Netty 集成google ProtoBuf 开发私有协议之实战开发

- 日理万妓 2023-10-10 12:15 2阅读 0赞

本文基于[Netty 集成google ProtoBuf 开发私有协议][Netty _google ProtoBuf],进行实战功能开发

本文参考借鉴:[https://blog.csdn.net/kunfeisang5551/article/details/107957256][https_blog.csdn.net_kunfeisang5551_article_details_107957256]

## 第一步：新建自定义协议文本对象User.proto ##

syntax = "proto3";
    //生成的包名，此处根据实际来修改
    option java_package = "com.netty.protobuf";
    //类名
    option java_outer_classname="UserInfo";
    
    message UserMsg{
      int32 id=1;
      string name=2;
      int32 age=3;
      int32 state=4;
    }

## 第二步：Java 项目集成Google ProtoBuf 功能添加如下jar 包依赖 ##

<dependencies>
    	    
    		<dependency>
    			<groupId>io.netty</groupId>
    			<artifactId>netty-all</artifactId>
    			<version>4.1.42.Final</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>com.google.protobuf</groupId>
    			<artifactId>protobuf-java</artifactId>
    			<version>3.11.0</version>
    		</dependency>
    	</dependencies>

## 第三步:新建Netty 服务端程序启动入口及其消息处理器(Handler) ##

服务端代码:EchoServer.java

package com.netty.server.two;
    
    import com.netty.protobuf.UserInfo;
    import com.netty.server.two.handler.EchoServerHandler;
    import io.netty.bootstrap.ServerBootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioServerSocketChannel;
    import io.netty.handler.codec.protobuf.ProtobufDecoder;
    import io.netty.handler.codec.protobuf.ProtobufEncoder;
    import io.netty.handler.codec.protobuf.ProtobufVarint32FrameDecoder;
    import io.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender;
    import io.netty.handler.logging.LogLevel;
    import io.netty.handler.logging.LoggingHandler;
    
    public class EchoServer {
    	private int port=8081;
    	private void run() {
    		  EventLoopGroup bossGroup = new NioEventLoopGroup();
    	      EventLoopGroup workerGroup = new NioEventLoopGroup();
    	        try {
    	            //创建ServerBootstrap对象，它是Netty用于启动NIO服务端的辅助启动类，目的是降低服务端的开发复杂度。
    	            ServerBootstrap bootstrap = new ServerBootstrap();
    
    	            bootstrap
    	                    //调用ServerBootstrap的group方法，将两个NIO线程组当作入参传递到ServerBootstrap中。
    	                    .group(bossGroup, workerGroup)
    	                    //接着设置创建的Channel为NioServerSocketChannel,它的功能对应于JDK NIO类库中的ServerSocketChannel类。
    	                    .channel(NioServerSocketChannel.class)
    	                    .handler(new LoggingHandler(LogLevel.INFO))
    	                    //最后绑定I/O事件的处理类ChannelInitializer，它的作用类似于Reactor模式中的Handler类，
    	                    //主要用于处理网络I/O事件，例如记录日志、对消息进行编解码等。
    	                    .childHandler(new ChannelInitializer<SocketChannel>() {
    	                        @Override
    	                        protected void initChannel(SocketChannel socketChannel) throws Exception {
    	                            socketChannel.pipeline()
    	                                    //创建消息解码器，获取消息长度
    	                                    .addLast(new ProtobufVarint32FrameDecoder())
    	                                    //指定消息类型
    	                                    .addLast(new ProtobufDecoder(UserInfo.UserMsg.getDefaultInstance()))
    	                                    //消息头置长度
    	                                    .addLast(new ProtobufVarint32LengthFieldPrepender())
    	                                    //创建消息编码器
    	                                    .addLast(new ProtobufEncoder())
    	                                    //消息的处理
    	                                    .addLast(new EchoServerHandler());
    	                        }
    	                    });
    	            //服务端启动辅助类配置完成之后，调用它的bind 方法绑定监听端口，
    	            //随后，调用它的同步阻塞方法sync等待绑定操作完成。
    	            //完成之后Netty会返回一个ChannelFuture, 它的功能类似于JDK的java.util.concurrent.Future，主要用于异步操作的通知回调。
    	            //使用f.channel.closeFuture().syncO方法进行阻塞，等待服务端链路关闭之后main函数才退出。
    	            ChannelFuture sync = bootstrap.bind(port).sync();
    
    	            sync.channel().closeFuture().sync();
    	        } catch (Exception e) {
    	            e.printStackTrace();
    	        } finally {
    	            //调用NIO线程组的shutdownGracefully 进行优雅退出，它会释放跟shutdownGracefully相关联的资源。
    	            bossGroup.shutdownGracefully();
    	            workerGroup.shutdownGracefully();
    	        }
    
