netty5自定义私有协议实例

  一般业务需求都会自行定义私有协议来满足自己的业务场景,私有协议也可以解决粘包和拆包问题,比如客户端发送数据时携带数据包长度,服务端接收数据后解析消息体,获取数据包长度值,据此继续获取数据包内容。我们来看具体例子,自定义的协议如下:

  +--------------------------------------------------+----------+
   |                消息头                         |     消息体 |
   | Delimiter | Length | Type | Reserved      |       data   |
   +-------------------------------------------------+----------+

  

  1)      Delimiter4bytes,消息头,用于分割消息。

  2)      Length:数据长度。

  3)      Type:1bytes,消息类型 

  4)      Reserved:1bytes,保留。

  5)      Data包数据

  接下来看如何实现编解码:

  1、先定义好javabean:

  总体的:

package com.wlf.netty.nettyapi.javabean;

import lombok.Getter;
import lombok.Setter;

@Setter
@Getter
public class NettyMessage {

    private Header header;

    private byte[] data;

    @Override
    public String toString() {
        return "NettyMessage{" +
                "header=" + header +
                ", data=" + data +
                '}';
    }
}

  头的:

package com.wlf.netty.nettyapi.javabean;

import lombok.Getter;
import lombok.Setter;

@Getter
@Setter
public class Header {

    /**
     * 4bytes,消息头,用于分割消息。如0xABEF0101
     */
    private int delimiter;

    /**
     * 1byte,类型
     */
    private byte type;

    /**
     * 1byte,保留
     */
    private byte reserved;

    /**
     * 数据长度
     */
    private int length;

    @Override
    public String toString() {
        return "Header{" +
                "delimiter=" + delimiter +
                ", length=" + length +
                ", type=" + type +
                ", reserved=" + reserved +
                '}';
    }
}

  2、编码:

package com.wlf.netty.nettyapi.msgpack;

import com.wlf.netty.nettyapi.javabean.NettyMessage;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

public class NettyMessageEncoder extends MessageToByteEncoder<NettyMessage> {

    @Override
    protected void encode(ChannelHandlerContext channelHandlerContext, NettyMessage nettyMessage, ByteBuf byteBuf) throws Exception {

        if (nettyMessage == null || nettyMessage.getHeader() == null) {
            throw new Exception("The nettyMessage is null.");
        }

        // 1、写入分割标志
        byteBuf.writeInt(nettyMessage.getHeader().getDelimiter());

        // 2、写入数据包长度
        byteBuf.writeInt(nettyMessage.getData() != null ? nettyMessage.getData().length : 0);

        // 3、写入请求类型
        byteBuf.writeByte(nettyMessage.getHeader().getType());

        // 4、写入预留字段
        byteBuf.writeByte(nettyMessage.getHeader().getReserved());

        // 5、写入数据
        byteBuf.writeBytes(nettyMessage.getData() != null ? nettyMessage.getData() : null);

    }
}

  3、解码:

package com.wlf.netty.nettyapi.msgpack;

import com.wlf.netty.nettyapi.constant.Delimiter;
import com.wlf.netty.nettyapi.javabean.Header;
import com.wlf.netty.nettyapi.javabean.NettyMessage;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;

import java.util.List;

public class NettyMessageDecoder extends ByteToMessageDecoder {

    /**
     * 消息体字节大小:分割符字段4字节+长度字段4字节+请求类型字段1字节+预留字段1字节=10字节
     */
    private static final int HEAD_LENGTH = 10;

    @Override
    protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception {

        // 字节流开始位置
        int packStartIndex;
        while (true) {

            // 获取字节流开始位置
            packStartIndex = byteBuf.readerIndex();

            // 若读取到分割标识,说明读取当前字节流开始位置了
            if (byteBuf.readInt() == Delimiter.DELIMITER) {
                break;
            }

            // 重置读索引为0
            byteBuf.resetReaderIndex();

            // 长度校验,字节流长度至少10字节,小于10字节则等待下一次字节流过来
            if (byteBuf.readableBytes() < HEAD_LENGTH) {
                return;
            }
        }

        // 2、获取data的字节流长度
        int dataLength = byteBuf.readInt();

        // 校验数据包是否全部发送过来,总字节流长度(此处读取的是除去delimiter和length之后的总长度)减去type和reserved两个字节=data的字节流长度
        int totalLength = byteBuf.readableBytes();
        if ((totalLength - 2) < dataLength) {

