focus.html

jsf、swing的官方指南

<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Component.html#setFocusable(boolean)">setFocusable(boolean)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Component.html#isFocusable()">isFocusable()</a></td>
<td>Set or get the focusable state of the component.
A component must be focusable in order to gain the focus.
When a component has been removed from the focus cycle with
<code>setFocusable(false)</code>, it can no longer be navigated
with the keyboard. We prefer <code>setRequestFocusEnabled</code>
so that your program can be run by users employing
<a href=access.html>assistive technologies</a>.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Component.html#requestFocusInWindow()">requestFocusInWindow()</a></td>
<td>Request that this component gets the focus.
    The component's window must be the current focused window.
    A subclass of <code>JComponent</code> must be visible,
    enabled, and focusable, and have an input map for this
    request to be granted. Even so, it shouldn't be
    assumed that the component has focus until it
    fires a <code>FOCUS_GAINED</code> event.
    This method is preferred to <code>requestFocus</code>,
    which is platform dependent.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#setFocusTraversalKeys(int, java.util.Set)">setFocusTraversalKeys(int, Set)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#getFocusTraversalKeys(int)">getFocusTraversalKeys(int)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#areFocusTraversalKeysSet(int)">areFocusTraversalKeysSet(int)</a><br>(<em>in <code>java.awt.Container</code></em>)
</td>
<td>
Set or get the focus traversal keys for a particular
direction or determine whether any focus traversal keys have
been explicitly set on this container.  If no focus traversal
keys have been set, they are inherited from an ancestor or
from the keyboard focus manager.  Focus traversal keys
can be set for the following directions: 
<code>KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS</code>,
<code>KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS</code>
<code>KeyboardFocusManager.UP_CYCLE_TRAVERSAL_KEYS</code>, or
<code>KeyboardFocusManager.DOWN_CYCLE_TRAVERSAL_KEYS</code>.
If you set the <code>UP_CYCLE_TRAVERSAL_KEYS</code> or the
<code>DOWN_CYCLE_TRAVERSAL_KEYS</code>, you must also invoke 
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SortingFocusTraversalPolicy.html#setImplicitDownCycleTraversal(boolean)"><code>setImplicitDownCycleTraversal(false)</code></a> on the focus traversal policy.
</td>
</tr>

</table>

<p align=center><a name="focustraversal">Creating and Using a Custom
          FocusTraversalPolicy</a>
<p><em>All of this API was introduced in release 1.4. Unless
   otherwise specified, each method is defined in the
   <code>FocusTraversalPolicy</code> interface.</em>
<table border=1>
<tr>
<th align=left>Class or Method</th>
<th align=left>Purpose</th>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/LayoutFocusTraversalPolicy.html">LayoutFocusTraversalPolicy</a></td>
<td>The class that, by default, determines the focus traversal
    policy for Swing components.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/LayoutFocusTraversalPolicy.html#getComponentAfter(java.awt.Container, java.awt.Component)">getComponentAfter(Container, Component)</a></td>
<td>Given the component passed in,
    return the component that should next have the focus.
</td>
</tr>
    
<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/LayoutFocusTraversalPolicy.html#getComponentBefore(java.awt.Container, java.awt.Component)">getComponentBefore(Container, Component)</a></td>
<td>Given the component passed in,
    return the component that should have the focus before
    this one. This is used for backwards tabbing.
</td>
</tr>
    
<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SortingFocusTraversalPolicy.html#getDefaultComponent(java.awt.Container)">getDefaultComponent(Container)</a><br>(<em>in <code>javax.swing.SortingFocusTraversalPolicy</code>)</em>
</td>
<td>Return the component that should have the default focus.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/LayoutFocusTraversalPolicy.html#getFirstComponent(java.awt.Container)">getFirstComponent(Container)</a></td>
<td>Return the first component in the traversal cycle.
</td>
</tr>
    
<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/InternalFrameFocusTraversalPolicy.html#getInitialComponent(java.awt.Container)">getInitialComponent(Container)</a></td>
<td>Return the component that should
    receive the focus when a window is made
    visible for the first time.
</td>
</tr>
    
