Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class InputContext - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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java.awt.im
Class InputContext

java.lang.Object
  |
  +--java.awt.im.InputContext

public class InputContext
extends Object

An InputContext object manages the communication between text editing components and input methods. It dispatches events between them, and forwards requests for information from the input method to the text editing component. It also lets text editing components select input methods by locale.

By default, one InputContext instance is created per Window instance, and this input context is shared by all components within the window's container hierarchy. However, this means that only one text input operation is possible at any one time within a window, and that the text needs to be committed when moving the focus from one text component to another. If this is not desired, text components can create their own input context instances.

Not all platforms and locales support input methods. Where input methods are unavailable, input contexts can still be created and used; the InputContext instance methods return without doing anything (selectLocale returns false).

See Also:: Component.getInputContext(), Component.enableInputMethods(boolean)

Constructor Summary

protected InputContext()
          Constructs an InputContext.

Method Summary

void dispatchEvent(AWTEvent event)
          Dispatches an event to the active input method.

void dispose()
          Disposes of the input context and release the resources used by it.

void endComposition()
          Ends any input composition that may currently be going on in this context.

Object getInputMethodControlObject()
          Returns a control object from the current input method, or null.

static InputContext getInstance()
          Returns a new InputContext instance.

void removeNotify(Component client)
          Notifies the input context that a client component has been removed from its containment hierarchy, or that input method support has been disabled for the component.

boolean selectInputMethod(Locale locale)
          Selects an input method that supports the given locale.

void setCharacterSubsets(Character.Subset[] subsets)
          Sets the subsets of the Unicode character set that input methods of this input context should be allowed to input.

Methods inherited from class java.lang.Object

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

Constructor Detail

InputContext

protected InputContext()

Constructs an InputContext.

Method Detail

getInstance

public static InputContext getInstance()

Returns a new InputContext instance.

selectInputMethod

public boolean selectInputMethod(Locale locale)

Selects an input method that supports the given locale. If the currently selected input method supports the desired locale or if there's no input method available that supports the desired locale, the current input method remains active. Otherwise, an input method is selected that supports text input for the desired locale. Before switching to a different input method, any currently uncommitted text is committed. If the platform does not support input methods or the desired locale, then false is returned.

A text editing component may call this method, for example, when the user changes the insertion point, so that the user can immediately continue typing in the language of the surrounding text.

Parameters:: locale - The desired new locale.
Returns:: Whether the input method that's active after this call supports the desired locale.

setCharacterSubsets

public void setCharacterSubsets(Character.Subset[] subsets)

Sets the subsets of the Unicode character set that input methods of this input context should be allowed to input. Null may be passed in to indicate that all characters are allowed. The initial value is null. The setting applies to the current input method as well as input methods selected after this call is made. However, applications cannot rely on this call having the desired effect, since this setting cannot be passed on to all host input methods - applications still need to apply their own character validation. If the platform does not support input methods, then this method has no effect.

Parameters:: subsets - The subsets of the Unicode character set from which characters may be input

dispatchEvent

public void dispatchEvent(AWTEvent event)

Dispatches an event to the active input method. Called by AWT. If the platform does not support input methods, then the event will never be consumed.

Parameters:: event - The event

removeNotify

public void removeNotify(Component client)

Notifies the input context that a client component has been removed from its containment hierarchy, or that input method support has been disabled for the component. This method is usually called from java.awt.Component.removeNotify() of the client component. Potentially pending input from input methods for this component is discarded.

Parameters:: client - Client component

endComposition

public void endComposition()

Ends any input composition that may currently be going on in this context. Depending on the platform and possibly user preferences, this may commit or delete uncommitted text. Any changes to the text are communicated to the active component using an input method event. If the platform does not support input methods, then this method has no effect.

A text editing component may call this in a variety of situations, for example, when the user moves the insertion point within the text (but outside the composed text), or when the component's text is saved to a file or copied to the clipboard.

dispose

public void dispose()

Disposes of the input context and release the resources used by it. Called by AWT. If the platform does not support input methods, then this method has no effect.

getInputMethodControlObject

public Object getInputMethodControlObject()

Returns a control object from the current input method, or null. A control object provides methods that control the behavior of the input method or obtain information from the input method. The type of the object is an input method specific class. Clients have to compare the result against known input method control object classes and cast to the appropriate class to invoke the methods provided. If the platform does not support input methods, then null is returned.

Returns:: A control object from the current input method, or null.