            // 长度校验,字节流长度少于data数据包长度,说明数据包拆包了,等待下一次字节流过来
            byteBuf.readerIndex(packStartIndex);
            return;
        }

        // 3、请求类型
        byte type = byteBuf.readByte();

        // 4、预留字段
        byte reserved = byteBuf.readByte();


        // 5、数据包内容
        byte[] data = null;
        if (dataLength > 0) {
            data = new byte[dataLength];
            byteBuf.readBytes(data);
        }

        NettyMessage nettyMessage = new NettyMessage();
        Header header = new Header();
        header.setDelimiter(0xABEF0101);
        header.setLength(dataLength);
        header.setType(type);
        header.setReserved(reserved);
        nettyMessage.setHeader(header);
        nettyMessage.setData(data);

        list.add(nettyMessage);

        // 回收已读字节
        byteBuf.discardReadBytes();
    }
}

  为了运行,我们需要写客户端和服务端的handler:

  4、客户端handler:

package com.wlf.netty.nettyclient.handler;

import com.wlf.netty.nettyapi.constant.Delimiter;
import com.wlf.netty.nettyapi.constant.MessageType;
import com.wlf.netty.nettyapi.javabean.Header;
import com.wlf.netty.nettyapi.javabean.NettyMessage;
import com.wlf.netty.nettyapi.util.CommonUtil;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.ArrayUtils;

import java.io.RandomAccessFile;
import java.util.Arrays;

/**
 * 客户端处理类
 */
@Slf4j
public class NettyClientHandler extends ChannelHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        ctx.writeAndFlush(buildClientRequest());
    }

    /**
     * 创建请求消息体
     *
     * @return
     */
    private NettyMessage buildClientRequest() {
        NettyMessage nettyMessage = new NettyMessage();
        Header header = new Header();
        byte[] data = new byte[0];
        try {
            data = buildPcmData();
        } catch (Exception e) {
            e.printStackTrace();
        }
        header.setDelimiter(0xABEF0101);
        header.setLength(data.length);
        header.setType((byte) 1);
        header.setReserved((byte) 0);
        nettyMessage.setHeader(header);

        // 设置数据包
        nettyMessage.setData(data);
        return nettyMessage;
    }

    /**
     * 构造PCM请求消息体
     *
     * @return
     */
    private byte[] buildPcmData() throws Exception {
        byte[] resultByte = longToBytes(System.currentTimeMillis());

        return resultByte;
    }

    /**
     * long转字节
     *
     * @param values
     * @return
     */
    private byte[] longToBytes(long values) {
        byte[] buffer = new byte[8];
        for (int i = 0; i < 8; i++) {
            int offset = 64 - (i + 1) * 8;
            buffer[i] = (byte) ((values >> offset) & 0xff);
        }
        return buffer;
    }

    /**
     * 将两个数组合并起来
     *
     * @param array1
     * @param array2
     * @return
     */
    private byte[] addAll(byte[] array1, byte... array2) {
        byte[] joinedArray = new byte[array1.length + array2.length];
        System.arraycopy(array1, 0, joinedArray, 0, array1.length);
        System.arraycopy(array2, 0, joinedArray, array1.length, array2.length);
        return joinedArray;
    }

    /**
     * 在处理过程中引发异常时被调用
     *
     * @param ctx
     * @param cause
     * @throws Exception
     */
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        log.error("[Client] netty client request error: {}", cause.getMessage());
        ctx.close();
    }



}

  5、服务端handler:

package com.wlf.netty.nettyserver.handler;

import com.alibaba.fastjson.JSON;
import com.wlf.netty.nettyapi.constant.MessageType;
import com.wlf.netty.nettyapi.javabean.NettyMessage;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import lombok.extern.slf4j.Slf4j;


@Slf4j
public class NettyServerHandler extends ChannelHandlerAdapter {


    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        NettyMessage nettyMessage = (NettyMessage) msg;

        if (nettyMessage.getHeader() != null && nettyMessage.getHeader().getType() == (byte) 1) {
            log.info("[server] server receive client message : {}", nettyMessage);
            if (nettyMessage == null || nettyMessage.getData() == null) {
                log.error("nettyMessage is null.");
            }

            // 获取时间戳(8字节)
            byte[] data = nettyMessage.getData();
            ByteBuf buf = Unpooled.buffer(data.length);
            buf.writeBytes(data);
            long startTime = buf.readLong();
            log.info("data length: {}", data.length);
            log.info("startTime: {}", startTime);

