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