Tomcat example source code file (ReplicationStream.java)

This example Tomcat source code file (ReplicationStream.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

class, class, classloader, classnotfoundexception, classnotfoundexception, exception, io, ioexception, ioexception, objectinputstream, replicationstream, replicationstream, string

The Tomcat ReplicationStream.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (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.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.catalina.tribes.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;

/**
 * Custom subclass of <code>ObjectInputStream that loads from the
 * class loader for this web application.  This allows classes defined only
 * with the web application to be found correctly.
 *
 * @author Craig R. McClanahan
 * @author Bip Thelin
 * @author Filip Hanik
 * @version $Revision: 467173 $, $Date: 2006-10-24 01:12:17 +0200 (mar., 24 oct. 2006) $
 */

public final class ReplicationStream extends ObjectInputStream {

    
    /**
     * The class loader we will use to resolve classes.
     */
    private ClassLoader[] classLoaders = null;
    

    /**
     * Construct a new instance of CustomObjectInputStream
     *
     * @param stream The input stream we will read from
     * @param classLoader The class loader used to instantiate objects
     *
     * @exception IOException if an input/output error occurs
     */
    public ReplicationStream(InputStream stream,
                             ClassLoader[] classLoaders)
        throws IOException {

        super(stream);
        this.classLoaders = classLoaders;
    }

    /**
     * Load the local class equivalent of the specified stream class
     * description, by using the class loader assigned to this Context.
     *
     * @param classDesc Class description from the input stream
     *
     * @exception ClassNotFoundException if this class cannot be found
     * @exception IOException if an input/output error occurs
     */
    public Class resolveClass(ObjectStreamClass classDesc)
        throws ClassNotFoundException, IOException {
        String name = classDesc.getName();
        boolean tryRepFirst = name.startsWith("org.apache.catalina.tribes");
        try {
            try
            {
                if ( tryRepFirst ) return findReplicationClass(name);
                else return findExternalClass(name);
            }
            catch ( Exception x )
            {
                if ( tryRepFirst ) return findExternalClass(name);
                else return findReplicationClass(name);
            }
        } catch (ClassNotFoundException e) {
            return super.resolveClass(classDesc);
        }
    }
    
    public Class findReplicationClass(String name)
        throws ClassNotFoundException, IOException {
        Class clazz = Class.forName(name, false, getClass().getClassLoader());
        return clazz;
    }

    public Class findExternalClass(String name) throws ClassNotFoundException  {
        ClassNotFoundException cnfe = null;
        for (int i=0; i<classLoaders.length; i++ ) {
            try {
                Class clazz = Class.forName(name, false, classLoaders[i]);
                return clazz;
            } catch ( ClassNotFoundException x ) {
                cnfe = x;
            } 
        }
        if ( cnfe != null ) throw cnfe;
        else throw new ClassNotFoundException(name);
    }
    
    public void close() throws IOException  {
        this.classLoaders = null;
        super.close();
    }


}