JDK14/Java14源码在线阅读
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* accompanied this code).
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package java.awt;
import java.awt.event.KeyEvent;
import java.awt.peer.MenuBarPeer;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.Vector;
import javax.accessibility.Accessible;
import javax.accessibility.AccessibleContext;
import javax.accessibility.AccessibleRole;
import sun.awt.AWTAccessor;
/**
* The {@code MenuBar} class encapsulates the platform's
* concept of a menu bar bound to a frame. In order to associate
* the menu bar with a {@code Frame} object, call the
* frame's {@code setMenuBar} method.
* <p>
* <a id="mbexample"></a><!-- target for cross references -->
* This is what a menu bar might look like:
* <p>
* <img src="doc-files/MenuBar-1.gif"
* alt="Diagram of MenuBar containing 2 menus: Examples and Options. Examples
* menu is expanded showing items: Basic, Simple, Check, and More Examples."
* style="margin: 7px 10px;">
* <p>
* A menu bar handles keyboard shortcuts for menu items, passing them
* along to its child menus.
* (Keyboard shortcuts, which are optional, provide the user with
* an alternative to the mouse for invoking a menu item and the
* action that is associated with it.)
* Each menu item can maintain an instance of {@code MenuShortcut}.
* The {@code MenuBar} class defines several methods,
* {@link MenuBar#shortcuts} and
* {@link MenuBar#getShortcutMenuItem}
* that retrieve information about the shortcuts a given
* menu bar is managing.
*
* @author Sami Shaio
* @see java.awt.Frame
* @see java.awt.Frame#setMenuBar(java.awt.MenuBar)
* @see java.awt.Menu
* @see java.awt.MenuItem
* @see java.awt.MenuShortcut
* @since 1.0
*/
public class MenuBar extends MenuComponent implements MenuContainer, Accessible {
static {
/* ensure that the necessary native libraries are loaded */
Toolkit.loadLibraries();
if (!GraphicsEnvironment.isHeadless()) {
initIDs();
}
AWTAccessor.setMenuBarAccessor(
new AWTAccessor.MenuBarAccessor() {
public Menu getHelpMenu(MenuBar menuBar) {
return menuBar.helpMenu;
}
public Vector<Menu> getMenus(MenuBar menuBar) {
return menuBar.menus;
}
});
}
/**
* This field represents a vector of the
* actual menus that will be part of the MenuBar.
*
* @serial
* @see #countMenus()
*/
private final Vector<Menu> menus = new Vector<>();
/**
* This menu is a special menu dedicated to
* help. The one thing to note about this menu
* is that on some platforms it appears at the
* right edge of the menubar.
*
* @serial
* @see #getHelpMenu()
* @see #setHelpMenu(Menu)
*/
private volatile Menu helpMenu;
private static final String base = "menubar";
private static int nameCounter = 0;
/*
* JDK 1.1 serialVersionUID
*/
private static final long serialVersionUID = -4930327919388951260L;
/**
* Creates a new menu bar.
* @exception HeadlessException if GraphicsEnvironment.isHeadless()
* returns true.
* @see java.awt.GraphicsEnvironment#isHeadless
*/
public MenuBar() throws HeadlessException {
}
/**
* Construct a name for this MenuComponent. Called by getName() when
* the name is null.
*/
String constructComponentName() {
synchronized (MenuBar.class) {
return base + nameCounter++;
}
}
/**
* Creates the menu bar's peer. The peer allows us to change the
* appearance of the menu bar without changing any of the menu bar's
* functionality.
*/
public void addNotify() {
synchronized (getTreeLock()) {
if (peer == null)
peer = getComponentFactory().createMenuBar(this);
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
getMenu(i).addNotify();
}
}
}
/**
* Removes the menu bar's peer. The peer allows us to change the
* appearance of the menu bar without changing any of the menu bar's
* functionality.
*/
public void removeNotify() {
synchronized (getTreeLock()) {
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
getMenu(i).removeNotify();
}
super.removeNotify();
}
}
/**
* Gets the help menu on the menu bar.
* @return the help menu on this menu bar.
*/
public Menu getHelpMenu() {
return helpMenu;
}
/**
* Sets the specified menu to be this menu bar's help menu.
* If this menu bar has an existing help menu, the old help menu is
* removed from the menu bar, and replaced with the specified menu.
* @param m the menu to be set as the help menu
*/
public void setHelpMenu(final Menu m) {
synchronized (getTreeLock()) {
if (helpMenu == m) {
return;
}
if (helpMenu != null) {
remove(helpMenu);
}
helpMenu = m;
if (m != null) {
if (m.parent != this) {
add(m);
}
m.isHelpMenu = true;
m.parent = this;
MenuBarPeer peer = (MenuBarPeer)this.peer;
if (peer != null) {
if (m.peer == null) {
m.addNotify();
}
peer.addHelpMenu(m);
}
}
}
}
/**
* Adds the specified menu to the menu bar.
* If the menu has been part of another menu bar,
* removes it from that menu bar.
*
* @param m the menu to be added
* @return the menu added
* @see java.awt.MenuBar#remove(int)
* @see java.awt.MenuBar#remove(java.awt.MenuComponent)
*/
public Menu add(Menu m) {
synchronized (getTreeLock()) {
if (m.parent != null) {
m.parent.remove(m);
}
m.parent = this;
MenuBarPeer peer = (MenuBarPeer)this.peer;
if (peer != null) {
if (m.peer == null) {
m.addNotify();
}
menus.addElement(m);
peer.addMenu(m);
} else {
menus.addElement(m);
}
return m;
}
}
/**
* Removes the menu located at the specified
* index from this menu bar.
