Netty Google Protobuf

1.编码和解码的基本介绍 ：
1) 编写网络应用程序时， 因为数据在网络中传输的都是二进制字节码数据， 在发送数据时就需要编码， 接收数据时就需要解码 [示意图]
2) codec(编解码器) 的组成部分有两个： decoder(解码器)和 encoder(编码器)。 encoder 负责把业务数据转换成字节码数据， decoder 负责把字节码数据转换成业务数据 

---

 2.Netty 本身的编码解码的机制和问题分析

1) Netty 自身提供了一些 codec(编解码器)
2) Netty 提供的编码器
       StringEncoder， 对字符串数据进行编码
       ObjectEncoder， 对 Java 对象进行编码
       ...
3) Netty 提供的解码器
      StringDecoder, 对字符串数据进行解码
      ObjectDecoder， 对 Java 对象进行解码
      ...
4) Netty 本身自带的 ObjectDecoder 和 ObjectEncoder 可以用来实现 POJO 对象或各种业务对象的编码和解码， 底层使用的仍是 Java 序列化技术 ,

而 Java 序列化技术本身效率就不高， 存在如下问题无法跨语言序列化后的体积太大， 是二进制编码的 5 倍多。序列化性能太低 
5) => 引出 新的解决方案 [Google 的 Protobuf]

---

3.Protobuf
1) Protobuf 基本介绍和使用示意图

 2) Protobuf 是 Google 发布的开源项目， 全称 Google Protocol Buffers， 是一种轻便高效的结构化数据存储格式，可以用于结构化数据串行化，

    或者说序列化。 它很适合做数据存储或 RPC[远程过程调用 remote procedure call ] 数据交换格式 。目前很多公司 http+json tcp+protobuf 

3) 参考文档 : https://developers.google.com/protocol-buffers/docs/proto 语言指南
4) Protobuf 是以 message 的方式来管理数据的.
5) 支持跨平台、 跨语言， 即[客户端和服务器端可以是不同的语言编写的] （支持目前绝大多数语言， 例如 C++、C#、 Java、 python 等）
6) 高性能， 高可靠性
7) 使用 protobuf 编译器能自动生成代码， Protobuf 是将类的定义使用.proto 文件进行描述。 说明， 在 idea 中编写 .proto 文件时， 会自动提示是否下载 .ptotot 编写插件. 可以让语法高亮。
8) 然后通过 protoc.exe 编译器根据.proto 自动生成.java 文件

---

4 Protobuf 快速入门实例 

编写程序， 使用 Protobuf 完成如下功能
1) 客户端可以发送一个 Student PoJo 对象到服务器 (通过 Protobuf 编码)
2) 服务端能接收 Student PoJo 对象， 并显示信息(通过 Protobuf 解码)

Student.proto

syntax = "proto3"; //版本
option java_outer_classname = "StudentPOJO";//生成的外部类名， 同时也是文件名
//protobuf 使用 message 管理数据
message Student { //会在 StudentPOJO 外部类生成一个内部类 Student， 他是真正发送的 POJO 对象
int32 id = 1; // Student 类中有 一个属性 名字为 id 类型为 int32(protobuf 类型) 1 表示属性序号， 不是值
string name = 2;
}

编译
protoc.exe --java_out=. Student.proto
将生成的 StudentPOJO 放入到项目使用

NettyClient

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelPipeline;
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.ProtobufEncoder;

public class NettyClient {
    public static void main(String[] args) throws Exception {

        //客户端需要一个事件循环组
        EventLoopGroup group = new NioEventLoopGroup();


        try {
            //创建客户端启动对象
            //注意客户端使用的不是 ServerBootstrap 而是 Bootstrap
            Bootstrap bootstrap = new Bootstrap();

            //设置相关参数
            bootstrap.group(group) //设置线程组
                    .channel(NioSocketChannel.class) // 设置客户端通道的实现类(反射)
                    .handler(new ChannelInitializer<SocketChannel>() {
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {
                            ChannelPipeline pipeline = ch.pipeline();
                            //在pipeline中加入 ProtoBufEncoder
                            pipeline.addLast("encoder", new ProtobufEncoder());
                            pipeline.addLast(new NettyClientHandler()); //加入自己的处理器
                        }
                    });

            System.out.println("客户端 ok..");

            //启动客户端去连接服务器端
            //关于 ChannelFuture 要分析，涉及到netty的异步模型
            ChannelFuture channelFuture = bootstrap.connect("127.0.0.1", 6668).sync();
            //给关闭通道进行监听
            channelFuture.channel().closeFuture().sync();
        }finally {

            group.shutdownGracefully();

        }
    }
}

NettyClientHandler

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

public class NettyClientHandler extends ChannelInboundHandlerAdapter {

    //当通道就绪就会触发该方法
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        //发生一个Student 对象到服务器

