aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 1999, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package javax.activation;
aoqi@0: 
aoqi@0: import java.io.*;
aoqi@0: import java.beans.Beans;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * The CommandInfo class is used by CommandMap implementations to
aoqi@0:  * describe the results of command requests. It provides the requestor
aoqi@0:  * with both the verb requested, as well as an instance of the
aoqi@0:  * bean. There is also a method that will return the name of the
aoqi@0:  * class that implements the command but <i>it is not guaranteed to
aoqi@0:  * return a valid value</i>. The reason for this is to allow CommandMap
aoqi@0:  * implmentations that subclass CommandInfo to provide special
aoqi@0:  * behavior. For example a CommandMap could dynamically generate
aoqi@0:  * JavaBeans. In this case, it might not be possible to create an
aoqi@0:  * object with all the correct state information solely from the class
aoqi@0:  * name.
aoqi@0:  *
aoqi@0:  * @since 1.6
aoqi@0:  */
aoqi@0: 
aoqi@0: public class CommandInfo {
aoqi@0:     private String verb;
aoqi@0:     private String className;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * The Constructor for CommandInfo.
aoqi@0:      * @param verb The command verb this CommandInfo decribes.
aoqi@0:      * @param className The command's fully qualified class name.
aoqi@0:      */
aoqi@0:     public CommandInfo(String verb, String className) {
aoqi@0:         this.verb = verb;
aoqi@0:         this.className = className;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Return the command verb.
aoqi@0:      *
aoqi@0:      * @return the command verb.
aoqi@0:      */
aoqi@0:     public String getCommandName() {
aoqi@0:         return verb;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Return the command's class name. <i>This method MAY return null in
aoqi@0:      * cases where a CommandMap subclassed CommandInfo for its
aoqi@0:      * own purposes.</i> In other words, it might not be possible to
aoqi@0:      * create the correct state in the command by merely knowing
aoqi@0:      * its class name. <b>DO NOT DEPEND ON THIS METHOD RETURNING
aoqi@0:      * A VALID VALUE!</b>
aoqi@0:      *
aoqi@0:      * @return The class name of the command, or <i>null</i>
aoqi@0:      */
aoqi@0:     public String getCommandClass() {
aoqi@0:         return className;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Return the instantiated JavaBean component.
aoqi@0:      * <p>
aoqi@0:      * Begin by instantiating the component with
aoqi@0:      * <code>Beans.instantiate()</code>.
aoqi@0:      * <p>
aoqi@0:      * If the bean implements the <code>javax.activation.CommandObject</code>
aoqi@0:      * interface, call its <code>setCommandContext</code> method.
aoqi@0:      * <p>
aoqi@0:      * If the DataHandler parameter is null, then the bean is
aoqi@0:      * instantiated with no data. NOTE: this may be useful
aoqi@0:      * if for some reason the DataHandler that is passed in
aoqi@0:      * throws IOExceptions when this method attempts to
aoqi@0:      * access its InputStream. It will allow the caller to
aoqi@0:      * retrieve a reference to the bean if it can be
aoqi@0:      * instantiated.
aoqi@0:      * <p>
aoqi@0:      * If the bean does NOT implement the CommandObject interface,
aoqi@0:      * this method will check if it implements the
aoqi@0:      * java.io.Externalizable interface. If it does, the bean's
aoqi@0:      * readExternal method will be called if an InputStream
aoqi@0:      * can be acquired from the DataHandler.<p>
aoqi@0:      *
aoqi@0:      * @param dh        The DataHandler that describes the data to be
aoqi@0:      *                  passed to the command.
aoqi@0:      * @param loader    The ClassLoader to be used to instantiate the bean.
aoqi@0:      * @return The bean
aoqi@0:      * @see java.beans.Beans#instantiate
aoqi@0:      * @see javax.activation.CommandObject
aoqi@0:      */
aoqi@0:     public Object getCommandObject(DataHandler dh, ClassLoader loader)
aoqi@0:                         throws IOException, ClassNotFoundException {
aoqi@0:         Object new_bean = null;
aoqi@0: 
aoqi@0:         // try to instantiate the bean
aoqi@0:         new_bean = java.beans.Beans.instantiate(loader, className);
aoqi@0: 
aoqi@0:         // if we got one and it is a CommandObject
aoqi@0:         if (new_bean != null) {
aoqi@0:             if (new_bean instanceof CommandObject) {
aoqi@0:                 ((CommandObject)new_bean).setCommandContext(verb, dh);
aoqi@0:             } else if (new_bean instanceof Externalizable) {
aoqi@0:                 if (dh != null) {
aoqi@0:                     InputStream is = dh.getInputStream();
aoqi@0:                     if (is != null) {
aoqi@0:                         ((Externalizable)new_bean).readExternal(
aoqi@0:                                                new ObjectInputStream(is));
aoqi@0:                     }
aoqi@0:                 }
aoqi@0:             }
aoqi@0:         }
aoqi@0: 
aoqi@0:         return new_bean;
aoqi@0:     }
aoqi@0: }