JDK8/Java8源码在线阅读
/*
* Copyright (c) 1995, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.awt;
import java.awt.peer.MenuComponentPeer;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.io.ObjectInputStream;
import sun.awt.AppContext;
import sun.awt.AWTAccessor;
import javax.accessibility.*;
import java.security.AccessControlContext;
import java.security.AccessController;
/**
* The abstract class <code>MenuComponent</code> is the superclass
* of all menu-related components. In this respect, the class
* <code>MenuComponent</code> is analogous to the abstract superclass
* <code>Component</code> for AWT components.
* <p>
* Menu components receive and process AWT events, just as components do,
* through the method <code>processEvent</code>.
*
* @author Arthur van Hoff
* @since JDK1.0
*/
public abstract class MenuComponent implements java.io.Serializable {
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
}
transient MenuComponentPeer peer;
transient MenuContainer parent;
/**
* The <code>AppContext</code> of the <code>MenuComponent</code>.
* This is set in the constructor and never changes.
*/
transient AppContext appContext;
/**
* The menu component's font. This value can be
* <code>null</code> at which point a default will be used.
* This defaults to <code>null</code>.
*
* @serial
* @see #setFont(Font)
* @see #getFont()
*/
Font font;
/**
* The menu component's name, which defaults to <code>null</code>.
* @serial
* @see #getName()
* @see #setName(String)
*/
private String name;
/**
* A variable to indicate whether a name is explicitly set.
* If <code>true</code> the name will be set explicitly.
* This defaults to <code>false</code>.
* @serial
* @see #setName(String)
*/
private boolean nameExplicitlySet = false;
/**
* Defaults to <code>false</code>.
* @serial
* @see #dispatchEvent(AWTEvent)
*/
boolean newEventsOnly = false;
/*
* The menu's AccessControlContext.
*/
private transient volatile AccessControlContext acc =
AccessController.getContext();
/*
* Returns the acc this menu component was constructed with.
*/
final AccessControlContext getAccessControlContext() {
if (acc == null) {
throw new SecurityException(
"MenuComponent is missing AccessControlContext");
}
return acc;
}
/*
* Internal constants for serialization.
*/
final static String actionListenerK = Component.actionListenerK;
final static String itemListenerK = Component.itemListenerK;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -4536902356223894379L;
static {
AWTAccessor.setMenuComponentAccessor(
new AWTAccessor.MenuComponentAccessor() {
public AppContext getAppContext(MenuComponent menuComp) {
return menuComp.appContext;
}
public void setAppContext(MenuComponent menuComp,
AppContext appContext) {
menuComp.appContext = appContext;
}
public MenuContainer getParent(MenuComponent menuComp) {
return menuComp.parent;
}
public Font getFont_NoClientCode(MenuComponent menuComp) {
return menuComp.getFont_NoClientCode();
}
});
}
/**
* Creates a <code>MenuComponent</code>.
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless</code>
* returns <code>true</code>
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public MenuComponent() throws HeadlessException {
GraphicsEnvironment.checkHeadless();
appContext = AppContext.getAppContext();
}
/**
* Constructs a name for this <code>MenuComponent</code>.
* Called by <code>getName</code> when the name is <code>null</code>.
* @return a name for this <code>MenuComponent</code>
*/
String constructComponentName() {
return null; // For strict compliance with prior platform versions, a MenuComponent
// that doesn't set its name should return null from
// getName()
}
/**
* Gets the name of the menu component.
* @return the name of the menu component
* @see java.awt.MenuComponent#setName(java.lang.String)
* @since JDK1.1
*/
public String getName() {
if (name == null && !nameExplicitlySet) {
synchronized(this) {
if (name == null && !nameExplicitlySet)
name = constructComponentName();
}
}
return name;
}
/**
* Sets the name of the component to the specified string.
* @param name the name of the menu component
* @see java.awt.MenuComponent#getName
* @since JDK1.1
*/
public void setName(String name) {
synchronized(this) {
this.name = name;
nameExplicitlySet = true;
}
}
/**
* Returns the parent container for this menu component.
* @return the menu component containing this menu component,
* or <code>null</code> if this menu component
* is the outermost component, the menu bar itself
*/
public MenuContainer getParent() {
return getParent_NoClientCode();
}
// NOTE: This method may be called by privileged threads.
// This functionality is implemented in a package-private method
// to insure that it cannot be overridden by client subclasses.
// DO NOT INVOKE CLIENT CODE ON THIS THREAD!
final MenuContainer getParent_NoClientCode() {
return parent;
}
/**
* @deprecated As of JDK version 1.1,
* programs should not directly manipulate peers.