        }
    }


    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        log.error("server received failed, error : {}", cause.getMessage());
        cause.printStackTrace();
        ctx.close();
    }


}

  最后,为了启动,我们还得再补两个启动类:

  6、客户端:

package com.wlf.netty.nettyclient.client;

import com.wlf.netty.nettyapi.msgpack.NettyMessageDecoder;
import com.wlf.netty.nettyapi.msgpack.NettyMessageEncoder;
import com.wlf.netty.nettyclient.handler.NettyClientHandler;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import lombok.extern.slf4j.Slf4j;

import java.net.InetSocketAddress;

/**
 * 客户端
 * 1.为初始化客户端,创建一个Bootstrap实例
 * 2.为进行事件处理分配了一个NioEventLoopGroup实例,其中事件处理包括创建新的连接以及处理入站和出站数据;
 * 3.当连接被建立时,一个NettyClientHandler实例会被安装到(该Channel的一个ChannelPipeline中;
 * 4.在一切都设置完成后,调用Bootstrap.connect()方法连接到远程节点。
 */
@Slf4j
public class NettyClient {

    private ScheduledExecutorService executorService = Executors.newScheduledThreadPool(1);

    EventLoopGroup group = new NioEventLoopGroup();

    public void connect(int port, String host) throws Exception {
        NioEventLoopGroup workGroup = new NioEventLoopGroup();
        try {
            Bootstrap bootstrap = new Bootstrap();
            bootstrap.group(workGroup).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel channel) throws Exception {
                            channel.pipeline().addLast(new NettyMessageDecoder());
                            channel.pipeline().addLast(new NettyMessageEncoder());
                            channel.pipeline().addLast(new NettyClientHandler());
                        }
                    });
            ChannelFuture future = bootstrap.connect(host, port).sync();
            future.channel().closeFuture().sync();
        } finally {
            workGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        int port = 9911;
        new NettyClient().connect(port, "127.0.0.1");
    }
}

  7、服务端启动类:

package com.wlf.netty.nettyserver.server;

import com.wlf.netty.nettyapi.msgpack.NettyMessageDecoder;
import com.wlf.netty.nettyapi.msgpack.NettyMessageEncoder;
import com.wlf.netty.nettyserver.handler.NettyServerHandler;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;import lombok.extern.slf4j.Slf4j;


@Slf4j
public class NettyServer {

    private final EventLoopGroup bossGroup = new NioEventLoopGroup();
    private final EventLoopGroup workGroup = new NioEventLoopGroup();

    public void bind(int port) throws Exception{
        try{
            ServerBootstrap serverBootstrap = new ServerBootstrap();
            serverBootstrap.group(bossGroup, workGroup).channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        public void initChannel(SocketChannel channel) throws Exception {
                            channel.pipeline().addLast(new NettyMessageDecoder());
                            channel.pipeline().addLast(new NettyMessageEncoder());                            
                            channel.pipeline().addLast(new NettyServerHandler());
                        }
                    });
            // 绑定端口
            ChannelFuture channelFuture = serverBootstrap.bind(port).sync();
            channelFuture.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }

    public static void main(String[] args) throws Exception {
        int port = 9911;
        new NettyServer().bind(port);
    }

    
}

  直接跑上面两个启动类,先跑服务端,再跑客户端:

  客户端输出:

17:20:04.258 [nioEventLoopGroup-1-1] INFO com.wlf.netty.nettyclient.handler.NettyClientHandler - [client] client send data : NettyMessage{header=Header{delimiter=-1410399999, length=8, type=1, reserved=0}, data=[B@432f82d5}

  服务端输出:

17:20:04.295 [nioEventLoopGroup-1-1] INFO com.wlf.netty.nettyserver.handler.NettyServerHandler - [server] server receive client message : NettyMessage{header=Header{delimiter=-1410399999, length=8, type=1, reserved=0}, data=[B@16eddbb3}
17:20:04.295 [nioEventLoopGroup-1-0] INFO com.wlf.netty.nettyserver.handler.NettyServerHandler - data length: 8
17:20:04.295 [nioEventLoopGroup-1-1] INFO com.wlf.netty.nettyserver.handler.NettyServerHandler - startTime: 1570785604258

   以上解码在字节流总容量小于1024时都没问题,但超过就会出现服务端获取不到数据的问题,详情和解决办法请参见netty5拆包问题解决实例

  

posted on 2019-10-11 17:22  不想下火车的人  阅读(1007)  评论(1编辑  收藏  举报

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