    	}
    	
    	public static void main(String[] args) {
    		new EchoServer().run();
    	}
    }

服务端消息处理器:EchoServerHandler.java

package com.netty.server.two.handler;
    
    import com.netty.protobuf.UserInfo;
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.ChannelInboundHandlerAdapter;
    import io.netty.util.ReferenceCountUtil;
    
    public class EchoServerHandler extends ChannelInboundHandlerAdapter {
    	int count;
    
    	//当通道激活时
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            System.out.println("连接的客户端地址:" + ctx.channel().remoteAddress());
            super.channelActive(ctx);
        }
    
    	//当通道读到数据时
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            try {
            	//拿到解码后的消息
            	UserInfo.UserMsg userMsg = (UserInfo.UserMsg) msg;
                System.out.println("Receive:[" + userMsg.toString() + "],count:[" + (++count) + "]");
                UserInfo.UserMsg.Builder builder =  userMsg.toBuilder().setState(1);
                ctx.writeAndFlush(builder);
            } finally {
                ReferenceCountUtil.release(msg);
            }
    
    
        }
    
    	//当通道异常时
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            cause.printStackTrace();
            ctx.close();
        }
    }

## 第四步:新建Netty 客户端程序启动入口及其消息处理器(Handler) ##

客户端程序入口:Echoclient.java

package com.netty.client.two;
    
    import com.netty.client.two.handler.EchoClientHandler;
    import com.netty.protobuf.UserInfo;
    
    import io.netty.bootstrap.Bootstrap;
    import io.netty.channel.ChannelFuture;
    import io.netty.channel.ChannelInitializer;
    import io.netty.channel.EventLoopGroup;
    import io.netty.channel.nio.NioEventLoopGroup;
    import io.netty.channel.socket.SocketChannel;
    import io.netty.channel.socket.nio.NioSocketChannel;
    import io.netty.handler.codec.protobuf.ProtobufDecoder;
    import io.netty.handler.codec.protobuf.ProtobufEncoder;
    import io.netty.handler.codec.protobuf.ProtobufVarint32FrameDecoder;
    import io.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender;
    
    public class Echoclient {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		int port = 8081;
    		EventLoopGroup group = new NioEventLoopGroup();
            try {
                Bootstrap b = new Bootstrap();
                b.group(group)
                        .channel(NioSocketChannel.class)
                        .handler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            protected void initChannel(SocketChannel socketChannel) throws Exception {
                                socketChannel.pipeline()
                                        .addLast(new ProtobufVarint32FrameDecoder())
                                        .addLast(new ProtobufDecoder(UserInfo.UserMsg.getDefaultInstance()))
                                        .addLast(new ProtobufVarint32LengthFieldPrepender())
                                        .addLast(new ProtobufEncoder())
                                        .addLast(new EchoClientHandler());
                            }
                        });
                ChannelFuture f = b.connect("127.0.0.1", port).sync();
    
                f.channel().closeFuture().sync();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                group.shutdownGracefully();
            }
    	}
    
    }

客户端消息处理器:EchoClientHandler.java

package com.netty.client.two.handler;
    
    import com.netty.protobuf.UserInfo;
    
    import io.netty.channel.ChannelHandlerContext;
    import io.netty.channel.ChannelInboundHandlerAdapter;
    import io.netty.util.ReferenceCountUtil;
    
    public class EchoClientHandler extends ChannelInboundHandlerAdapter {
    	int count;
        String echo_req = "Hi,zhouchengxi,welcome to netty";
        UserInfo.UserMsg.Builder builder = UserInfo.UserMsg.newBuilder();
    