*/
@Deprecated
public MenuComponentPeer getPeer() {
return peer;
}
/**
* Gets the font used for this menu component.
* @return the font used in this menu component, if there is one;
* <code>null</code> otherwise
* @see java.awt.MenuComponent#setFont
*/
public Font getFont() {
Font font = this.font;
if (font != null) {
return font;
}
MenuContainer parent = this.parent;
if (parent != null) {
return parent.getFont();
}
return null;
}
// NOTE: This method may be called by privileged threads.
// This functionality is implemented in a package-private method
// to insure that it cannot be overridden by client subclasses.
// DO NOT INVOKE CLIENT CODE ON THIS THREAD!
final Font getFont_NoClientCode() {
Font font = this.font;
if (font != null) {
return font;
}
// The MenuContainer interface does not have getFont_NoClientCode()
// and it cannot, because it must be package-private. Because of
// this, we must manually cast classes that implement
// MenuContainer.
Object parent = this.parent;
if (parent != null) {
if (parent instanceof Component) {
font = ((Component)parent).getFont_NoClientCode();
} else if (parent instanceof MenuComponent) {
font = ((MenuComponent)parent).getFont_NoClientCode();
}
}
return font;
} // getFont_NoClientCode()
/**
* Sets the font to be used for this menu component to the specified
* font. This font is also used by all subcomponents of this menu
* component, unless those subcomponents specify a different font.
* <p>
* Some platforms may not support setting of all font attributes
* of a menu component; in such cases, calling <code>setFont</code>
* will have no effect on the unsupported font attributes of this
* menu component. Unless subcomponents of this menu component
* specify a different font, this font will be used by those
* subcomponents if supported by the underlying platform.
*
* @param f the font to be set
* @see #getFont
* @see Font#getAttributes
* @see java.awt.font.TextAttribute
*/
public void setFont(Font f) {
font = f;
//Fixed 6312943: NullPointerException in method MenuComponent.setFont(Font)
MenuComponentPeer peer = this.peer;
if (peer != null) {
peer.setFont(f);
}
}
/**
* Removes the menu component's peer. The peer allows us to modify the
* appearance of the menu component without changing the functionality of
* the menu component.
*/
public void removeNotify() {
synchronized (getTreeLock()) {
MenuComponentPeer p = this.peer;
if (p != null) {
Toolkit.getEventQueue().removeSourceEvents(this, true);
this.peer = null;
p.dispose();
}
}
}
/**
* Posts the specified event to the menu.
* This method is part of the Java 1.0 event system
* and it is maintained only for backwards compatibility.
* Its use is discouraged, and it may not be supported
* in the future.
* @param evt the event which is to take place
* @deprecated As of JDK version 1.1, replaced by {@link
* #dispatchEvent(AWTEvent) dispatchEvent}.
*/
@Deprecated
public boolean postEvent(Event evt) {
MenuContainer parent = this.parent;
if (parent != null) {
parent.postEvent(evt);
}
return false;
}
/**
* Delivers an event to this component or one of its sub components.
* @param e the event
*/
public final void dispatchEvent(AWTEvent e) {
dispatchEventImpl(e);
}
void dispatchEventImpl(AWTEvent e) {
EventQueue.setCurrentEventAndMostRecentTime(e);
Toolkit.getDefaultToolkit().notifyAWTEventListeners(e);
if (newEventsOnly ||
(parent != null && parent instanceof MenuComponent &&
((MenuComponent)parent).newEventsOnly)) {
if (eventEnabled(e)) {
processEvent(e);
} else if (e instanceof ActionEvent && parent != null) {
e.setSource(parent);
((MenuComponent)parent).dispatchEvent(e);
}
} else { // backward compatibility
Event olde = e.convertToOld();
if (olde != null) {
postEvent(olde);
}
}
}
// REMIND: remove when filtering is done at lower level
boolean eventEnabled(AWTEvent e) {
return false;
}
/**
* Processes events occurring on this menu component.
* <p>Note that if the event parameter is <code>null</code>
* the behavior is unspecified and may result in an
* exception.
*
* @param e the event
* @since JDK1.1
*/
protected void processEvent(AWTEvent e) {
}
/**
* Returns a string representing the state of this
* <code>MenuComponent</code>. This method is intended to be used
* only for debugging purposes, and the content and format of the
* returned string may vary between implementations. The returned
* string may be empty but may not be <code>null</code>.
*
* @return the parameter string of this menu component
*/
protected String paramString() {
String thisName = getName();
return (thisName != null? thisName : "");
}
/**
* Returns a representation of this menu component as a string.
