/// <summary>
/// Instantiate a bean.
/// <para>
/// 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".
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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.)
/// </para>
/// <para>
/// 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.
/// </para>
/// <para>
/// 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).
///
/// </para>
/// </summary>
/// <returns> a JavaBean </returns>
/// <param name="cls"> the class-loader from which we should create
/// the bean. If this is null, then the system
/// class-loader is used. </param>
/// <param name="beanName"> the name of the bean within the class-loader.
/// For example "sun.beanbox.foobah" </param>
/// <param name="beanContext"> The BeanContext in which to nest the new bean </param>
/// <param name="initializer"> The AppletInitializer for the new bean
/// </param>
/// <exception cref="ClassNotFoundException"> if the class of a serialized
/// object could not be found. </exception>
/// <exception cref="IOException"> if an I/O error occurs. </exception>
//JAVA TO C# CONVERTER WARNING: Method 'throws' clauses are not available in .NET:
//ORIGINAL LINE: public static Object instantiate(ClassLoader cls, String beanName, java.beans.beancontext.BeanContext beanContext, AppletInitializer initializer) throws java.io.IOException, ClassNotFoundException
public static Object Instantiate(ClassLoader cls, String beanName, BeanContext beanContext, AppletInitializer initializer)
{
InputStream ins;
ObjectInputStream oins = null;
Object result = null;
bool 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.SystemClassLoader;
}
catch (SecurityException)
{
// We're not allowed to access the system class loader.
// Drop through.
}
}
// Try to find a serialized object with this name
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String serName = beanName.replace('.','/').concat(".ser");
String serName = beanName.Replace('.', '/') + ".ser";
if (cls == null)
{
ins = ClassLoader.GetSystemResourceAsStream(serName);
}
else
{
ins = cls.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;
}
if (!Modifier.isPublic(cl.Modifiers))
{
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 is Applet)
{
Applet applet = (Applet)result;
bool 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".
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final String resourceName;
String resourceName;
if (serialized)
{
// Serialized bean
resourceName = beanName.Replace('.', '/') + ".ser";
}
else
{
// Regular class
resourceName = beanName.Replace('.', '/') + ".class";
}
URL objectUrl = null;
URL codeBase = null;
URL docBase = null;
// Now get the URL correponding 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 = 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.Stub = 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_Renamed = true;
}
else
{
initializer.Activate(applet);
}
}
else if (beanContext != null)
{
UnsafeBeanContextAdd(beanContext, result);
}
}
return(result);
}