scriptableinputstream.java

javascript语言的解释器源码

/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is Rhino serialization code, released
 * Sept. 25, 2001.
 *
 * The Initial Developer of the Original Code is Norris Boyd.
 *
 * Contributor(s):
 * Norris Boyd
 * Igor Bukanov
 * Attila Szegedi
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU Public License (the "GPL"), in which case the
 * provisions of the GPL are applicable instead of those above.
 * If you wish to allow use of your version of this file only
 * under the terms of the GPL and not to allow others to use your
 * version of this file under the NPL, indicate your decision by
 * deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL.  If you do not delete
 * the provisions above, a recipient may use your version of this
 * file under either the NPL or the GPL.
 */

// API class

package org.mozilla.javascript.serialize;

import java.io.*;

import org.mozilla.javascript.*;

/**
 * Class ScriptableInputStream is used to read in a JavaScript
 * object or function previously serialized with a ScriptableOutputStream.
 * References to names in the exclusion list
 * replaced with references to the top-level scope specified during
 * creation of the ScriptableInputStream.
 *
 * @author Norris Boyd
 */

public class ScriptableInputStream extends ObjectInputStream {

    /**
     * Create a ScriptableInputStream.
     * @param in the InputStream to read from.
     * @param scope the top-level scope to create the object in.
     */
    public ScriptableInputStream(InputStream in, Scriptable scope)
        throws IOException
    {
        super(in);
        this.scope = scope;
        enableResolveObject(true);
        Context cx = Context.getCurrentContext();
        if (cx != null) {
            this.classLoader = cx.getApplicationClassLoader();
        }
    }

    protected Class resolveClass(ObjectStreamClass desc)
        throws IOException, ClassNotFoundException
    {
        String name = desc.getName();
        if (classLoader != null) {
            try {
                return classLoader.loadClass(name);
            } catch (ClassNotFoundException ex) {
                // fall through to default loading
            }
        }
        return super.resolveClass(desc);
    }

    protected Object resolveObject(Object obj)
        throws IOException
    {
        if (obj instanceof ScriptableOutputStream.PendingLookup) {
            String name = ((ScriptableOutputStream.PendingLookup)obj).getName();
            obj = ScriptableOutputStream.lookupQualifiedName(scope, name);
            if (obj == Scriptable.NOT_FOUND) {
                throw new IOException("Object " + name + " not found upon " +
                                      "deserialization.");
            }
        }else if (obj instanceof UniqueTag) {
            obj = ((UniqueTag)obj).readResolve();
        }else if (obj instanceof Undefined) {
            obj = ((Undefined)obj).readResolve();
        }
        return obj;
    }

    private Scriptable scope;
    private ClassLoader classLoader;
}