        @Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            for (int i = 1; i <= 10; i++) {
                UserInfo.UserMsg fangyan = builder.setId(1).setAge(i).setName("zhouchengxi" + i).build();
                ctx.writeAndFlush(fangyan);
            }
        }
    
        @Override
        public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
            try {
                UserInfo.UserMsg userMsg = (UserInfo.UserMsg) msg;
                System.out.println("Server:[" + userMsg.toString() + "]count:[" + (++count) + "]");
            } finally {
                ReferenceCountUtil.release(msg);
            }
        }
    
        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            cause.printStackTrace();
            ctx.close();
        }
    }

## 第五步:自定义协议对应Java实体对象 ##

// Generated by the protocol buffer compiler.  DO NOT EDIT!
    // source: User.proto
    
    package com.netty.protobuf;
    
    public final class UserInfo {
      private UserInfo() {}
      public static void registerAllExtensions(
          com.google.protobuf.ExtensionRegistryLite registry) {
      }
    
      public static void registerAllExtensions(
          com.google.protobuf.ExtensionRegistry registry) {
        registerAllExtensions(
            (com.google.protobuf.ExtensionRegistryLite) registry);
      }
      public interface UserMsgOrBuilder extends
          // @@protoc_insertion_point(interface_extends:UserMsg)
          com.google.protobuf.MessageOrBuilder {
    
        /**
         * <code>int32 id = 1;</code>
         * @return The id.
         */
        int getId();
    
        /**
         * <code>string name = 2;</code>
         * @return The name.
         */
        java.lang.String getName();
        /**
         * <code>string name = 2;</code>
         * @return The bytes for name.
         */
        com.google.protobuf.ByteString
            getNameBytes();
    
        /**
         * <code>int32 age = 3;</code>
         * @return The age.
         */
        int getAge();
    
        /**
         * <code>int32 state = 4;</code>
         * @return The state.
         */
        int getState();
      }
      /**
       * Protobuf type {@code UserMsg}
       */
      public static final class UserMsg extends
          com.google.protobuf.GeneratedMessageV3 implements
          // @@protoc_insertion_point(message_implements:UserMsg)
          UserMsgOrBuilder {
      private static final long serialVersionUID = 0L;
        // Use UserMsg.newBuilder() to construct.
        private UserMsg(com.google.protobuf.GeneratedMessageV3.Builder<?> builder) {
          super(builder);
        }
        private UserMsg() {
          name_ = "";
        }
    
        @java.lang.Override
        @SuppressWarnings({"unused"})
        protected java.lang.Object newInstance(
            UnusedPrivateParameter unused) {
          return new UserMsg();
        }
    
        @java.lang.Override
        public final com.google.protobuf.UnknownFieldSet
        getUnknownFields() {
          return this.unknownFields;
        }
        private UserMsg(
            com.google.protobuf.CodedInputStream input,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws com.google.protobuf.InvalidProtocolBufferException {
          this();
          if (extensionRegistry == null) {
            throw new java.lang.NullPointerException();
          }
          com.google.protobuf.UnknownFieldSet.Builder unknownFields =
              com.google.protobuf.UnknownFieldSet.newBuilder();
          try {
            boolean done = false;
            while (!done) {
              int tag = input.readTag();
              switch (tag) {
                case 0:
                  done = true;
                  break;
                case 8: {
    
                  id_ = input.readInt32();
                  break;
                }
                case 18: {
                  java.lang.String s = input.readStringRequireUtf8();
    
                  name_ = s;
                  break;
                }
                case 24: {
    
                  age_ = input.readInt32();
                  break;
                }
                case 32: {
    
                  state_ = input.readInt32();
                  break;
                }
                default: {
                  if (!parseUnknownField(
                      input, unknownFields, extensionRegistry, tag)) {
                    done = true;
                  }
                  break;
                }
              }
            }
          } catch (com.google.protobuf.InvalidProtocolBufferException e) {
            throw e.setUnfinishedMessage(this);
          } catch (java.io.IOException e) {
            throw new com.google.protobuf.InvalidProtocolBufferException(
                e).setUnfinishedMessage(this);
          } finally {
            this.unknownFields = unknownFields.build();
            makeExtensionsImmutable();
          }
        }
        public static final com.google.protobuf.Descriptors.Descriptor
            getDescriptor() {
          return com.netty.protobuf.UserInfo.internal_static_UserMsg_descriptor;
        }
    
