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/*
 * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package javax.activation;

import java.io.*;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 * The CommandInfo class is used by CommandMap implementations to
 * describe the results of command requests. It provides the requestor
 * with both the verb requested, as well as an instance of the
 * bean. There is also a method that will return the name of the
 * class that implements the command but it is not guaranteed to
 * return a valid value. The reason for this is to allow CommandMap
 * implmentations that subclass CommandInfo to provide special
 * behavior. For example a CommandMap could dynamically generate
 * JavaBeans. In this case, it might not be possible to create an
 * object with all the correct state information solely from the class
 * name.
 */

public class CommandInfo {
    private String verb;
    private String className;

    /**
     * The Constructor for CommandInfo.
     * @param verb The command verb this CommandInfo decribes.
     * @param className The command's fully qualified class name.
     */
    public CommandInfo(String verb, String className) {
	this.verb = verb;
	this.className = className;
    }

    /**
     * Return the command verb.
     *
     * @return the command verb.
     */
    public String getCommandName() {
	return verb;
    }

    /**
     * Return the command's class name. This method MAY return null in
     * cases where a CommandMap subclassed CommandInfo for its
     * own purposes. In other words, it might not be possible to
     * create the correct state in the command by merely knowing
     * its class name. DO NOT DEPEND ON THIS METHOD RETURNING
     * A VALID VALUE!
     *
     * @return The class name of the command, or null
     */
    public String getCommandClass() {
	return className;
    }

    /**
     * Return the instantiated JavaBean component.
     * 

* If the current runtime environment supports * {@link java.beans.Beans#instantiate Beans.instantiate}, * use it to instantiate the JavaBeans component. Otherwise, use * {@link java.lang.Class#forName Class.forName}. *

* The component class needs to be public. * On Java SE 9 and newer, if the component class is in a named module, * it needs to be in an exported package. *

* If the bean implements the javax.activation.CommandObject * interface, call its setCommandContext method. *

* If the DataHandler parameter is null, then the bean is * instantiated with no data. NOTE: this may be useful * if for some reason the DataHandler that is passed in * throws IOExceptions when this method attempts to * access its InputStream. It will allow the caller to * retrieve a reference to the bean if it can be * instantiated. *

* If the bean does NOT implement the CommandObject interface, * this method will check if it implements the * java.io.Externalizable interface. If it does, the bean's * readExternal method will be called if an InputStream * can be acquired from the DataHandler.

* * @param dh The DataHandler that describes the data to be * passed to the command. * @param loader The ClassLoader to be used to instantiate the bean. * @return The bean * @exception IOException for failures reading data * @exception ClassNotFoundException if command object class can't * be found * @see java.beans.Beans#instantiate * @see javax.activation.CommandObject */ public Object getCommandObject(DataHandler dh, ClassLoader loader) throws IOException, ClassNotFoundException { Object new_bean = null; // try to instantiate the bean new_bean = Beans.instantiate(loader, className); // if we got one and it is a CommandObject if (new_bean != null) { if (new_bean instanceof CommandObject) { ((CommandObject)new_bean).setCommandContext(verb, dh); } else if (new_bean instanceof Externalizable) { if (dh != null) { InputStream is = dh.getInputStream(); if (is != null) { ((Externalizable)new_bean).readExternal( new ObjectInputStream(is)); } } } } return new_bean; } /** * Helper class to invoke Beans.instantiate reflectively or the equivalent * with core reflection when module java.desktop is not readable. */ private static final class Beans { static final Method instantiateMethod; static { Method m; try { Class c = Class.forName("java.beans.Beans"); m = c.getDeclaredMethod("instantiate", ClassLoader.class, String.class); } catch (ClassNotFoundException e) { m = null; } catch (NoSuchMethodException e) { m = null; } instantiateMethod = m; } /** * Equivalent to invoking java.beans.Beans.instantiate(loader, cn) */ static Object instantiate(ClassLoader loader, String cn) throws IOException, ClassNotFoundException { Exception exception; if (instantiateMethod != null) { // invoke Beans.instantiate try { return instantiateMethod.invoke(null, loader, cn); } catch (InvocationTargetException e) { exception = e; } catch (IllegalAccessException e) { exception = e; } } else { SecurityManager security = System.getSecurityManager(); if (security != null) { // if it's ok with the SecurityManager, it's ok with me. String cname = cn.replace('/', '.'); if (cname.startsWith("[")) { int b = cname.lastIndexOf('[') + 2; if (b > 1 && b < cname.length()) { cname = cname.substring(b); } } int i = cname.lastIndexOf('.'); if (i != -1) { security.checkPackageAccess(cname.substring(0, i)); } } // Beans.instantiate specified to use SCL when loader is null if (loader == null) { loader = (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() { public Object run() { ClassLoader cl = null; try { cl = ClassLoader.getSystemClassLoader(); } catch (SecurityException ex) { } return cl; } }); } Class beanClass = Class.forName(cn, true, loader); try { return beanClass.newInstance(); } catch (Exception ex) { throw new ClassNotFoundException(beanClass + ": " + ex, ex); } } return null; } } }





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