OpencronDecoder.java

/**
 * Copyright 2016 benjobs
 * <p>
 * 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.opencron.common.serialization;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;

import java.io.IOException;

/**
 * ${DESCRIPTION}
 *
 * @author Ricky Fung
 */
public class OpencronDecoder<T> extends LengthFieldBasedFrameDecoder {

    private Serializer serializer = new HessianSerializer();
    private Class<T> type;

    public OpencronDecoder(Class<T> type, int maxFrameLength, int lengthFieldOffset, int lengthFieldLength) throws IOException {
        super(maxFrameLength, lengthFieldOffset, lengthFieldLength);
        this.type = type;
    }

    @Override
    protected Object decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {

        ByteBuf buffer = (ByteBuf) super.decode(ctx, in);
        if (buffer == null) {
            return null;
        }
        if (buffer.readableBytes() < 4) {
            throw new Exception("error");
        }

        int length = buffer.readInt();

        byte[] data = new byte[length];
        buffer.readBytes(data);

        return serializer.decode(data, type);
    }
}