        @java.lang.Override
        protected com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
            internalGetFieldAccessorTable() {
          return com.netty.protobuf.UserInfo.internal_static_UserMsg_fieldAccessorTable
              .ensureFieldAccessorsInitialized(
                  com.netty.protobuf.UserInfo.UserMsg.class, com.netty.protobuf.UserInfo.UserMsg.Builder.class);
        }
    
        public static final int ID_FIELD_NUMBER = 1;
        private int id_;
        /**
         * <code>int32 id = 1;</code>
         * @return The id.
         */
        @java.lang.Override
        public int getId() {
          return id_;
        }
    
        public static final int NAME_FIELD_NUMBER = 2;
        private volatile java.lang.Object name_;
        /**
         * <code>string name = 2;</code>
         * @return The name.
         */
        @java.lang.Override
        public java.lang.String getName() {
          java.lang.Object ref = name_;
          if (ref instanceof java.lang.String) {
            return (java.lang.String) ref;
          } else {
            com.google.protobuf.ByteString bs = 
                (com.google.protobuf.ByteString) ref;
            java.lang.String s = bs.toStringUtf8();
            name_ = s;
            return s;
          }
        }
        /**
         * <code>string name = 2;</code>
         * @return The bytes for name.
         */
        @java.lang.Override
        public com.google.protobuf.ByteString
            getNameBytes() {
          java.lang.Object ref = name_;
          if (ref instanceof java.lang.String) {
            com.google.protobuf.ByteString b = 
                com.google.protobuf.ByteString.copyFromUtf8(
                    (java.lang.String) ref);
            name_ = b;
            return b;
          } else {
            return (com.google.protobuf.ByteString) ref;
          }
        }
    
        public static final int AGE_FIELD_NUMBER = 3;
        private int age_;
        /**
         * <code>int32 age = 3;</code>
         * @return The age.
         */
        @java.lang.Override
        public int getAge() {
          return age_;
        }
    
        public static final int STATE_FIELD_NUMBER = 4;
        private int state_;
        /**
         * <code>int32 state = 4;</code>
         * @return The state.
         */
        @java.lang.Override
        public int getState() {
          return state_;
        }
    
        private byte memoizedIsInitialized = -1;
        @java.lang.Override
        public final boolean isInitialized() {
          byte isInitialized = memoizedIsInitialized;
          if (isInitialized == 1) return true;
          if (isInitialized == 0) return false;
    
          memoizedIsInitialized = 1;
          return true;
        }
    
        @java.lang.Override
        public void writeTo(com.google.protobuf.CodedOutputStream output)
                            throws java.io.IOException {
          if (id_ != 0) {
            output.writeInt32(1, id_);
          }
          if (!getNameBytes().isEmpty()) {
            com.google.protobuf.GeneratedMessageV3.writeString(output, 2, name_);
          }
          if (age_ != 0) {
            output.writeInt32(3, age_);
          }
          if (state_ != 0) {
            output.writeInt32(4, state_);
          }
          unknownFields.writeTo(output);
        }
    
        @java.lang.Override
        public int getSerializedSize() {
          int size = memoizedSize;
          if (size != -1) return size;
    
          size = 0;
          if (id_ != 0) {
            size += com.google.protobuf.CodedOutputStream
              .computeInt32Size(1, id_);
          }
          if (!getNameBytes().isEmpty()) {
            size += com.google.protobuf.GeneratedMessageV3.computeStringSize(2, name_);
          }
          if (age_ != 0) {
            size += com.google.protobuf.CodedOutputStream
              .computeInt32Size(3, age_);
          }
          if (state_ != 0) {
            size += com.google.protobuf.CodedOutputStream
              .computeInt32Size(4, state_);
          }
          size += unknownFields.getSerializedSize();
          memoizedSize = size;
          return size;
        }
    
        @java.lang.Override
        public boolean equals(final java.lang.Object obj) {
          if (obj == this) {
           return true;
          }
          if (!(obj instanceof com.netty.protobuf.UserInfo.UserMsg)) {
            return super.equals(obj);
          }
          com.netty.protobuf.UserInfo.UserMsg other = (com.netty.protobuf.UserInfo.UserMsg) obj;
    
          if (getId()
              != other.getId()) return false;
          if (!getName()
              .equals(other.getName())) return false;
          if (getAge()
              != other.getAge()) return false;
          if (getState()
              != other.getState()) return false;
          if (!unknownFields.equals(other.unknownFields)) return false;
          return true;
        }
    
