java-jdk源码学习

/* * Copyright (c) 1995, 2015, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * * * * * * * * * * * * * * * * * * * * */ package java.awt; import java.io.PrintStream; import java.io.PrintWriter; import java.util.Objects; import java.util.Vector; import java.util.Locale; import java.util.EventListener; import java.util.HashSet; import java.util.Map; import java.util.Set; import java.util.Collections; import java.awt.peer.ComponentPeer; import java.awt.peer.ContainerPeer; import java.awt.peer.LightweightPeer; import java.awt.image.BufferStrategy; import java.awt.image.ImageObserver; import java.awt.image.ImageProducer; import java.awt.image.ColorModel; import java.awt.image.VolatileImage; import java.awt.event.*; import java.io.Serializable; import java.io.ObjectOutputStream; import java.io.ObjectInputStream; import java.io.IOException; import java.beans.PropertyChangeListener; import java.beans.PropertyChangeSupport; import java.beans.Transient; import java.awt.im.InputContext; import java.awt.im.InputMethodRequests; import java.awt.dnd.DropTarget; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.security.AccessController; import java.security.PrivilegedAction; import java.security.AccessControlContext; import javax.accessibility.*; import java.applet.Applet; import sun.security.action.GetPropertyAction; import sun.awt.AppContext; import sun.awt.AWTAccessor; import sun.awt.ConstrainableGraphics; import sun.awt.SubRegionShowable; import sun.awt.SunToolkit; import sun.awt.WindowClosingListener; import sun.awt.CausedFocusEvent; import sun.awt.EmbeddedFrame; import sun.awt.dnd.SunDropTargetEvent; import sun.awt.im.CompositionArea; import sun.font.FontManager; import sun.font.FontManagerFactory; import sun.font.SunFontManager; import sun.java2d.SunGraphics2D; import sun.java2d.pipe.Region; import sun.awt.image.VSyncedBSManager; import sun.java2d.pipe.hw.ExtendedBufferCapabilities; import static sun.java2d.pipe.hw.ExtendedBufferCapabilities.VSyncType.*; import sun.awt.RequestFocusController; import sun.java2d.SunGraphicsEnvironment; import sun.util.logging.PlatformLogger; /** * A <em>component</em> is an object having a graphical representation * that can be displayed on the screen and that can interact with the * user. Examples of components are the buttons, checkboxes, and scrollbars * of a typical graphical user interface. <p> * The <code>Component</code> class is the abstract superclass of * the nonmenu-related Abstract Window Toolkit components. Class * <code>Component</code> can also be extended directly to create a * lightweight component. A lightweight component is a component that is * not associated with a native window. On the contrary, a heavyweight * component is associated with a native window. The {@link #isLightweight()} * method may be used to distinguish between the two kinds of the components. * <p> * Lightweight and heavyweight components may be mixed in a single component * hierarchy. However, for correct operating of such a mixed hierarchy of * components, the whole hierarchy must be valid. When the hierarchy gets * invalidated, like after changing the bounds of components, or * adding/removing components to/from containers, the whole hierarchy must be * validated afterwards by means of the {@link Container#validate()} method * invoked on the top-most invalid container of the hierarchy. * * <h3>Serialization</h3> * It is important to note that only AWT listeners which conform * to the <code>Serializable</code> protocol will be saved when * the object is stored. If an AWT object has listeners that * aren't marked serializable, they will be dropped at * <code>writeObject</code> time. Developers will need, as always, * to consider the implications of making an object serializable. * One situation to watch out for is this: * <pre> * import java.awt.*; * import java.awt.event.*; * import java.io.Serializable; * * class MyApp implements ActionListener, Serializable * { * BigObjectThatShouldNotBeSerializedWithAButton bigOne; * Button aButton = new Button(); * * MyApp() * { * // Oops, now aButton has a listener with a reference * // to bigOne! * aButton.addActionListener(this); * } * * public void actionPerformed(ActionEvent e) * { * System.out.println("Hello There"); * } * } * </pre> * In this example, serializing <code>aButton</code> by itself * will cause <code>MyApp</code> and everything it refers to * to be serialized as well. The problem is that the listener * is serializable by coincidence, not by design. To separate * the decisions about <code>MyApp</code> and the * <code>ActionListener</code> being serializable one can use a * nested class, as in the following example: * <pre> * import java.awt.*; * import java.awt.event.*; * import java.io.Serializable; * * class MyApp implements java.io.Serializable * { * BigObjectThatShouldNotBeSerializedWithAButton bigOne; * Button aButton = new Button(); * * static class MyActionListener implements ActionListener * { * public void actionPerformed(ActionEvent e) * { * System.out.println("Hello There"); * } * } * * MyApp() * { * aButton.addActionListener(new MyActionListener()); * } * } * </pre> * <p> * <b>Note</b>: For more information on the paint mechanisms utilitized * by AWT and Swing, including information on how to write the most * efficient painting code, see * <a href="http://www.oracle.com/technetwork/java/painting-140037.html">Painting in AWT and Swing</a>. * <p> * For details on the focus subsystem, see * <a href="https://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html"> * How to Use the Focus Subsystem</a>, * a section in <em>The Java Tutorial</em>, and the * <a href="../../java/awt/doc-files/FocusSpec.html">Focus Specification</a> * for more information. * * @author Arthur van Hoff * @author Sami Shaio */ public abstract class Component implements ImageObserver, MenuContainer, Serializable { private static final PlatformLogger log = PlatformLogger.getLogger("java.awt.Component"); private static final PlatformLogger eventLog = PlatformLogger.getLogger("java.awt.event.Component"); private static final PlatformLogger focusLog = PlatformLogger.getLogger("java.awt.focus.Component"); private static final PlatformLogger mixingLog = PlatformLogger.getLogger("java.awt.mixing.Component"); /** * The peer of the component. The peer implements the component's * behavior. The peer is set when the <code>Component</code> is * added to a container that also is a peer. * @see #addNotify * @see #removeNotify */ transient ComponentPeer peer; /** * The parent of the object. It may be <code>null</code> * for top-level components. * @see #getParent */ transient Container parent; /** * The <code>AppContext</code> of the component. Applets/Plugin may * change the AppContext. */ transient AppContext appContext; /** * The x position of the component in the parent's coordinate system. * * @serial * @see #getLocation */ int x; /** * The y position of the component in the parent's coordinate system. * * @serial * @see #getLocation */ int y; /** * The width of the component. * * @serial * @see #getSize */ int width; /** * The height of the component. * * @serial * @see #getSize */ int height; /** * The