<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/LayoutFocusTraversalPolicy.html#getLastComponent(java.awt.Container)">getLastComponent(Container)</a></td>
<td>Return the last component in the
    traversal cycle.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#setFocusTraversalPolicy(java.awt.FocusTraversalPolicy)">setFocusTraversalPolicy(FocusTraversalPolicy)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#getFocusTraversalPolicy()">getFocusTraversalPolicy(FocusTraversalPolicy)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/Container.html#isFocusTraversalPolicySet()">isFocusTraversalPolicySet()</a><br>(<em>in <code>java.awt.Container</code></em>)
</td>
<td>Set or get the focus traversal policy or
    determine if one has been set. Note that setting a focus
    traversal policy on a container that is not the focus cycle
    root may have no apparent effect.
    A value of <code>null</code> means that a policy has
    not been explicitly set. If no policy has been set
    one is inherited from the parent focus cycle root.
</td>
</tr>
</table>

<p align=center><a name="inputverificationapi">Input Verification API</a>
<p><em>All of this API was introduced in release 1.3.</em>
<table border=1>
<tr>
<th align=left>Class or Method</th>
<th align=left>Purpose</th>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/InputVerifier.html">InputVerifier</a></td>
<td>Abstract class that allows input validation via the focus
    mechanism. When an attempt is made to shift the focus from a component
    containing an input verifier, the focus is not relinquished
    until the verifier is satisfied.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/InputVerifier.html#shouldYieldFocus(javax.swing.JComponent)">shouldYieldFocus(JComponent)</a><br><em>(in <code>InputVerifier</code>)</em>
</td>
<td>When a component has an input verifier, this method is
    called by the system to determine whether the focus can
    leave this component.  This method may cause side effects, 
    such as bringing up a dialog. If this method returns
    false, the focus remains on the component passed in
    to the method.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/InputVerifier.html#verify(javax.swing.JComponent)">verify(JComponent)</a><br><em>(in <code>InputVerifier</code>)</em>
</td>
<td>You need to override this method to check that
    the component's input is valid. It should return
    true if valid, otherwise return false.
    This method should not cause any side effects,
    such as bringing up a dialog.  This method is
    called by <code>shouldYieldFocus</code>.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JComponent.html#setInputVerifier(javax.swing.InputVerifier)">setInputVerifier(inputVerifier)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JComponent.html#getInputVerifier()">getInputVerifier()</a><br><em>(in <code>JComponent</code>)</em>
</td>
<td>Set or get the input verifier assigned to the
    component. By default, components have no input
verifier.
</td>
</tr>

<tr>
<td>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JComponent.html#setVerifyInputWhenFocusTarget(boolean)">setVerifyInputWhenFocusTarget(boolean)</a><br>
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/JComponent.html#getVerifyInputWhenFocusTarget()">getVerifyInputWhenFocusTarget()</a><br><em>(in <code>JComponent</code>)</em>
</td>
<td>Set or get whether the input verifier for the current focus owner
    is called before this component requests the focus.
    The default is true.  This should be set to false for 
    components, such as a Cancel button or a scroll
    bar, that should receive the focus even if input is invalid.
</td>
</tr>

</table>


<p align=center><a name="properties">KeyboardFocusManager Properties</a>
<p>This table defines the bound properties for
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/KeyboardFocusManager.html"><code>KeyboardFocusManager</code></a>. A listener can be registered for these properties by calling
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/java/awt/KeyboardFocusManager.html#addPropertyChangeListener(java.beans.PropertyChangeListener)"><code>addPropertyChangeListener</code></a>.
<p><em>All of this API was introduced in release 1.4.</em>
<table border=1>
<tr>
<th align=left>Property</th>
<th align=left>Purpose</th>
</tr>

<tr>
<td>focusOwner</td>
<td>The component that currently receives
key events.</td>
</tr>

<tr>
<td>permanentFocusOwner</td>
<td>The component that most recently received a
permanent <code>FOCUS_GAINED</code> event.
Typically the same as <code>focusOwner</code>, unless
a temporary focus change is currently in effect. </td>
</tr>

<tr>
<td>focusedWindow</td>
<td>The window that is or that contains the focus owner.</td>
</tr>

<tr>
<td>activeWindow</td>
<td>Must always be either a <code>Frame</code> or a
<code>Dialog</code>.  The active window is either the
focused window, or the first frame or dialog that is an
owner of the focused window.</td>
</tr>

