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

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

Go to download

This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

There is a newer version: 34.0.0.Final
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:
 *
 *   https://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.ByteBuf;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.util.internal.TypeParameterMatcher;

import java.util.List;

/**
 * A Codec for on-the-fly encoding/decoding of bytes to messages and vise-versa.
 *
 * This can be thought of as a combination of {@link ByteToMessageDecoder} and {@link MessageToByteEncoder}.
 *
 * Be aware that sub-classes of {@link ByteToMessageCodec} MUST NOT
 * annotated with {@link @Sharable}.
 */
public abstract class ByteToMessageCodec extends ChannelDuplexHandler {

    private final TypeParameterMatcher outboundMsgMatcher;
    private final MessageToByteEncoder encoder;

    private final ByteToMessageDecoder decoder = new ByteToMessageDecoder() {
        @Override
        public void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception {
            ByteToMessageCodec.this.decode(ctx, in, out);
        }

        @Override
        protected void decodeLast(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception {
            ByteToMessageCodec.this.decodeLast(ctx, in, out);
        }
    };

    /**
     * see {@link #ByteToMessageCodec(boolean)} with {@code true} as boolean parameter.
     */
    protected ByteToMessageCodec() {
        this(true);
    }

    /**
     * see {@link #ByteToMessageCodec(Class, boolean)} with {@code true} as boolean value.
     */
    protected ByteToMessageCodec(Class outboundMessageType) {
        this(outboundMessageType, true);
    }

    /**
     * Create a new instance which will try to detect the types to match out of the type parameter of the class.
     *
     * @param preferDirect          {@code true} if a direct {@link ByteBuf} should be tried to be used as target for
     *                              the encoded messages. If {@code false} is used it will allocate a heap
     *                              {@link ByteBuf}, which is backed by an byte array.
     */
    protected ByteToMessageCodec(boolean preferDirect) {
        ensureNotSharable();
        outboundMsgMatcher = TypeParameterMatcher.find(this, ByteToMessageCodec.class, "I");
        encoder = new Encoder(preferDirect);
    }

    /**
     * Create a new instance
     *
     * @param outboundMessageType   The type of messages to match
     * @param preferDirect          {@code true} if a direct {@link ByteBuf} should be tried to be used as target for
     *                              the encoded messages. If {@code false} is used it will allocate a heap
     *                              {@link ByteBuf}, which is backed by an byte array.
     */
    protected ByteToMessageCodec(Class outboundMessageType, boolean preferDirect) {
        ensureNotSharable();
        outboundMsgMatcher = TypeParameterMatcher.get(outboundMessageType);
        encoder = new Encoder(preferDirect);
    }

    /**
     * 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);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        decoder.channelRead(ctx, msg);
    }

    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        encoder.write(ctx, msg, promise);
    }

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

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

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        try {
            decoder.handlerAdded(ctx);
        } finally {
            encoder.handlerAdded(ctx);
        }
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        try {
            decoder.handlerRemoved(ctx);
        } finally {
            encoder.handlerRemoved(ctx);
        }
    }

    /**
     * @see MessageToByteEncoder#encode(ChannelHandlerContext, Object, ByteBuf)
     */
    protected abstract void encode(ChannelHandlerContext ctx, I msg, ByteBuf out) throws Exception;

    /**
     * @see ByteToMessageDecoder#decode(ChannelHandlerContext, ByteBuf, List)
     */
    protected abstract void decode(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception;

    /**
     * @see ByteToMessageDecoder#decodeLast(ChannelHandlerContext, ByteBuf, List)
     */
    protected void decodeLast(ChannelHandlerContext ctx, ByteBuf in, List out) throws Exception {
        if (in.isReadable()) {
            // Only call decode() if there is something left in the buffer to decode.
            // See https://github.com/netty/netty/issues/4386
            decode(ctx, in, out);
        }
    }

    private final class Encoder extends MessageToByteEncoder {
        Encoder(boolean preferDirect) {
            super(preferDirect);
        }

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

        @Override
        protected void encode(ChannelHandlerContext ctx, I msg, ByteBuf out) throws Exception {
            ByteToMessageCodec.this.encode(ctx, msg, out);
        }
    }
}
    

    

    

            

    

            



    
    






    
© 2015 - 2024 Weber Informatics LLC | Privacy Policy