Externalizer.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2014 Red Hat, Inc., and individual contributors
 * as indicated by the @author tags.
 *
 * Licensed 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.jboss.marshalling;

import java.io.IOException;
import java.io.ObjectOutput;
import java.io.ObjectInput;
import java.io.Serializable;

/**
 * A replacement serializer for an object class.
 */
public interface Externalizer extends Serializable {
    /**
     * Write the external representation of an object.  The object's class and the externalizer's class will
     * already have been written.
     *
     * @param subject the object to externalize
     * @param output the output
     * @throws IOException if an error occurs
     */
    void writeExternal(Object subject, ObjectOutput output) throws IOException;

    /**
     * Create an instance of a type.  The object may then be initialized from {@code input}, or that may be deferred
     * to the {@code readExternal()} method.  Instances may simply delegate the task to the given {@code Creator}.
     * Note that this method is called only on the leaf class, so externalizers for non-final classes that initialize
     * the instance from the stream need to be aware of this.
     *
     * @param subjectType the type of object to create
     * @param input the input
     * @return the new instance
     * @throws IOException if an error occurs
     * @throws ClassNotFoundException if a class could not be found during read
     */
    Object createExternal(Class<?> subjectType, ObjectInput input) throws IOException, ClassNotFoundException;
}