All Downloads are FREE. Search and download functionalities are using the official Maven repository.

io.netty.handler.codec.MessageToMessageCodec Maven / Gradle / Ivy

Go to download

There is a newer version: 5.0.0.Alpha2
Show newest version
/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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 io.netty.handler.codec;

import io.netty.buffer.MessageBuf;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundMessageHandler;
import io.netty.channel.ChannelOutboundMessageHandler;
import io.netty.channel.ChannelPromise;
import io.netty.util.internal.TypeParameterMatcher;

/**
 * A Codec for on-the-fly encoding/decoding of message.
 *
 * This can be thought of as a combination of {@link MessageToMessageDecoder} and {@link MessageToMessageEncoder}.
 *
 * Here is an example of a {@link MessageToMessageCodec} which just decode from {@link Integer} to {@link Long}
 * and encode from {@link Long} to {@link Integer}.
 *
 * 
 *     public class NumberCodec extends
 *             {@link MessageToMessageCodec}<{@link Integer}, {@link Long}, {@link Long}, {@link Integer}> {
 *         {@code @Override}
 *         public {@link Long} decode({@link ChannelHandlerContext} ctx, {@link Integer} msg)
 *                 throws {@link Exception} {
 *             return msg.longValue();
 *         }
 *
 *         {@code @Overrride}
 *         public {@link Integer} encode({@link ChannelHandlerContext} ctx, {@link Long} msg)
 *                 throws {@link Exception} {
 *             return msg.intValue();
 *         }
 *     }
 * 

 */
public abstract class MessageToMessageCodec
        extends ChannelDuplexHandler
        implements ChannelInboundMessageHandler,
                   ChannelOutboundMessageHandler {

    private final MessageToMessageEncoder encoder =
            new MessageToMessageEncoder() {
        @Override
        public boolean acceptOutboundMessage(Object msg) throws Exception {
            return MessageToMessageCodec.this.acceptOutboundMessage(msg);
        }

        @Override
        @SuppressWarnings("unchecked")
        protected Object encode(ChannelHandlerContext ctx, Object msg) throws Exception {
            return MessageToMessageCodec.this.encode(ctx, (OUTBOUND_IN) msg);
        }
    };

    private final MessageToMessageDecoder decoder =
            new MessageToMessageDecoder() {

        @Override
        public boolean acceptInboundMessage(Object msg) throws Exception {
            return MessageToMessageCodec.this.acceptInboundMessage(msg);
        }

        @Override
        @SuppressWarnings("unchecked")
        protected Object decode(ChannelHandlerContext ctx, Object msg) throws Exception {
            return MessageToMessageCodec.this.decode(ctx, (INBOUND_IN) msg);
        }
    };

    private final TypeParameterMatcher inboundMsgMatcher;
    private final TypeParameterMatcher outboundMsgMatcher;

    protected MessageToMessageCodec() {
        inboundMsgMatcher = TypeParameterMatcher.find(this, MessageToMessageCodec.class, "INBOUND_IN");
        outboundMsgMatcher = TypeParameterMatcher.find(this, MessageToMessageCodec.class, "OUTBOUND_IN");
    }

    @Override
    @SuppressWarnings("unchecked")
    public MessageBuf newInboundBuffer(ChannelHandlerContext ctx) throws Exception {
        return (MessageBuf) decoder.newInboundBuffer(ctx);
    }

    @Override
    public void freeInboundBuffer(ChannelHandlerContext ctx) throws Exception {
        decoder.freeInboundBuffer(ctx);
    }

    @Override
    @SuppressWarnings("unchecked")
    public MessageBuf newOutboundBuffer(ChannelHandlerContext ctx) throws Exception {
        return (MessageBuf) encoder.newOutboundBuffer(ctx);
    }

    @Override
    public void freeOutboundBuffer(ChannelHandlerContext ctx) throws Exception {
        encoder.freeOutboundBuffer(ctx);
    }

    @Override
    public void inboundBufferUpdated(
            ChannelHandlerContext ctx) throws Exception {
        decoder.inboundBufferUpdated(ctx);
    }

    @Override
    public void flush(ChannelHandlerContext ctx, ChannelPromise future) throws Exception {
        encoder.flush(ctx, future);
    }

    /**
     * Returns {@code true} if and only if the specified message can be decoded by this codec.
     *
     * @param msg the message
     */
    public boolean acceptInboundMessage(Object msg) throws Exception {
        return inboundMsgMatcher.match(msg);
    }

    /**
     * Returns {@code true} if and only if the specified message can be encoded by this codec.
     *
     * @param msg the message
     */
    public boolean acceptOutboundMessage(Object msg) throws Exception {
        return outboundMsgMatcher.match(msg);
    }

    protected abstract Object encode(ChannelHandlerContext ctx, OUTBOUND_IN msg) throws Exception;
    protected abstract Object decode(ChannelHandlerContext ctx, INBOUND_IN msg) throws Exception;
}
 















© 2015 - 2024 Weber Informatics LLC | Privacy Policy