Quelle Beans.java Sprache: JAVA

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package java.beans;

import com.sun.beans.finder.ClassFinder;

import java.applet.Applet;
import java.applet.AppletContext;
import java.applet.AppletStub;
import java.applet.AudioClip;

import java.awt.Image;

import java.beans.beancontext.BeanContext;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.StreamCorruptedException;

import java.lang.reflect.Modifier;

import java.net.MalformedURLException;
import java.net.URL;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Vector;

/**
* This class provides some general purpose beans control methods.
*
* @since 1.1
*/

public class Beans {

 /**
 * Constructs a {@code Beans}.
 */
 public Beans() {}

 /**
 * 
 * Instantiate a JavaBean.
 * 
 * @return a JavaBean
 * @param cls the class-loader from which we should create
 * the bean. If this is null, then the system
 * class-loader is used.
 * @param beanName the name of the bean within the class-loader.
 * For example "sun.beanbox.foobah"
 *
 * @throws ClassNotFoundException if the class of a serialized
 * object could not be found.
 * @throws IOException if an I/O error occurs.
 */

 public static Object instantiate(ClassLoader cls, String beanName) throws IOException, ClassNotFoundException {
 return Beans.instantiate(cls, beanName, null, null);
 }

 /**
 * 
 * Instantiate a JavaBean.
 * 
 * @return a JavaBean
 *
 * @param cls the class-loader from which we should create
 * the bean. If this is null, then the system
 * class-loader is used.
 * @param beanName the name of the bean within the class-loader.
 * For example "sun.beanbox.foobah"
 * @param beanContext The BeanContext in which to nest the new bean
 *
 * @throws ClassNotFoundException if the class of a serialized
 * object could not be found.
 * @throws IOException if an I/O error occurs.
 * @since 1.2
 */
 @SuppressWarnings("deprecation")
 public static Object instantiate(ClassLoader cls, String beanName,
 BeanContext beanContext)
 throws IOException, ClassNotFoundException {
 return Beans.instantiate(cls, beanName, beanContext, null);
 }

 /**
 * Instantiate a bean.
 * 
 * The bean is created based on a name relative to a class-loader.
 * This name should be a dot-separated name such as "a.b.c".
 * 
 * In Beans 1.0 the given name can indicate either a serialized object
 * or a class. Other mechanisms may be added in the future. In
 * beans 1.0 we first try to treat the beanName as a serialized object
 * name then as a class name.
 * 
 * When using the beanName as a serialized object name we convert the
 * given beanName to a resource pathname and add a trailing ".ser" suffix.
 * We then try to load a serialized object from that resource.
 * 
 * For example, given a beanName of "x.y", Beans.instantiate would first
 * try to read a serialized object from the resource "x/y.ser" and if
 * that failed it would try to load the class "x.y" and create an
 * instance of that class.
 * 
 * If the bean is a subtype of java.applet.Applet, then it is given
 * some special initialization. First, it is supplied with a default
 * AppletStub and AppletContext. Second, if it was instantiated from
 * a classname the applet's "init" method is called. (If the bean was
 * deserialized this step is skipped.)
 * 
 * Note that for beans which are applets, it is the caller's responsibility
 * to call "start" on the applet. For correct behaviour, this should be done
 * after the applet has been added into a visible AWT container.
 * 
 * Note that applets created via beans.instantiate run in a slightly
 * different environment than applets running inside browsers. In
 * particular, bean applets have no access to "parameters", so they may
 * wish to provide property get/set methods to set parameter values. We
 * advise bean-applet developers to test their bean-applets against both
 * the JDK appletviewer (for a reference browser environment) and the
 * BDK BeanBox (for a reference bean container).
 *
 * @return a JavaBean
 * @param cls the class-loader from which we should create
 * the bean. If this is null, then the system
 * class-loader is used.
 * @param beanName the name of the bean within the class-loader.
 * For example "sun.beanbox.foobah"
 * @param beanContext The BeanContext in which to nest the new bean
 * @param initializer The AppletInitializer for the new bean
 *
 * @throws ClassNotFoundException if the class of a serialized
 * object could not be found.
 * @throws IOException if an I/O error occurs.
 * @since 1.2
 *
 * @deprecated It is recommended to use
 * {@link #instantiate(ClassLoader, String, BeanContext)},
 * because the Applet API is deprecated. See the
 * <a href="../../java/applet/package-summary.html"> java.applet package
 * documentation</a> for further information.
 */
 @Deprecated(since = "9", forRemoval = true)
 @SuppressWarnings("removal")
 public static Object instantiate(ClassLoader cls, String beanName,
 BeanContext beanContext,
 AppletInitializer initializer)
 throws IOException, ClassNotFoundException {

