Creates a context for the given URL scheme id.

The resulting context is for resolving URLs of the scheme scheme. The resulting context is not tied to a specific URL. It is able to handle arbitrary URLs with the specified scheme.

The class name of the factory that creates the resulting context has the naming convention scheme-idURLContextFactory (e.g. "ftpURLContextFactory" for the "ftp" scheme-id), in the package specified as follows. The Context.URL_PKG_PREFIXES environment property (which may contain values taken from applet parameters, system properties, or application resource files) contains a colon-separated list of package prefixes. Each package prefix in the property is tried in the order specified to load the factory class. The default package prefix is "com.sun.jndi.url" (if none of the specified packages work, this default is tried). The complete package name is constructed using the package prefix, concatenated with the scheme id.

For example, if the scheme id is "ldap", and the Context.URL_PKG_PREFIXES property contains "com.widget:com.wiz.jndi", the naming manager would attempt to load the following classes until one is successfully instantiated:

com.widget.ldap.ldapURLContextFactory
com.wiz.jndi.ldap.ldapURLContextFactory
com.sun.jndi.url.ldap.ldapURLContextFactory

If none of the package prefixes work, null is returned.

If a factory is instantiated, it is invoked with the following parameters to produce the resulting context.

factory.getObjectInstance(null, environment);

For example, invoking getObjectInstance() as shown above on a LDAP URL context factory would return a context that can resolve LDAP urls (e.g. "ldap://ldap.wiz.com/o=wiz,c=us", "ldap://ldap.umich.edu/o=umich,c=us", ...).

Note that an object factory (an object that implements the ObjectFactory interface) must be public and must have a public constructor that accepts no arguments.

Parameters:

scheme The non-null scheme-id of the URLs supported by the context.

environment The possibly null environment properties to be used in the creation of the object factory and the context.

Returns: A context for resolving URLs with the scheme id scheme; null if the factory for creating the context is not found.

Exceptions:

NamingException If a naming exception occurs while creating the context.

`scheme`		The non-null scheme-id of the URLs supported by the context.
`environment`		The possibly null environment properties to be used in the creation of the object factory and the context.