusedComponent, KeyEvent e)` This method initiates a focus traversal operation if and only if the KeyEvent represents a focus traversal key for the specified focusedComponent.
`void`	`upFocusCycle(Component aComponent)` Moves the focus up one focus traversal cycle.

Methods inherited from class java.awt.KeyboardFocusManager
addKeyEventDispatcher, addKeyEventPostProcessor, addPropertyChangeListener, addPropertyChangeListener, addVetoableChangeListener, addVetoableChangeListener, clearGlobalFocusOwner, downFocusCycle, firePropertyChange, fireVetoableChange, focusNextComponent, focusPreviousComponent, getActiveWindow, getCurrentFocusCycleRoot, getCurrentKeyboardFocusManager, getDefaultFocusTraversalKeys, getDefaultFocusTraversalPolicy, getFocusedWindow, getFocusOwner, getGlobalActiveWindow, getGlobalCurrentFocusCycleRoot, getGlobalFocusedWindow, getGlobalFocusOwner, getGlobalPermanentFocusOwner, getKeyEventDispatchers, getKeyEventPostProcessors, getPermanentFocusOwner, getPropertyChangeListeners, getPropertyChangeListeners, getVetoableChangeListeners, getVetoableChangeListeners, redispatchEvent, removeKeyEventDispatcher, removeKeyEventPostProcessor, removePropertyChangeListener, removePropertyChangeListener, removeVetoableChangeListener, removeVetoableChangeListener, setCurrentKeyboardFocusManager, setDefaultFocusTraversalKeys, setDefaultFocusTraversalPolicy, setGlobalActiveWindow, setGlobalCurrentFocusCycleRoot, setGlobalFocusedWindow, setGlobalFocusOwner, setGlobalPermanentFocusOwner, upFocusCycle

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

DefaultKeyboardFocusManager

public DefaultKeyboardFocusManager()

Method Detail

dispatchEvent

public boolean dispatchEvent(AWTEvent e)

This method is called by the AWT event dispatcher requesting that the current KeyboardFocusManager dispatch the specified event on its behalf. DefaultKeyboardFocusManagers dispatch all FocusEvents, all WindowEvents related to focus, and all KeyEvents. These events are dispatched based on the KeyboardFocusManager's notion of the focus owner and the focused and active Windows, sometimes overriding the source of the specified AWTEvent. If this method returns false, then the AWT event dispatcher will attempt to dispatch the event itself.

Specified by:: dispatchEvent in class KeyboardFocusManager

Parameters:: e - the AWTEvent to be dispatched
Returns:: true if this method dispatched the event; false otherwise
See Also:: KeyboardFocusManager.redispatchEvent(java.awt.Component, java.awt.AWTEvent), KeyboardFocusManager.dispatchKeyEvent(java.awt.event.KeyEvent)

dispatchKeyEvent

public boolean dispatchKeyEvent(KeyEvent e)

Called by dispatchEvent if no other KeyEventDispatcher in the dispatcher chain dispatched the KeyEvent, or if no other KeyEventDispatchers are registered. If the event has not been consumed, its target is enabled, and the focus owner is not null, this method dispatches the event to its target. This method will also subsequently dispatch the event to all registered KeyEventPostProcessors. After all this operations are finished, the event is passed to peers for processing.

In all cases, this method returns true, since DefaultKeyboardFocusManager is designed so that neither dispatchEvent, nor the AWT event dispatcher, should take further action on the event in any situation.

Specified by:: dispatchKeyEvent in interface KeyEventDispatcher
Specified by:: dispatchKeyEvent in class KeyboardFocusManager

Parameters:: e - the KeyEvent to be dispatched
Returns:: true
See Also:: Component.dispatchEvent(java.awt.AWTEvent)

postProcessKeyEvent

public boolean postProcessKeyEvent(KeyEvent e)

This method will be called by dispatchKeyEvent. It will handle any unconsumed KeyEvents that map to an AWT MenuShortcut by consuming the event and activating the shortcut.

Specified by:: postProcessKeyEvent in interface KeyEventPostProcessor
Specified by:: postProcessKeyEvent in class KeyboardFocusManager

Parameters:: e - the KeyEvent to post-process
Returns:: true
See Also:: dispatchKeyEvent(java.awt.event.KeyEvent), MenuShortcut

processKeyEvent

public void processKeyEvent(Component focusedComponent,
                            KeyEvent e)

This method initiates a focus traversal operation if and only if the KeyEvent represents a focus traversal key for the specified focusedComponent. It is expected that focusedComponent is the current focus owner, although this need not be the case. If it is not, focus traversal will nevertheless proceed as if focusedComponent were the focus owner.