        @java.lang.Override
        public int hashCode() {
          if (memoizedHashCode != 0) {
            return memoizedHashCode;
          }
          int hash = 41;
          hash = (19 * hash) + getDescriptor().hashCode();
          hash = (37 * hash) + ID_FIELD_NUMBER;
          hash = (53 * hash) + getId();
          hash = (37 * hash) + NAME_FIELD_NUMBER;
          hash = (53 * hash) + getName().hashCode();
          hash = (37 * hash) + AGE_FIELD_NUMBER;
          hash = (53 * hash) + getAge();
          hash = (37 * hash) + STATE_FIELD_NUMBER;
          hash = (53 * hash) + getState();
          hash = (29 * hash) + unknownFields.hashCode();
          memoizedHashCode = hash;
          return hash;
        }
    
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            java.nio.ByteBuffer data)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            java.nio.ByteBuffer data,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data, extensionRegistry);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            com.google.protobuf.ByteString data)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            com.google.protobuf.ByteString data,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data, extensionRegistry);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(byte[] data)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            byte[] data,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws com.google.protobuf.InvalidProtocolBufferException {
          return PARSER.parseFrom(data, extensionRegistry);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(java.io.InputStream input)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseWithIOException(PARSER, input);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            java.io.InputStream input,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseWithIOException(PARSER, input, extensionRegistry);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseDelimitedFrom(java.io.InputStream input)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseDelimitedWithIOException(PARSER, input);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseDelimitedFrom(
            java.io.InputStream input,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseDelimitedWithIOException(PARSER, input, extensionRegistry);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            com.google.protobuf.CodedInputStream input)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseWithIOException(PARSER, input);
        }
        public static com.netty.protobuf.UserInfo.UserMsg parseFrom(
            com.google.protobuf.CodedInputStream input,
            com.google.protobuf.ExtensionRegistryLite extensionRegistry)
            throws java.io.IOException {
          return com.google.protobuf.GeneratedMessageV3
              .parseWithIOException(PARSER, input, extensionRegistry);
        }
    
        @java.lang.Override
        public Builder newBuilderForType() { return newBuilder(); }
        public static Builder newBuilder() {
          return DEFAULT_INSTANCE.toBuilder();
        }
        public static Builder newBuilder(com.netty.protobuf.UserInfo.UserMsg prototype) {
          return DEFAULT_INSTANCE.toBuilder().mergeFrom(prototype);
        }
        @java.lang.Override
        public Builder toBuilder() {
          return this == DEFAULT_INSTANCE
              ? new Builder() : new Builder().mergeFrom(this);
        }
    
        @java.lang.Override
        protected Builder newBuilderForType(
            com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
          Builder builder = new Builder(parent);
          return builder;
        }
        /**
         * Protobuf type {@code UserMsg}
         */
        public static final class Builder extends
            com.google.protobuf.GeneratedMessageV3.Builder<Builder> implements
            // @@protoc_insertion_point(builder_implements:UserMsg)
            com.netty.protobuf.UserInfo.UserMsgOrBuilder {
          public static final com.google.protobuf.Descriptors.Descriptor
              getDescriptor() {
            return com.netty.protobuf.UserInfo.internal_static_UserMsg_descriptor;
          }
    
          @java.lang.Override
          protected com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
              internalGetFieldAccessorTable() {
            return com.netty.protobuf.UserInfo.internal_static_UserMsg_fieldAccessorTable
                .ensureFieldAccessorsInitialized(
                    com.netty.protobuf.UserInfo.UserMsg.class, com.netty.protobuf.UserInfo.UserMsg.Builder.class);
          }
    