* @return a string representation of this menu component
*/
public String toString() {
return getClass().getName() + "[" + paramString() + "]";
}
/**
* Gets this component's locking object (the object that owns the thread
* synchronization monitor) for AWT component-tree and layout
* operations.
* @return this component's locking object
*/
protected final Object getTreeLock() {
return Component.LOCK;
}
/**
* Reads the menu component from an object input stream.
*
* @param s the <code>ObjectInputStream</code> to read
* @exception HeadlessException if
* <code>GraphicsEnvironment.isHeadless</code> returns
* <code>true</code>
* @serial
* @see java.awt.GraphicsEnvironment#isHeadless
*/
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException, HeadlessException
{
GraphicsEnvironment.checkHeadless();
acc = AccessController.getContext();
s.defaultReadObject();
appContext = AppContext.getAppContext();
}
/**
* Initialize JNI field and method IDs.
*/
private static native void initIDs();
/*
* --- Accessibility Support ---
*
* MenuComponent will contain all of the methods in interface Accessible,
* though it won't actually implement the interface - that will be up
* to the individual objects which extend MenuComponent.
*/
AccessibleContext accessibleContext = null;
/**
* Gets the <code>AccessibleContext</code> associated with
* this <code>MenuComponent</code>.
*
* The method implemented by this base class returns <code>null</code>.
* Classes that extend <code>MenuComponent</code>
* should implement this method to return the
* <code>AccessibleContext</code> associated with the subclass.
*
* @return the <code>AccessibleContext</code> of this
* <code>MenuComponent</code>
* @since 1.3
*/
public AccessibleContext getAccessibleContext() {
return accessibleContext;
}
/**
* Inner class of <code>MenuComponent</code> used to provide
* default support for accessibility. This class is not meant
* to be used directly by application developers, but is instead
* meant only to be subclassed by menu component developers.
* <p>
* The class used to obtain the accessible role for this object.
* @since 1.3
*/
protected abstract class AccessibleAWTMenuComponent
extends AccessibleContext
implements java.io.Serializable, AccessibleComponent,
AccessibleSelection
{
/*
* JDK 1.3 serialVersionUID
*/
private static final long serialVersionUID = -4269533416223798698L;
/**
* Although the class is abstract, this should be called by
* all sub-classes.
*/
protected AccessibleAWTMenuComponent() {
}
// AccessibleContext methods
//
/**
* Gets the <code>AccessibleSelection</code> associated with this
* object which allows its <code>Accessible</code> children to be selected.
*
* @return <code>AccessibleSelection</code> if supported by object;
* else return <code>null</code>
* @see AccessibleSelection
*/
public AccessibleSelection getAccessibleSelection() {
return this;
}
/**
* Gets the accessible name of this object. This should almost never
* return <code>java.awt.MenuComponent.getName</code>, as that
* generally isn't a localized name, and doesn't have meaning for the
* user. If the object is fundamentally a text object (e.g. a menu item), the
* accessible name should be the text of the object (e.g. "save").
* If the object has a tooltip, the tooltip text may also be an
* appropriate String to return.
*
* @return the localized name of the object -- can be <code>null</code>
* if this object does not have a name
* @see AccessibleContext#setAccessibleName
*/
public String getAccessibleName() {
return accessibleName;
}
/**
* Gets the accessible description of this object. This should be
* a concise, localized description of what this object is - what
* is its meaning to the user. If the object has a tooltip, the
* tooltip text may be an appropriate string to return, assuming
* it contains a concise description of the object (instead of just
* the name of the object - e.g. a "Save" icon on a toolbar that
* had "save" as the tooltip text shouldn't return the tooltip
* text as the description, but something like "Saves the current
* text document" instead).
*
* @return the localized description of the object -- can be
* <code>null</code> if this object does not have a description
* @see AccessibleContext#setAccessibleDescription
*/
public String getAccessibleDescription() {
return accessibleDescription;
}
/**
* Gets the role of this object.
*
* @return an instance of <code>AccessibleRole</code>
* describing the role of the object
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.AWT_COMPONENT; // Non-specific -- overridden in subclasses
}
/**
* Gets the state of this object.
*
* @return an instance of <code>AccessibleStateSet</code>
* containing the current state set of the object
* @see AccessibleState
*/
public AccessibleStateSet getAccessibleStateSet() {
return MenuComponent.this.getAccessibleStateSet();
}
/**
* Gets the <code>Accessible</code> parent of this object.
* If the parent of this object implements <code>Accessible</code>,
* this method should simply return <code>getParent</code>.