 InputStream ins;
 ObjectInputStream oins = null;
 Object result = null;
 boolean serialized = false;
 IOException serex = null;

 // If the given classloader is null, we check if an
 // system classloader is available and (if so)
 // use that instead.
 // Note that calls on the system class loader will
 // look in the bootstrap class loader first.
 if (cls == null) {
 try {
 cls = ClassLoader.getSystemClassLoader();
 } catch (SecurityException ex) {
 // We're not allowed to access the system class loader.
 // Drop through.
 }
 }

 // Try to find a serialized object with this name
 final String serName = beanName.replace('.','/').concat(".ser");
 if (cls == null)
 ins = ClassLoader.getSystemResourceAsStream(serName);
 else
 ins = cls.getResourceAsStream(serName);
 if (ins != null) {
 try (ins) {
 if (cls == null) {
 oins = new ObjectInputStream(ins);
 } else {
 oins = new ObjectInputStreamWithLoader(ins, cls);
 }
 result = oins.readObject();
 serialized = true;
 oins.close();
 } catch (IOException ex) {
 // Drop through and try opening the class. But remember
 // the exception in case we can't find the class either.
 serex = ex;
 }
 }

 if (result == null) {
 // No serialized object, try just instantiating the class
 Class<?> cl;

 try {
 cl = ClassFinder.findClass(beanName, cls);
 } catch (ClassNotFoundException ex) {
 // There is no appropriate class. If we earlier tried to
 // deserialize an object and got an IO exception, throw that,
 // otherwise rethrow the ClassNotFoundException.
 if (serex != null) {
 throw serex;
 }
 throw ex;
 }

 if (!Modifier.isPublic(cl.getModifiers())) {
 throw new ClassNotFoundException("" + cl + " : no public access");
 }

 /*
 * Try to instantiate the class.
 */

 try {
 result = cl.newInstance();
 } catch (Exception ex) {
 // We have to remap the exception to one in our signature.
 // But we pass extra information in the detail message.
 throw new ClassNotFoundException("" + cl + " : " + ex, ex);
 }
 }

 if (result != null) {

 // Ok, if the result is an applet initialize it.

 AppletStub stub = null;

 if (result instanceof Applet) {
 Applet applet = (Applet) result;
 boolean needDummies = initializer == null;

 if (needDummies) {

 // Figure our the codebase and docbase URLs. We do this
 // by locating the URL for a known resource, and then
 // massaging the URL.

 // First find the "resource name" corresponding to the bean
 // itself. So a serialzied bean "a.b.c" would imply a
 // resource name of "a/b/c.ser" and a classname of "x.y"
 // would imply a resource name of "x/y.class".

 final String resourceName;

 if (serialized) {
 // Serialized bean
 resourceName = beanName.replace('.','/').concat(".ser");
 } else {
 // Regular class
 resourceName = beanName.replace('.','/').concat(".class");
 }

 URL objectUrl = null;
 URL codeBase = null;
 URL docBase = null;

 // Now get the URL corresponding to the resource name.
 if (cls == null) {
 objectUrl = ClassLoader.getSystemResource(resourceName);
 } else
 objectUrl = cls.getResource(resourceName);

 // If we found a URL, we try to locate the docbase by taking
 // of the final path name component, and the code base by taking
 // of the complete resourceName.
 // So if we had a resourceName of "a/b/c.class" and we got an
 // objectURL of "file://bert/classes/a/b/c.class" then we would
 // want to set the codebase to "file://bert/classes/" and the
 // docbase to "file://bert/classes/a/b/"

 if (objectUrl != null) {
 String s = objectUrl.toExternalForm();

 if (s.endsWith(resourceName)) {
 int ix = s.length() - resourceName.length();
 codeBase = newURL(s.substring(0,ix));
 docBase = codeBase;

 ix = s.lastIndexOf('/');

 if (ix >= 0) {
 docBase = newURL(s.substring(0,ix+1));
 }
 }
 }

 // Setup a default context and stub.
 BeansAppletContext context = new BeansAppletContext(applet);

 stub = (AppletStub)new BeansAppletStub(applet, context, codeBase, docBase);
 applet.setStub(stub);
 } else {
 initializer.initialize(applet, beanContext);
 }

