org.tiger.netty.rpc.all.codec.MarshallingEncoder.java Source code

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Here is the source code for org.tiger.netty.rpc.all.codec.MarshallingEncoder.java

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/*
 * Copyright 2013-2018 Lilinfeng.
 *  
 * 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.tiger.netty.rpc.all.codec;

import org.jboss.marshalling.Marshaller;

import java.io.IOException;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler.Sharable;

/**
 * @author Lilinfeng
 * @date 2014314
 * @version 1.0
 */
@Sharable
public class MarshallingEncoder {

    private static final byte[] LENGTH_PLACEHOLDER = new byte[4];
    Marshaller marshaller;

    public MarshallingEncoder() throws IOException {
        marshaller = MarshallingCodecFactory.buildMarshalling();
    }

    protected void encode(Object msg, ByteBuf out) throws Exception {
        try {
            int lengthPos = out.writerIndex();
            out.writeBytes(LENGTH_PLACEHOLDER);//??
            ChannelBufferByteOutput output = new ChannelBufferByteOutput(out);
            marshaller.start(output);
            marshaller.writeObject(msg);
            marshaller.finish();
            //ByteBufsetInt(int index, int value):indexvalueint
            //?ByteBufwriteIntsetInt??readerIndexwriterIndex
            //??4??
            out.setInt(lengthPos, out.writerIndex() - lengthPos - 4);
        } finally {
            marshaller.close();
        }
    }
}