Specified by:: processKeyEvent in class KeyboardFocusManager

Parameters:: focusedComponent - the Component that is the basis for a focus traversal operation if the specified event represents a focus traversal key for the Component; e - the event that may represent a focus traversal key

enqueueKeyEvents

protected void enqueueKeyEvents(long after,
                                Component untilFocused)

Delays dispatching of KeyEvents until the specified Component becomes the focus owner. KeyEvents with timestamps later than the specified timestamp will be enqueued until the specified Component receives a FOCUS_GAINED event, or the AWT cancels the delay request by invoking dequeueKeyEvents or discardKeyEvents.

Specified by:: enqueueKeyEvents in class KeyboardFocusManager

Parameters:: after - timestamp of current event, or the current, system time if the current event has no timestamp, or the AWT cannot determine which event is currently being handled; untilFocused - Component which will receive a FOCUS_GAINED event before any pending KeyEvents
See Also:: dequeueKeyEvents(long, java.awt.Component), discardKeyEvents(java.awt.Component)

dequeueKeyEvents

protected void dequeueKeyEvents(long after,
                                Component untilFocused)

Releases for normal dispatching to the current focus owner all KeyEvents which were enqueued because of a call to enqueueKeyEvents with the same timestamp and Component. If the given timestamp is less than zero, the outstanding enqueue request for the given Component with the oldest timestamp (if any) should be cancelled.

Specified by:: dequeueKeyEvents in class KeyboardFocusManager

Parameters:: after - the timestamp specified in the call to enqueueKeyEvents, or any value < 0; untilFocused - the Component specified in the call to enqueueKeyEvents
See Also:: enqueueKeyEvents(long, java.awt.Component), discardKeyEvents(java.awt.Component)

discardKeyEvents

protected void discardKeyEvents(Component comp)

Discards all KeyEvents which were enqueued because of one or more calls to enqueueKeyEvents with the specified Component, or one of its descendants.

Specified by:: discardKeyEvents in class KeyboardFocusManager

Parameters:: comp - the Component specified in one or more calls to enqueueKeyEvents, or a parent of such a Component
See Also:: enqueueKeyEvents(long, java.awt.Component), dequeueKeyEvents(long, java.awt.Component)

focusPreviousComponent

public void focusPreviousComponent(Component aComponent)

Focuses the Component before aComponent, typically based on a FocusTraversalPolicy.

Specified by:: focusPreviousComponent in class KeyboardFocusManager

Parameters:: aComponent - the Component that is the basis for the focus traversal operation
See Also:: FocusTraversalPolicy, Component.transferFocusBackward()

focusNextComponent

public void focusNextComponent(Component aComponent)

Focuses the Component after aComponent, typically based on a FocusTraversalPolicy.

Specified by:: focusNextComponent in class KeyboardFocusManager

Parameters:: aComponent - the Component that is the basis for the focus traversal operation
See Also:: FocusTraversalPolicy, Component.transferFocus()

upFocusCycle

public void upFocusCycle(Component aComponent)

Moves the focus up one focus traversal cycle. Typically, the focus owner is set to aComponent's focus cycle root, and the current focus cycle root is set to the new focus owner's focus cycle root. If, however, aComponent's focus cycle root is a Window, then the focus owner is set to the focus cycle root's default Component to focus, and the current focus cycle root is unchanged.

Specified by:: upFocusCycle in class KeyboardFocusManager

Parameters:: aComponent - the Component that is the basis for the focus traversal operation
See Also:: Component.transferFocusUpCycle()

downFocusCycle

public void downFocusCycle(Container aContainer)

Moves the focus down one focus traversal cycle. If aContainer is a focus cycle root, then the focus owner is set to aContainer's default Component to focus, and the current focus cycle root is set to aContainer. If aContainer is not a focus cycle root, then no focus traversal operation occurs.

Specified by:: downFocusCycle in class KeyboardFocusManager

Parameters:: aContainer - the Container that is the basis for the focus traversal operation
See Also:: Container.transferFocusDownCycle()