          // Construct using com.netty.protobuf.UserInfo.UserMsg.newBuilder()
          private Builder() {
            maybeForceBuilderInitialization();
          }
    
          private Builder(
              com.google.protobuf.GeneratedMessageV3.BuilderParent parent) {
            super(parent);
            maybeForceBuilderInitialization();
          }
          private void maybeForceBuilderInitialization() {
            if (com.google.protobuf.GeneratedMessageV3
                    .alwaysUseFieldBuilders) {
            }
          }
          @java.lang.Override
          public Builder clear() {
            super.clear();
            id_ = 0;
    
            name_ = "";
    
            age_ = 0;
    
            state_ = 0;
    
            return this;
          }
    
          @java.lang.Override
          public com.google.protobuf.Descriptors.Descriptor
              getDescriptorForType() {
            return com.netty.protobuf.UserInfo.internal_static_UserMsg_descriptor;
          }
    
          @java.lang.Override
          public com.netty.protobuf.UserInfo.UserMsg getDefaultInstanceForType() {
            return com.netty.protobuf.UserInfo.UserMsg.getDefaultInstance();
          }
    
          @java.lang.Override
          public com.netty.protobuf.UserInfo.UserMsg build() {
            com.netty.protobuf.UserInfo.UserMsg result = buildPartial();
            if (!result.isInitialized()) {
              throw newUninitializedMessageException(result);
            }
            return result;
          }
    
          @java.lang.Override
          public com.netty.protobuf.UserInfo.UserMsg buildPartial() {
            com.netty.protobuf.UserInfo.UserMsg result = new com.netty.protobuf.UserInfo.UserMsg(this);
            result.id_ = id_;
            result.name_ = name_;
            result.age_ = age_;
            result.state_ = state_;
            onBuilt();
            return result;
          }
    
          @java.lang.Override
          public Builder clone() {
            return super.clone();
          }
          @java.lang.Override
          public Builder setField(
              com.google.protobuf.Descriptors.FieldDescriptor field,
              java.lang.Object value) {
            return super.setField(field, value);
          }
          @java.lang.Override
          public Builder clearField(
              com.google.protobuf.Descriptors.FieldDescriptor field) {
            return super.clearField(field);
          }
          @java.lang.Override
          public Builder clearOneof(
              com.google.protobuf.Descriptors.OneofDescriptor oneof) {
            return super.clearOneof(oneof);
          }
          @java.lang.Override
          public Builder setRepeatedField(
              com.google.protobuf.Descriptors.FieldDescriptor field,
              int index, java.lang.Object value) {
            return super.setRepeatedField(field, index, value);
          }
          @java.lang.Override
          public Builder addRepeatedField(
              com.google.protobuf.Descriptors.FieldDescriptor field,
              java.lang.Object value) {
            return super.addRepeatedField(field, value);
          }
          @java.lang.Override
          public Builder mergeFrom(com.google.protobuf.Message other) {
            if (other instanceof com.netty.protobuf.UserInfo.UserMsg) {
              return mergeFrom((com.netty.protobuf.UserInfo.UserMsg)other);
            } else {
              super.mergeFrom(other);
              return this;
            }
          }
    
          public Builder mergeFrom(com.netty.protobuf.UserInfo.UserMsg other) {
            if (other == com.netty.protobuf.UserInfo.UserMsg.getDefaultInstance()) return this;
            if (other.getId() != 0) {
              setId(other.getId());
            }
            if (!other.getName().isEmpty()) {
              name_ = other.name_;
              onChanged();
            }
            if (other.getAge() != 0) {
              setAge(other.getAge());
            }
            if (other.getState() != 0) {
              setState(other.getState());
            }
            this.mergeUnknownFields(other.unknownFields);
            onChanged();
            return this;
          }
    
          @java.lang.Override
          public final boolean isInitialized() {
            return true;
          }
    
          @java.lang.Override
          public Builder mergeFrom(
              com.google.protobuf.CodedInputStream input,
              com.google.protobuf.ExtensionRegistryLite extensionRegistry)
              throws java.io.IOException {
            com.netty.protobuf.UserInfo.UserMsg parsedMessage = null;
            try {
              parsedMessage = PARSER.parsePartialFrom(input, extensionRegistry);
            } catch (com.google.protobuf.InvalidProtocolBufferException e) {
              parsedMessage = (com.netty.protobuf.UserInfo.UserMsg) e.getUnfinishedMessage();
              throw e.unwrapIOException();
            } finally {
              if (parsedMessage != null) {
                mergeFrom(parsedMessage);
              }
            }
            return this;
          }
    