*
* @return the <code>Accessible</code> parent of this object -- can
* be <code>null</code> if this object does not have an
* <code>Accessible</code> parent
*/
public Accessible getAccessibleParent() {
if (accessibleParent != null) {
return accessibleParent;
} else {
MenuContainer parent = MenuComponent.this.getParent();
if (parent instanceof Accessible) {
return (Accessible) parent;
}
}
return null;
}
/**
* Gets the index of this object in its accessible parent.
*
* @return the index of this object in its parent; -1 if this
* object does not have an accessible parent
* @see #getAccessibleParent
*/
public int getAccessibleIndexInParent() {
return MenuComponent.this.getAccessibleIndexInParent();
}
/**
* Returns the number of accessible children in the object. If all
* of the children of this object implement <code>Accessible</code>,
* then this method should return the number of children of this object.
*
* @return the number of accessible children in the object
*/
public int getAccessibleChildrenCount() {
return 0; // MenuComponents don't have children
}
/**
* Returns the nth <code>Accessible</code> child of the object.
*
* @param i zero-based index of child
* @return the nth Accessible child of the object
*/
public Accessible getAccessibleChild(int i) {
return null; // MenuComponents don't have children
}
/**
* Returns the locale of this object.
*
* @return the locale of this object
*/
public java.util.Locale getLocale() {
MenuContainer parent = MenuComponent.this.getParent();
if (parent instanceof Component)
return ((Component)parent).getLocale();
else
return java.util.Locale.getDefault();
}
/**
* Gets the <code>AccessibleComponent</code> associated with
* this object if one exists. Otherwise return <code>null</code>.
*
* @return the component
*/
public AccessibleComponent getAccessibleComponent() {
return this;
}
// AccessibleComponent methods
//
/**
* Gets the background color of this object.
*
* @return the background color, if supported, of the object;
* otherwise, <code>null</code>
*/
public Color getBackground() {
return null; // Not supported for MenuComponents
}
/**
* Sets the background color of this object.
* (For transparency, see <code>isOpaque</code>.)
*
* @param c the new <code>Color</code> for the background
* @see Component#isOpaque
*/
public void setBackground(Color c) {
// Not supported for MenuComponents
}
/**
* Gets the foreground color of this object.
*
* @return the foreground color, if supported, of the object;
* otherwise, <code>null</code>
*/
public Color getForeground() {
return null; // Not supported for MenuComponents
}
/**
* Sets the foreground color of this object.
*
* @param c the new <code>Color</code> for the foreground
*/
public void setForeground(Color c) {
// Not supported for MenuComponents
}
/**
* Gets the <code>Cursor</code> of this object.
*
* @return the <code>Cursor</code>, if supported, of the object;
* otherwise, <code>null</code>
*/
public Cursor getCursor() {
return null; // Not supported for MenuComponents
}
/**
* Sets the <code>Cursor</code> of this object.
* <p>
* The method may have no visual effect if the Java platform
* implementation and/or the native system do not support
* changing the mouse cursor shape.
* @param cursor the new <code>Cursor</code> for the object
*/
public void setCursor(Cursor cursor) {
// Not supported for MenuComponents
}
/**
* Gets the <code>Font</code> of this object.
*
* @return the <code>Font</code>,if supported, for the object;
* otherwise, <code>null</code>
*/
public Font getFont() {
return MenuComponent.this.getFont();
}
/**
* Sets the <code>Font</code> of this object.
*
* @param f the new <code>Font</code> for the object
*/
public void setFont(Font f) {
MenuComponent.this.setFont(f);
}
/**
* Gets the <code>FontMetrics</code> of this object.
*
* @param f the <code>Font</code>
* @return the FontMetrics, if supported, the object;
* otherwise, <code>null</code>
* @see #getFont
*/
public FontMetrics getFontMetrics(Font f) {
return null; // Not supported for MenuComponents
}
/**
* Determines if the object is enabled.
*
* @return true if object is enabled; otherwise, false
*/
public boolean isEnabled() {
return true; // Not supported for MenuComponents
}
/**
* Sets the enabled state of the object.
*
* @param b if true, enables this object; otherwise, disables it
*/
public void setEnabled(boolean b) {
// Not supported for MenuComponents
}
/**
* Determines if the object is visible. Note: this means that the
* object intends to be visible; however, it may not in fact be
* showing on the screen because one of the objects that this object
* is contained by is not visible. To determine if an object is
* showing on the screen, use <code>isShowing</code>.
*
* @return true if object is visible; otherwise, false
*/
public boolean isVisible() {
return true; // Not supported for MenuComponents
}
/**
* Sets the visible state of the object.