* @param index the position of the menu to be removed.
* @see java.awt.MenuBar#add(java.awt.Menu)
*/
public void remove(final int index) {
synchronized (getTreeLock()) {
Menu m = getMenu(index);
menus.removeElementAt(index);
MenuBarPeer peer = (MenuBarPeer)this.peer;
if (peer != null) {
peer.delMenu(index);
m.removeNotify();
}
m.parent = null;
if (helpMenu == m) {
helpMenu = null;
m.isHelpMenu = false;
}
}
}
/**
* Removes the specified menu component from this menu bar.
* @param m the menu component to be removed.
* @see java.awt.MenuBar#add(java.awt.Menu)
*/
public void remove(MenuComponent m) {
synchronized (getTreeLock()) {
int index = menus.indexOf(m);
if (index >= 0) {
remove(index);
}
}
}
/**
* Gets the number of menus on the menu bar.
* @return the number of menus on the menu bar.
* @since 1.1
*/
public int getMenuCount() {
return countMenus();
}
/**
* Gets the number of menus on the menu bar.
*
* @return the number of menus on the menu bar.
* @deprecated As of JDK version 1.1,
* replaced by {@code getMenuCount()}.
*/
@Deprecated
public int countMenus() {
return getMenuCountImpl();
}
/*
* This is called by the native code, so client code can't
* be called on the toolkit thread.
*/
final int getMenuCountImpl() {
return menus.size();
}
/**
* Gets the specified menu.
* @param i the index position of the menu to be returned.
* @return the menu at the specified index of this menu bar.
*/
public Menu getMenu(int i) {
return getMenuImpl(i);
}
/*
* This is called by the native code, so client code can't
* be called on the toolkit thread.
*/
final Menu getMenuImpl(int i) {
return menus.elementAt(i);
}
/**
* Gets an enumeration of all menu shortcuts this menu bar
* is managing.
* @return an enumeration of menu shortcuts that this
* menu bar is managing.
* @see java.awt.MenuShortcut
* @since 1.1
*/
public synchronized Enumeration<MenuShortcut> shortcuts() {
Vector<MenuShortcut> shortcuts = new Vector<>();
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
Enumeration<MenuShortcut> e = getMenu(i).shortcuts();
while (e.hasMoreElements()) {
shortcuts.addElement(e.nextElement());
}
}
return shortcuts.elements();
}
/**
* Gets the instance of {@code MenuItem} associated
* with the specified {@code MenuShortcut} object,
* or {@code null} if none of the menu items being managed
* by this menu bar is associated with the specified menu
* shortcut.
* @param s the specified menu shortcut.
* @return the menu item for the specified shortcut.
* @see java.awt.MenuItem
* @see java.awt.MenuShortcut
* @since 1.1
*/
public MenuItem getShortcutMenuItem(MenuShortcut s) {
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
MenuItem mi = getMenu(i).getShortcutMenuItem(s);
if (mi != null) {
return mi;
}
}
return null; // MenuShortcut wasn't found
}
/*
* Post an ACTION_EVENT to the target of the MenuPeer
* associated with the specified keyboard event (on
* keydown). Returns true if there is an associated
* keyboard event.
*/
boolean handleShortcut(KeyEvent e) {
// Is it a key event?
int id = e.getID();
if (id != KeyEvent.KEY_PRESSED && id != KeyEvent.KEY_RELEASED) {
return false;
}
// Is the accelerator modifier key pressed?
int accelKey = Toolkit.getDefaultToolkit().getMenuShortcutKeyMaskEx();
if ((e.getModifiersEx() & accelKey) == 0) {
return false;
}
// Pass MenuShortcut on to child menus.
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
Menu m = getMenu(i);
if (m.handleShortcut(e)) {
return true;
}
}
return false;
}
/**
* Deletes the specified menu shortcut.
* @param s the menu shortcut to delete.
* @since 1.1
*/
public void deleteShortcut(MenuShortcut s) {
int nmenus = getMenuCount();
for (int i = 0 ; i < nmenus ; i++) {
getMenu(i).deleteShortcut(s);
}
}
/* Serialization support. Restore the (transient) parent
* fields of Menubar menus here.
*/
/**
* The MenuBar's serialized data version.
*
* @serial
*/
private int menuBarSerializedDataVersion = 1;
/**
* Writes default serializable fields to stream.
*
* @param s the {@code ObjectOutputStream} to write
* @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
* @see #readObject(java.io.ObjectInputStream)
*/
private void writeObject(java.io.ObjectOutputStream s)
throws java.io.IOException
{
s.defaultWriteObject();
}
/**
* Reads the {@code ObjectInputStream}.
* Unrecognized keys or values will be ignored.
*
* @param s the {@code ObjectInputStream} to read
* @exception HeadlessException if
* {@code GraphicsEnvironment.isHeadless} returns
* {@code true}
* @see java.awt.GraphicsEnvironment#isHeadless
* @see #writeObject(java.io.ObjectOutputStream)
*/
private void readObject(ObjectInputStream s)
throws ClassNotFoundException, IOException, HeadlessException
{
// HeadlessException will be thrown from MenuComponent's readObject
s.defaultReadObject();
for (int i = 0; i < menus.size(); i++) {
Menu m = menus.elementAt(i);
m.parent = this;
}
}
/**
* Initialize JNI field and method IDs
*/
private static native void initIDs();
/////////////////
// Accessibility support
////////////////
/**
* Gets the AccessibleContext associated with this MenuBar.
* For menu bars, the AccessibleContext takes the form of an
* AccessibleAWTMenuBar.
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