          private int id_ ;
          /**
           * <code>int32 id = 1;</code>
           * @return The id.
           */
          @java.lang.Override
          public int getId() {
            return id_;
          }
          /**
           * <code>int32 id = 1;</code>
           * @param value The id to set.
           * @return This builder for chaining.
           */
          public Builder setId(int value) {
            
            id_ = value;
            onChanged();
            return this;
          }
          /**
           * <code>int32 id = 1;</code>
           * @return This builder for chaining.
           */
          public Builder clearId() {
            
            id_ = 0;
            onChanged();
            return this;
          }
    
          private java.lang.Object name_ = "";
          /**
           * <code>string name = 2;</code>
           * @return The name.
           */
          public java.lang.String getName() {
            java.lang.Object ref = name_;
            if (!(ref instanceof java.lang.String)) {
              com.google.protobuf.ByteString bs =
                  (com.google.protobuf.ByteString) ref;
              java.lang.String s = bs.toStringUtf8();
              name_ = s;
              return s;
            } else {
              return (java.lang.String) ref;
            }
          }
          /**
           * <code>string name = 2;</code>
           * @return The bytes for name.
           */
          public com.google.protobuf.ByteString
              getNameBytes() {
            java.lang.Object ref = name_;
            if (ref instanceof String) {
              com.google.protobuf.ByteString b = 
                  com.google.protobuf.ByteString.copyFromUtf8(
                      (java.lang.String) ref);
              name_ = b;
              return b;
            } else {
              return (com.google.protobuf.ByteString) ref;
            }
          }
          /**
           * <code>string name = 2;</code>
           * @param value The name to set.
           * @return This builder for chaining.
           */
          public Builder setName(
              java.lang.String value) {
            if (value == null) {
        throw new NullPointerException();
      }
      
            name_ = value;
            onChanged();
            return this;
          }
          /**
           * <code>string name = 2;</code>
           * @return This builder for chaining.
           */
          public Builder clearName() {
            
            name_ = getDefaultInstance().getName();
            onChanged();
            return this;
          }
          /**
           * <code>string name = 2;</code>
           * @param value The bytes for name to set.
           * @return This builder for chaining.
           */
          public Builder setNameBytes(
              com.google.protobuf.ByteString value) {
            if (value == null) {
        throw new NullPointerException();
      }
      checkByteStringIsUtf8(value);
            
            name_ = value;
            onChanged();
            return this;
          }
    
          private int age_ ;
          /**
           * <code>int32 age = 3;</code>
           * @return The age.
           */
          @java.lang.Override
          public int getAge() {
            return age_;
          }
          /**
           * <code>int32 age = 3;</code>
           * @param value The age to set.
           * @return This builder for chaining.
           */
          public Builder setAge(int value) {
            
            age_ = value;
            onChanged();
            return this;
          }
          /**
           * <code>int32 age = 3;</code>
           * @return This builder for chaining.
           */
          public Builder clearAge() {
            
            age_ = 0;
            onChanged();
            return this;
          }
    
          private int state_ ;
          /**
           * <code>int32 state = 4;</code>
           * @return The state.
           */
          @java.lang.Override
          public int getState() {
            return state_;
          }
          /**
           * <code>int32 state = 4;</code>
           * @param value The state to set.
           * @return This builder for chaining.
           */
          public Builder setState(int value) {
            
            state_ = value;
            onChanged();
            return this;
          }
          /**
           * <code>int32 state = 4;</code>
           * @return This builder for chaining.
           */
          public Builder clearState() {
            
            state_ = 0;
            onChanged();
            return this;
          }
          @java.lang.Override
          public final Builder setUnknownFields(
              final com.google.protobuf.UnknownFieldSet unknownFields) {
            return super.setUnknownFields(unknownFields);
          }
    
          @java.lang.Override
          public final Builder mergeUnknownFields(
              final com.google.protobuf.UnknownFieldSet unknownFields) {
            return super.mergeUnknownFields(unknownFields);
          }
    
