DirObjectFactory.java

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package javax.naming.spi;

import java.util.Hashtable;
import javax.naming.*;
import javax.naming.directory.Attributes;

/**
  * This interface represents a factory for creating an object given
  * an object and attributes about the object.
  *<p>
  * The JNDI framework allows for object implementations to
  * be loaded in dynamically via <em>object factories</em>. See
  * {@code ObjectFactory} for details.
  * <p>
  * A {@code DirObjectFactory} extends {@code ObjectFactory} by allowing
  * an {@code Attributes} instance
  * to be supplied to the {@code getObjectInstance()} method.
  * {@code DirObjectFactory} implementations are intended to be used by {@code DirContext}
  * service providers. The service provider, in addition reading an
  * object from the directory, might already have attributes that
  * are useful for the object factory to check to see whether the
  * factory is supposed to process the object. For instance, an LDAP-style
  * service provider might have read the "objectclass" of the object.
  * A CORBA object factory might be interested only in LDAP entries
  * with "objectclass=corbaObject". By using the attributes supplied by
  * the LDAP service provider, the CORBA object factory can quickly
  * eliminate objects that it need not worry about, and non-CORBA object
  * factories can quickly eliminate CORBA-related LDAP entries.
  *
  * @author Rosanna Lee
  * @author Scott Seligman
  *
  * @see NamingManager#getObjectInstance
  * @see DirectoryManager#getObjectInstance
  * @see ObjectFactory
  * @since 1.3
  */

public interface DirObjectFactory extends ObjectFactory {
/**
 * Creates an object using the location or reference information, and attributes
 * specified.
 * <p>
 * Special requirements of this object are supplied
 * using <code>environment</code>.
 * An example of such an environment property is user identity
 * information.
 *<p>
 * {@code DirectoryManager.getObjectInstance()}
 * successively loads in object factories. If it encounters a {@code DirObjectFactory},
 * it will invoke {@code DirObjectFactory.getObjectInstance()};
 * otherwise, it invokes
 * {@code ObjectFactory.getObjectInstance()}. It does this until a factory
 * produces a non-null answer.
 * <p> When an exception
 * is thrown by an object factory, the exception is passed on to the caller
 * of {@code DirectoryManager.getObjectInstance()}. The search for other factories
 * that may produce a non-null answer is halted.
 * An object factory should only throw an exception if it is sure that
 * it is the only intended factory and that no other object factories
 * should be tried.
 * If this factory cannot create an object using the arguments supplied,
 * it should return null.
  *<p>Since {@code DirObjectFactory} extends {@code ObjectFactory}, it
  * effectively
  * has two {@code getObjectInstance()} methods, where one differs from the other by
  * the attributes argument. Given a factory that implements {@code DirObjectFactory},
  * {@code DirectoryManager.getObjectInstance()} will only
  * use the method that accepts the attributes argument, while
  * {@code NamingManager.getObjectInstance()} will only use the one that does not accept
  * the attributes argument.
 *<p>
 * See {@code ObjectFactory} for a description URL context factories and other
 * properties of object factories that apply equally to {@code DirObjectFactory}.
 *<p>
 * The {@code name}, {@code attrs}, and {@code environment} parameters
 * are owned by the caller.
 * The implementation will not modify these objects or keep references
 * to them, although it may keep references to clones or copies.
 *
 * @param obj The possibly null object containing location or reference
 *              information that can be used in creating an object.
 * @param name The name of this object relative to <code>nameCtx</code>,
 *              or null if no name is specified.
 * @param nameCtx The context relative to which the <code>name</code>
 *              parameter is specified, or null if <code>name</code> is
 *              relative to the default initial context.
 * @param environment The possibly null environment that is used in
 *              creating the object.
 * @param attrs The possibly null attributes containing some of {@code obj}'s
 * attributes. {@code attrs} might not necessarily have all of {@code obj}'s
 * attributes. If the object factory requires more attributes, it needs
 * to get it, either using {@code obj}, or {@code name} and {@code nameCtx}.
 *      The factory must not modify attrs.
 * @return The object created; null if an object cannot be created.
 * @throws Exception If this object factory encountered an exception
 * while attempting to create an object, and no other object factories are
 * to be tried.
 *
 * @see DirectoryManager#getObjectInstance
 * @see NamingManager#getURLContext
 */
    public Object getObjectInstance(Object obj, Name name, Context nameCtx,
                                    Hashtable<?,?> environment,
                                    Attributes attrs)
        throws Exception;
}