objectserializationencoder.java

mina是以Java实现的一个开源的网络程序框架

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 *  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.mina.filter.codec.serialization;

import java.io.NotSerializableException;
import java.io.Serializable;

import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolEncoder;
import org.apache.mina.filter.codec.ProtocolEncoderAdapter;
import org.apache.mina.filter.codec.ProtocolEncoderOutput;

/**
 * A {@link ProtocolEncoder} which serializes {@link Serializable} Java objects
 * using {@link IoBuffer#putObject(Object)}.
 *
 * @author The Apache MINA Project ([e-mail])
 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (Thu, 26 Jun 2008) $
 */
public class ObjectSerializationEncoder extends ProtocolEncoderAdapter {
    private int maxObjectSize = Integer.MAX_VALUE; // 2GB

    /**
     * Creates a new instance.
     */
    public ObjectSerializationEncoder() {
    }

    /**
     * Returns the allowed maximum size of the encoded object.
     * If the size of the encoded object exceeds this value, this encoder
     * will throw a {@link IllegalArgumentException}.  The default value
     * is {@link Integer#MAX_VALUE}.
     */
    public int getMaxObjectSize() {
        return maxObjectSize;
    }

    /**
     * Sets the allowed maximum size of the encoded object.
     * If the size of the encoded object exceeds this value, this encoder
     * will throw a {@link IllegalArgumentException}.  The default value
     * is {@link Integer#MAX_VALUE}.
     */
    public void setMaxObjectSize(int maxObjectSize) {
        if (maxObjectSize <= 0) {
            throw new IllegalArgumentException("maxObjectSize: "
                    + maxObjectSize);
        }

        this.maxObjectSize = maxObjectSize;
    }

    public void encode(IoSession session, Object message,
            ProtocolEncoderOutput out) throws Exception {
        if (!(message instanceof Serializable)) {
            throw new NotSerializableException();
        }

        IoBuffer buf = IoBuffer.allocate(64);
        buf.setAutoExpand(true);
        buf.putObject(message);

        int objectSize = buf.position() - 4;
        if (objectSize > maxObjectSize) {
            throw new IllegalArgumentException(
                    "The encoded object is too big: " + objectSize + " (> "
                            + maxObjectSize + ')');
        }

        buf.flip();
        out.write(buf);
    }
}