    
          // @@protoc_insertion_point(builder_scope:UserMsg)
        }
    
        // @@protoc_insertion_point(class_scope:UserMsg)
        private static final com.netty.protobuf.UserInfo.UserMsg DEFAULT_INSTANCE;
        static {
          DEFAULT_INSTANCE = new com.netty.protobuf.UserInfo.UserMsg();
        }
    
        public static com.netty.protobuf.UserInfo.UserMsg getDefaultInstance() {
          return DEFAULT_INSTANCE;
        }
    
        private static final com.google.protobuf.Parser<UserMsg>
            PARSER = new com.google.protobuf.AbstractParser<UserMsg>() {
          @java.lang.Override
          public UserMsg parsePartialFrom(
              com.google.protobuf.CodedInputStream input,
              com.google.protobuf.ExtensionRegistryLite extensionRegistry)
              throws com.google.protobuf.InvalidProtocolBufferException {
            return new UserMsg(input, extensionRegistry);
          }
        };
    
        public static com.google.protobuf.Parser<UserMsg> parser() {
          return PARSER;
        }
    
        @java.lang.Override
        public com.google.protobuf.Parser<UserMsg> getParserForType() {
          return PARSER;
        }
    
        @java.lang.Override
        public com.netty.protobuf.UserInfo.UserMsg getDefaultInstanceForType() {
          return DEFAULT_INSTANCE;
        }
    
      }
    
      private static final com.google.protobuf.Descriptors.Descriptor
        internal_static_UserMsg_descriptor;
      private static final 
        com.google.protobuf.GeneratedMessageV3.FieldAccessorTable
          internal_static_UserMsg_fieldAccessorTable;
    
      public static com.google.protobuf.Descriptors.FileDescriptor
          getDescriptor() {
        return descriptor;
      }
      private static  com.google.protobuf.Descriptors.FileDescriptor
          descriptor;
      static {
        java.lang.String[] descriptorData = {
          "\n\nUser.proto\"?\n\007UserMsg\022\n\n\002id\030\001 \001(\005\022\014\n\004n" +
          "ame\030\002 \001(\t\022\013\n\003age\030\003 \001(\005\022\r\n\005state\030\004 \001(\005B\036\n" +
          "\022com.netty.protobufB\010UserInfob\006proto3"
        };
        descriptor = com.google.protobuf.Descriptors.FileDescriptor
          .internalBuildGeneratedFileFrom(descriptorData,
            new com.google.protobuf.Descriptors.FileDescriptor[] {
            });
        internal_static_UserMsg_descriptor =
          getDescriptor().getMessageTypes().get(0);
        internal_static_UserMsg_fieldAccessorTable = new
          com.google.protobuf.GeneratedMessageV3.FieldAccessorTable(
            internal_static_UserMsg_descriptor,
            new java.lang.String[] { "Id", "Name", "Age", "State", });
      }
    
      // @@protoc_insertion_point(outer_class_scope)
    }

## 效果截图: ##

服务端:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n_size_16_color_FFFFFF_t_70][]

客户端:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n_size_16_color_FFFFFF_t_70 1][]

补充：针对自定义协议实体对象。

Java 代码示例：

// 按照定义的数据结构，创建一个对象
    UserInfo.UserMsg.Builder userInfo = UserInfo.UserMsg.newBuilder();
    userInfo.setId(1);
    userInfo.setName("zhouchenxi");
    userInfo.setAge(2);
    UserInfo.UserMsg userMsg = userInfo.build();
    // 将数据写到输出流
    ByteArrayOutputStream output = new ByteArrayOutputStream();
    userMsg.writeTo(output);
    // 将数据序列化后发送
    byte[] byteArray = output.toByteArray();
    // 接收到流并读取
    ByteArrayInputStream input = new ByteArrayInputStream(byteArray);
    // 反序列化
    UserInfo.UserMsg userInfo2 = UserInfo.UserMsg.parseFrom(input);
    System.out.println("id:" + userInfo2.getId());
    System.out.println("name:" + userInfo2.getName());
    System.out.println("age:" + userInfo2.getAge());

[Netty _google ProtoBuf]: https://blog.csdn.net/zhouzhiwengang/article/details/112187715
[https_blog.csdn.net_kunfeisang5551_article_details_107957256]: https://blog.csdn.net/kunfeisang5551/article/details/107957256
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20210104180239624.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20210104180250822.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3pob3V6aGl3ZW5nYW5n,size_16,color_FFFFFF,t_70