<tr>
<td>defaultFocusTraversalPolicy</td>
<td>The default focus traversal policy.  This can be
set by the <code>Container</code>
<code>setFocusTraversalPolicy</code> method.</td>
</tr>

<tr>
<td>forwardDefaultFocusTraversalKeys</td>
<td>The set of default focus keys for a forward traversal.
For multi-line text components, this defaults to Control-Tab. 
For all other components, this defaults to Tab
and Control-Tab.
</td>
</tr>

<tr>
<td>backwardDefaultFocusTraversalKeys</td>
<td>The set of default focus keys for a backwards traversal.
For multi-line text components this defaults to Control-Shift-Tab.
For all other components this defaults to Shift-Tab
and Control-Shift-Tab.
</td>
</tr>

<tr>
<td>upCycleDefaultFocusTraversalKeys</td>
<td>The set of default focus keys for an up cycle.
    These are null, by default, for Swing components.
    If you set these keys on the <code>KeyboardFocusManager</code>,
    or if you set the <code>downCycleFocusTraversalKeys</code> on a focus
    cycle root, you must also invoke
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SortingFocusTraversalPolicy.html#setImplicitDownCycleTraversal(boolean)"><code>setImplicitDownCycleTraversal(false)</code></a> on the focus traversal policy.
</td>
</tr>

<tr>
<td>downCycleDefaultFocusTraversalKeys</td>
<td>The set of default focus keys for a down cycle.
    These are null, by default, for Swing components.
    If you set these keys on the <code>KeyboardFocusManager</code>,
    or if you set the <code>upCycleFocusTraversalKeys</code> on a focus
    cycle root, you must also invoke
<a class="APILink" target="_blank" href="http://java.sun.com/javase/6/docs/api/javax/swing/SortingFocusTraversalPolicy.html#setImplicitDownCycleTraversal(boolean)"><code>setImplicitDownCycleTraversal(false)</code></a> on the focus traversal policy.
</td>
</tr>

<tr>
<td>currentFocusCycleRoot</td>
<td>The container that is the current focus cycle root.</td>
</tr>

</tr>
</table>

</blockquote>

<h3>
<a name="eg">Examples that Use Focus</a>
</h3>
<blockquote>
The following table lists examples that
manipulate the focus:
<p>
<table>
<tr valign = top>
<th align=left> Example</th>
<th align=left> Where Described</th>
<th align=left> Notes</th>
</tr>

<tr valign = top>
<td> <a href="examples/index.html#FocusConceptsDemo">
     <code>FocusConceptsDemo</code></a>
</td>
<td> This section</td>
<td> Demonstrates basic default focus behavior.
</td>
</tr>

<tr valign = top>
<td> <a href="examples/index.html#FocusTraversalDemo">
     <code>FocusTraversalDemo</code></a>
</td>
<td> This section</td>
<td> Demonstrates how to override the default focus order.
</td>
</tr>

<tr valign = top>
<td> <a href="examples/index.html#TrackFocusDemo">
     <code>TrackFocusDemo</code></a>
</td>
<td> This section</td>
<td> Demonstrates how to use a <code>PropertyChangeListener</code>
     to track the focus owner. Also implements a custom focusable
     component.
</td>
</tr>

<tr valign = top>
<td> <a href="examples/index.html#InputVerificationDemo">
     <code>InputVerificationDemo</code></a>
</td>
<td> This section</td>
<td> Demonstrates how to implement an <code>InputVerifier</code>
     to validate user input.
</td>
</tr>

<tr valign = top>
<td> <a href="examples/index.html#InputVerificationDialogDemo">
     <code>InputVerificationDialogDemo</code></a>
</td>
<td> This section</td>
<td> Demonstrates how to implement an <code>InputVerifier</code>
     that puts up a dialog when user input is invalid.
</td>
</tr>

<tr valign = top>
<td>
<a class="TutorialLink" target="_top" href="../events/examples/index.html#FocusEventDemo">FocusEventDemo</a><td>
<a class="TutorialLink" target="_top" href="../events/focuslistener.html">How to Write a Focus Listener</a></td>
<td> Reports all focus events that occur on several components
     to demonstrate the circumstances under which focus events are fired.
</td>
</tr>

</table>

        </blockquote>
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