 // now, if there is a BeanContext, add the bean, if applicable.

 if (beanContext != null) {
 unsafeBeanContextAdd(beanContext, result);
 }

 // If it was deserialized then it was already init-ed.
 // Otherwise we need to initialize it.

 if (!serialized) {
 // We need to set a reasonable initial size, as many
 // applets are unhappy if they are started without
 // having been explicitly sized.
 applet.setSize(100,100);
 applet.init();
 }

 if (needDummies) {
 ((BeansAppletStub)stub).active = true;
 } else initializer.activate(applet);

 } else if (beanContext != null) unsafeBeanContextAdd(beanContext, result);
 }

 return result;
 }

 @SuppressWarnings("unchecked")
 private static void unsafeBeanContextAdd(BeanContext beanContext, Object res) {
 beanContext.add(res);
 }

 @SuppressWarnings("deprecation")
 private static URL newURL(String spec) throws MalformedURLException {
 return new URL(spec);
 }

 /**
 * From a given bean, obtain an object representing a specified
 * type view of that source object.
 * 
 * The result may be the same object or a different object. If
 * the requested target view isn't available then the given
 * bean is returned.
 * 
 * This method is provided in Beans 1.0 as a hook to allow the
 * addition of more flexible bean behaviour in the future.
 *
 * @return an object representing a specified type view of the
 * source object
 * @param bean Object from which we want to obtain a view.
 * @param targetType The type of view we'd like to get.
 *
 */
 public static Object getInstanceOf(Object bean, Class<?> targetType) {
 return bean;
 }

 /**
 * Check if a bean can be viewed as a given target type.
 * The result will be true if the Beans.getInstanceof method
 * can be used on the given bean to obtain an object that
 * represents the specified targetType type view.
 *
 * @param bean Bean from which we want to obtain a view.
 * @param targetType The type of view we'd like to get.
 * @return "true" if the given bean supports the given targetType.
 *
 */
 public static boolean isInstanceOf(Object bean, Class<?> targetType) {
 return Introspector.isSubclass(bean.getClass(), targetType);
 }

 /**
 * Test if we are in design-mode.
 *
 * @return True if we are running in an application construction
 * environment.
 *
 * @see DesignMode
 */
 public static boolean isDesignTime() {
 return ThreadGroupContext.getContext().isDesignTime();
 }

 /**
 * Determines whether beans can assume a GUI is available.
 *
 * @return True if we are running in an environment where beans
 * can assume that an interactive GUI is available, so they
 * can pop up dialog boxes, etc. This will normally return
 * true in a windowing environment, and will normally return
 * false in a server environment or if an application is
 * running as part of a batch job.
 *
 * @see Visibility
 *
 */
 public static boolean isGuiAvailable() {
 return ThreadGroupContext.getContext().isGuiAvailable();
 }

 /**
 * Used to indicate whether of not we are running in an application
 * builder environment.
 *
 * Note that this method is security checked
 * and is not available to (for example) untrusted applets.
 * More specifically, if there is a security manager,
 * its {@code checkPropertiesAccess}
 * method is called. This could result in a SecurityException.
 *
 * @param isDesignTime True if we're in an application builder tool.
 * @throws SecurityException if a security manager exists and its
 * {@code checkPropertiesAccess} method doesn't allow setting
 * of system properties.
 * @see SecurityManager#checkPropertiesAccess
 */

 public static void setDesignTime(boolean isDesignTime)
 throws SecurityException {
 @SuppressWarnings("removal")
 SecurityManager sm = System.getSecurityManager();
 if (sm != null) {
 sm.checkPropertiesAccess();
 }
 ThreadGroupContext.getContext().setDesignTime(isDesignTime);
 }