        StudentPOJO.Student student = StudentPOJO.Student.newBuilder().setId(4).setName("智多星 吴用").build();
        //Teacher , Member ,Message
        ctx.writeAndFlush(student);
    }

    //当通道有读取事件时，会触发
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        ByteBuf buf = (ByteBuf) msg;
        System.out.println("服务器回复的消息:" + buf.toString(CharsetUtil.UTF_8));
        System.out.println("服务器的地址： "+ ctx.channel().remoteAddress());
    }

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

NettyServer

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.codec.protobuf.ProtobufDecoder;

public class NettyServer {
    public static void main(String[] args) throws Exception {


        //创建BossGroup 和 WorkerGroup
        //说明
        //1. 创建两个线程组 bossGroup 和 workerGroup
        //2. bossGroup 只是处理连接请求 , 真正的和客户端业务处理，会交给 workerGroup完成
        //3. 两个都是无限循环
        //4. bossGroup 和 workerGroup 含有的子线程(NioEventLoop)的个数
        //   默认实际 cpu核数 * 2
        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
        EventLoopGroup workerGroup = new NioEventLoopGroup(); //8



        try {
            //创建服务器端的启动对象，配置参数
            ServerBootstrap bootstrap = new ServerBootstrap();

            //使用链式编程来进行设置
            bootstrap.group(bossGroup, workerGroup) //设置两个线程组
                    .channel(NioServerSocketChannel.class) //使用NioSocketChannel 作为服务器的通道实现
                    .option(ChannelOption.SO_BACKLOG, 128) // 设置线程队列得到连接个数
                    .childOption(ChannelOption.SO_KEEPALIVE, true) //设置保持活动连接状态
//                    .handler(null) // 该 handler对应 bossGroup , childHandler 对应 workerGroup
                    .childHandler(new ChannelInitializer<SocketChannel>() {//创建一个通道初始化对象(匿名对象)
                        //给pipeline 设置处理器
                        @Override
                        protected void initChannel(SocketChannel ch) throws Exception {


                            ChannelPipeline pipeline = ch.pipeline();
                            //在pipeline加入ProtoBufDecoder
                            //指定对哪种对象进行解码
                            pipeline.addLast("decoder", new ProtobufDecoder(StudentPOJO.Student.getDefaultInstance()));
                            pipeline.addLast(new NettyServerHandler());
                        }
                    }); // 给我们的workerGroup 的 EventLoop 对应的管道设置处理器

            System.out.println(".....服务器 is ready...");

            //绑定一个端口并且同步, 生成了一个 ChannelFuture 对象
            //启动服务器(并绑定端口)
            ChannelFuture cf = bootstrap.bind(6668).sync();

            //给cf 注册监听器，监控我们关心的事件

            cf.addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture future) throws Exception {
                    if (cf.isSuccess()) {
                        System.out.println("监听端口 6668 成功");
                    } else {
                        System.out.println("监听端口 6668 失败");
                    }
                }
            });


            //对关闭通道进行监听
            cf.channel().closeFuture().sync();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }

}

NettyServerHandler

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.util.CharsetUtil;

/*
说明
1. 我们自定义一个Handler 需要继续netty 规定好的某个HandlerAdapter(规范)
2. 这时我们自定义一个Handler , 才能称为一个handler
 */
//public class NettyServerHandler extends ChannelInboundHandlerAdapter {
public class NettyServerHandler extends SimpleChannelInboundHandler<StudentPOJO.Student> {


    //读取数据实际(这里我们可以读取客户端发送的消息)
    /*
    1. ChannelHandlerContext ctx:上下文对象, 含有 管道pipeline , 通道channel, 地址
    2. Object msg: 就是客户端发送的数据 默认Object
     */
    @Override
    public void channelRead0(ChannelHandlerContext ctx, StudentPOJO.Student msg) throws Exception {

        //读取从客户端发送的StudentPojo.Student


        System.out.println("客户端发送的数据 id=" + msg.getId() + " 名字=" + msg.getName());
    }



//    //读取数据实际(这里我们可以读取客户端发送的消息)
//    /*
//    1. ChannelHandlerContext ctx:上下文对象, 含有 管道pipeline , 通道channel, 地址
//    2. Object msg: 就是客户端发送的数据 默认Object
//     */
//    @Override
//    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
//
//        //读取从客户端发送的StudentPojo.Student
//
//        StudentPOJO.Student student = (StudentPOJO.Student) msg;
//
//        System.out.println("客户端发送的数据 id=" + student.getId() + " 名字=" + student.getName());
//    }

