25.ByteToMessageDecoderReplaying

ByteToMessageDecoderReplayingDecoder<Void>、MessageToByteEncoder<Long>、MessageToMessageDecoder<Long>

1.Server端

public class MyServer {

    public static void main(String[] args) throws Exception {
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        try {
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class).
                    childHandler(new MyServerInitializer());

            ChannelFuture channelFuture = serverBootstrap.bind(8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

2.ServerInitializer

public class MyServerInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new MyByteToLongDecoder2());
        pipeline.addLast(new MyLongToStringDecoder());
        pipeline.addLast(new MyLongToByteEncoder());
        pipeline.addLast(new MyServerHandler());
    }
}
        

3.Client端

public class MyClient {

    public static void main(String[] args) throws Exception{
        EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(eventLoopGroup).channel(NioSocketChannel.class).
                    handler(new MyClientInitializer());

            ChannelFuture channelFuture = bootstrap.connect("localhost", 8899).sync();
            channelFuture.channel().closeFuture().sync();
        } finally {
            eventLoopGroup.shutdownGracefully();
        }
    }
}

4.Client端的ServerInitializer

public class MyClientInitializer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new MyByteToLongDecoder2());
        pipeline.addLast(new MyLongToByteEncoder());
        pipeline.addLast(new MyClientHandler());
    }
}

5.入站出站编码器解码器

public class MyByteToLongDecoder2 extends ReplayingDecoder<Void> {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        System.out.println("MyByteToLongDecoder2 decode invoked!");

        out.add(in.readLong());
    }
}

public class MyLongToStringDecoder extends MessageToMessageDecoder<Long> {

    @Override
    protected void decode(ChannelHandlerContext ctx, Long msg, List<Object> out) throws Exception {
        System.out.println("MyLongToStringDecoder decode invoked!");
        out.add(String.valueOf(msg));
    }
}

public class MyLongToByteEncoder extends MessageToByteEncoder<Long>{

    @Override
    protected void encode(ChannelHandlerContext ctx, Long msg, ByteBuf out) throws Exception {
        System.out.println("encode invoked!");

        System.out.println(msg);

        out.writeLong(msg);
    }
}

public class MyServerHandler extends SimpleChannelInboundHandler<String> {

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        System.out.println(ctx.channel().remoteAddress() + ", " + msg);

        ctx.writeAndFlush(654321L);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

有问题的编解码

public class MyByteToLongDecoder extends ByteToMessageDecoder {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
        System.out.println("decode invoked!");

        System.out.println(in.readableBytes());

        if (in.readableBytes() >= 8) {
            out.add(in.readLong());
        }
    }
}

public class MyLongToByteEncoder extends MessageToByteEncoder<Long>{

    @Override
    protected void encode(ChannelHandlerContext ctx, Long msg, ByteBuf out) throws Exception {
        System.out.println("encode invoked!");

        System.out.println(msg);

        out.writeLong(msg);
    }
}