* Instantiate 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" * * @exception ClassNotFoundException if the class of a serialized * object could not be found. * @exception 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. *
* * @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 * * @exception ClassNotFoundException if the class of a serialized * object could not be found. * @exception IOException if an I/O error occurs. */ 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 responsiblity * 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). * * @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 * * @exception ClassNotFoundException if the class of a serialized * object could not be found. * @exception IOException if an I/O error occurs. */ 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"); final ClassLoader loader = cls; ins = (InputStream)AccessController.doPrivileged (new PrivilegedAction() { public Object run() { if (loader == null) return ClassLoader.getSystemResourceAsStream(serName); else return loader.getResourceAsStream(serName); } }); if (ins != null) { try { if (cls == null) { oins = new ObjectInputStream(ins); } else { oins = new ObjectInputStreamWithLoader(ins, cls); } result = oins.readObject(); serialized = true; oins.close(); } catch (IOException ex) { ins.close(); // Drop through and try opening the class. But remember // the exception in case we can't find the class either. serex = ex; } catch (ClassNotFoundException ex) { ins.close(); throw 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; } /* * 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 correponding to the resource name. final ClassLoader cloader = cls; objectUrl = (URL) AccessController.doPrivileged (new PrivilegedAction() { public Object run() { if (cloader == null) return ClassLoader.getSystemResource (resourceName); else return cloader.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 = new URL(s.substring(0,ix)); docBase = codeBase; ix = s.lastIndexOf('/'); if (ix >= 0) { docBase = new URL(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) { beanContext.add(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) beanContext.add(result); } return result; } /** * 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. * * @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 checkPropertiesAccess
* method is called. This could result in a SecurityException.
*
* @param isDesignTime True if we're in an application builder tool.
* @exception SecurityException if a security manager exists and its
* checkPropertiesAccess method doesn't allow setting
* of system properties.
* @see SecurityManager#checkPropertiesAccess
*/
public static void setDesignTime(boolean isDesignTime)
throws SecurityException {
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 checkPropertiesAccess
* method is called. This could result in a SecurityException.
*
* @param isGuiAvailable True if GUI interaction is available.
* @exception SecurityException if a security manager exists and its
* checkPropertiesAccess method doesn't allow setting
* of system properties.
* @see SecurityManager#checkPropertiesAccess
*/
public static void setGuiAvailable(boolean isGuiAvailable)
throws SecurityException {
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
*/
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.
*/
class BeansAppletContext implements AppletContext {
Applet target;
Hashtable 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 getApplets() {
Vector 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 getStreamKeys(){
// We do nothing.
return null;
}
}
/**
* Package private support class. This provides an AppletStub
* for beans which are applets.
*/
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.
}
}