*
* @param b if true, shows this object; otherwise, hides it
*/
public void setVisible(boolean b) {
// Not supported for MenuComponents
}
/**
* Determines if the object is showing. This is determined by checking
* the visibility of the object and ancestors of the object. Note:
* this will return true even if the object is obscured by another
* (for example, it happens to be underneath a menu that was pulled
* down).
*
* @return true if object is showing; otherwise, false
*/
public boolean isShowing() {
return true; // Not supported for MenuComponents
}
/**
* Checks whether the specified point is within this object's bounds,
* where the point's x and y coordinates are defined to be relative to
* the coordinate system of the object.
*
* @param p the <code>Point</code> relative to the coordinate
* system of the object
* @return true if object contains <code>Point</code>; otherwise false
*/
public boolean contains(Point p) {
return false; // Not supported for MenuComponents
}
/**
* Returns the location of the object on the screen.
*
* @return location of object on screen -- can be <code>null</code>
* if this object is not on the screen
*/
public Point getLocationOnScreen() {
return null; // Not supported for MenuComponents
}
/**
* Gets the location of the object relative to the parent in the form
* of a point specifying the object's top-left corner in the screen's
* coordinate space.
*
* @return an instance of <code>Point</code> representing the
* top-left corner of the object's bounds in the coordinate
* space of the screen; <code>null</code> if
* this object or its parent are not on the screen
*/
public Point getLocation() {
return null; // Not supported for MenuComponents
}
/**
* Sets the location of the object relative to the parent.
*/
public void setLocation(Point p) {
// Not supported for MenuComponents
}
/**
* Gets the bounds of this object in the form of a
* <code>Rectangle</code> object.
* The bounds specify this object's width, height, and location
* relative to its parent.
*
* @return a rectangle indicating this component's bounds;
* <code>null</code> if this object is not on the screen
*/
public Rectangle getBounds() {
return null; // Not supported for MenuComponents
}
/**
* Sets the bounds of this object in the form of a
* <code>Rectangle</code> object.
* The bounds specify this object's width, height, and location
* relative to its parent.
*
* @param r a rectangle indicating this component's bounds
*/
public void setBounds(Rectangle r) {
// Not supported for MenuComponents
}
/**
* Returns the size of this object in the form of a
* <code>Dimension</code> object. The height field of
* the <code>Dimension</code> object contains this object's
* height, and the width field of the <code>Dimension</code>
* object contains this object's width.
*
* @return a <code>Dimension</code> object that indicates the
* size of this component; <code>null</code>
* if this object is not on the screen
*/
public Dimension getSize() {
return null; // Not supported for MenuComponents
}
/**
* Resizes this object.
*
* @param d - the <code>Dimension</code> specifying the
* new size of the object
*/
public void setSize(Dimension d) {
// Not supported for MenuComponents
}
/**
* Returns the <code>Accessible</code> child, if one exists,
* contained at the local coordinate <code>Point</code>.
* If there is no <code>Accessible</code> child, <code>null</code>
* is returned.
*
* @param p the point defining the top-left corner of the
* <code>Accessible</code>, given in the coordinate space
* of the object's parent
* @return the <code>Accessible</code>, if it exists,
* at the specified location; else <code>null</code>
*/
public Accessible getAccessibleAt(Point p) {
return null; // MenuComponents don't have children
}
/**
* Returns whether this object can accept focus or not.
*
* @return true if object can accept focus; otherwise false
*/
public boolean isFocusTraversable() {
return true; // Not supported for MenuComponents
}
/**
* Requests focus for this object.
*/
public void requestFocus() {
// Not supported for MenuComponents
}
/**
* Adds the specified focus listener to receive focus events from this
* component.
*
* @param l the focus listener
*/
public void addFocusListener(java.awt.event.FocusListener l) {
// Not supported for MenuComponents
}
/**
* Removes the specified focus listener so it no longer receives focus
* events from this component.
*
* @param l the focus listener
*/
public void removeFocusListener(java.awt.event.FocusListener l) {
// Not supported for MenuComponents
}
// AccessibleSelection methods
//
/**
* Returns the number of <code>Accessible</code> children currently selected.
* If no children are selected, the return value will be 0.
*
* @return the number of items currently selected
*/
public int getAccessibleSelectionCount() {
return 0; // To be fully implemented in a future release
}
/**
* Returns an <code>Accessible</code> representing the specified
* selected child in the object. If there isn't a selection, or there are
* fewer children selected than the integer passed in, the return
* value will be <code>null</code>.
* <p>Note that the index represents the i-th selected child, which
* is different from the i-th child.
*
* @param i the zero-based index of selected children
* @return the i-th selected child
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