 /**
 * Used to indicate whether of not we are running in an environment
 * where GUI interaction is available.
 *
 * Note that this method is security checked
 * and is not available to (for example) untrusted applets.
 * More specifically, if there is a security manager,
 * its {@code checkPropertiesAccess}
 * method is called. This could result in a SecurityException.
 *
 * @param isGuiAvailable True if GUI interaction is available.
 * @throws SecurityException if a security manager exists and its
 * {@code checkPropertiesAccess} method doesn't allow setting
 * of system properties.
 * @see SecurityManager#checkPropertiesAccess
 */

 public static void setGuiAvailable(boolean isGuiAvailable)
 throws SecurityException {
 @SuppressWarnings("removal")
 SecurityManager sm = System.getSecurityManager();
 if (sm != null) {
 sm.checkPropertiesAccess();
 }
 ThreadGroupContext.getContext().setGuiAvailable(isGuiAvailable);
 }
}

/**
* This subclass of ObjectInputStream delegates loading of classes to
* an existing ClassLoader.
*/

class ObjectInputStreamWithLoader extends ObjectInputStream
{
 private ClassLoader loader;

 /**
 * Loader must be non-null;
 */

 public ObjectInputStreamWithLoader(InputStream in, ClassLoader loader)
 throws IOException, StreamCorruptedException {

 super(in);
 if (loader == null) {
 throw new IllegalArgumentException("Illegal null argument to ObjectInputStreamWithLoader");
 }
 this.loader = loader;
 }

 /**
 * Use the given ClassLoader rather than using the system class
 */
 @SuppressWarnings("rawtypes")
 protected Class resolveClass(ObjectStreamClass classDesc)
 throws IOException, ClassNotFoundException {

 String cname = classDesc.getName();
 return ClassFinder.resolveClass(cname, this.loader);
 }
}

/**
* Package private support class. This provides a default AppletContext
* for beans which are applets.
*/
@Deprecated(since = "9", forRemoval = true)
@SuppressWarnings("removal")
class BeansAppletContext implements AppletContext {
 Applet target;
 Hashtable<URL,Object> imageCache = new Hashtable<>();

 BeansAppletContext(Applet target) {
 this.target = target;
 }

 public AudioClip getAudioClip(URL url) {
 // We don't currently support audio clips in the Beans.instantiate
 // applet context, unless by some luck there exists a URL content
 // class that can generate an AudioClip from the audio URL.
 try {
 return (AudioClip) url.getContent();
 } catch (Exception ex) {
 return null;
 }
 }

 public synchronized Image getImage(URL url) {
 Object o = imageCache.get(url);
 if (o != null) {
 return (Image)o;
 }
 try {
 o = url.getContent();
 if (o == null) {
 return null;
 }
 if (o instanceof Image) {
 imageCache.put(url, o);
 return (Image) o;
 }
 // Otherwise it must be an ImageProducer.
 Image img = target.createImage((java.awt.image.ImageProducer)o);
 imageCache.put(url, img);
 return img;

 } catch (Exception ex) {
 return null;
 }
 }

 public Applet getApplet(String name) {
 return null;
 }

 public Enumeration<Applet> getApplets() {
 Vector<Applet> applets = new Vector<>();
 applets.addElement(target);
 return applets.elements();
 }

 public void showDocument(URL url) {
 // We do nothing.
 }

 public void showDocument(URL url, String target) {
 // We do nothing.
 }

 public void showStatus(String status) {
 // We do nothing.
 }

 public void setStream(String key, InputStream stream)throws IOException{
 // We do nothing.
 }

 public InputStream getStream(String key){
 // We do nothing.
 return null;
 }

 public Iterator<String> getStreamKeys(){
 // We do nothing.
 return null;
 }
}

/**
* Package private support class. This provides an AppletStub
* for beans which are applets.
*/
@Deprecated(since = "9", forRemoval = true)
@SuppressWarnings("removal")
class BeansAppletStub implements AppletStub {
 transient boolean active;
 transient Applet target;
 transient AppletContext context;
 transient URL codeBase;
 transient URL docBase;

 BeansAppletStub(Applet target,
 AppletContext context, URL codeBase,
 URL docBase) {
 this.target = target;
 this.context = context;
 this.codeBase = codeBase;
 this.docBase = docBase;
 }

 public boolean isActive() {
 return active;
 }

 public URL getDocumentBase() {
 // use the root directory of the applet's class-loader
 return docBase;
 }

 public URL getCodeBase() {
 // use the directory where we found the class or serialized object.
 return codeBase;
 }

 public String getParameter(String name) {
 return null;
 }

 public AppletContext getAppletContext() {
 return context;
 }

 public void appletResize(int width, int height) {
 // we do nothing.
 }
}

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