    //数据读取完毕
    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {

        //writeAndFlush 是 write + flush
        //将数据写入到缓存，并刷新
        //一般讲，我们对这个发送的数据进行编码
        ctx.writeAndFlush(Unpooled.copiedBuffer("hello, 客户端~(>^ω^<)喵1", CharsetUtil.UTF_8));
    }

    //处理异常, 一般是需要关闭通道

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

生成的 StudentPOJO

public final class StudentPOJO {
  private StudentPOJO() {}
  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 StudentOrBuilder extends
      // @@protoc_insertion_point(interface_extends:Student)
      com.google.protobuf.MessageOrBuilder {

    /**
     * <pre>
     * Student 类中有 一个属性 名字为 id 类型为int32(protobuf类型) 1表示属性序号，不是值
     * </pre>
     *
     * <code>int32 id = 1;</code>
     */
    int getId();

    /**
     * <code>string name = 2;</code>
     */
    String getName();
    /**
     * <code>string name = 2;</code>
     */
    com.google.protobuf.ByteString
        getNameBytes();
  }
  /**
   * <pre>
   *protobuf 使用message 管理数据
   * </pre>
   *
   * Protobuf type {@code Student}
   */
  public  static final class Student extends
      com.google.protobuf.GeneratedMessageV3 implements
      // @@protoc_insertion_point(message_implements:Student)
      StudentOrBuilder {
  private static final long serialVersionUID = 0L;
    // Use Student.newBuilder() to construct.
    private Student(com.google.protobuf.GeneratedMessageV3.Builder<?> builder) {
      super(builder);
    }
    private Student() {
      id_ = 0;
      name_ = "";
    }

    @Override
    public final com.google.protobuf.UnknownFieldSet
    getUnknownFields() {
      return this.unknownFields;
    }
    private Student(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      this();
      if (extensionRegistry == null) {
        throw new NullPointerException();
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      try {
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            case 8: {

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              break;
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              String s = input.readStringRequireUtf8();

              name_ = s;
              break;
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            default: {
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        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 StudentPOJO.internal_static_Student_descriptor;
    }

    @Override
    protected FieldAccessorTable
        internalGetFieldAccessorTable() {
      return StudentPOJO.internal_static_Student_fieldAccessorTable
          .ensureFieldAccessorsInitialized(
              Student.class, Builder.class);
    }

    public static final int ID_FIELD_NUMBER = 1;
    private int id_;
    /**
     * <pre>
     * Student 类中有 一个属性 名字为 id 类型为int32(protobuf类型) 1表示属性序号，不是值
     * </pre>
     *
     * <code>int32 id = 1;</code>
     */
    public int getId() {
      return id_;
    }

    public static final int NAME_FIELD_NUMBER = 2;
    private volatile Object name_;
    /**
     * <code>string name = 2;</code>
     */
    public String getName() {
      Object ref = name_;
      if (ref instanceof String) {
        return (String) ref;
      } else {
        com.google.protobuf.ByteString bs = 
            (com.google.protobuf.ByteString) ref;
        String s = bs.toStringUtf8();
        name_ = s;
        return s;
      }
    }
    /**
     * <code>string name = 2;</code>
     */
    public com.google.protobuf.ByteString
        getNameBytes() {
      Object ref = name_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b = 
            com.google.protobuf.ByteString.copyFromUtf8(
                (String) ref);
        name_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
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    private byte memoizedIsInitialized = -1;
    @Override
    public final boolean isInitialized() {
      byte isInitialized = memoizedIsInitialized;
      if (isInitialized == 1) return true;
      if (isInitialized == 0) return false;

      memoizedIsInitialized = 1;
      return true;
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    @Override
    public void writeTo(com.google.protobuf.CodedOutputStream output)
                        throws java.io.IOException {
      if (id_ != 0) {
        output.writeInt32(1, id_);
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      if (!getNameBytes().isEmpty()) {
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      unknownFields.writeTo(output);
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    @Override
    public int getSerializedSize() {
      int size = memoizedSize;
      if (size != -1) return size;

      size = 0;
      if (id_ != 0) {
        size += com.google.protobuf.CodedOutputStream
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    }

    @Override
    public boolean equals(final Object obj) {
      if (obj == this) {
       return true;
      }
      if (!(obj instanceof Student)) {
        return super.equals(obj);
      }
      Student other = (Student) obj;

      boolean result = true;
      result = result && (getId()
          == other.getId());
      result = result && getName()
          .equals(other.getName());
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    @Override
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      int hash = 41;
      hash = (19 * hash) + getDescriptor().hashCode();
      hash = (37 * hash) + ID_FIELD_NUMBER;
      hash = (53 * hash) + getId();
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      hash = (53 * hash) + getName().hashCode();
      hash = (29 * hash) + unknownFields.hashCode();
      memoizedHashCode = hash;
      return hash;
    }

    public static Student parseFrom(
        java.nio.ByteBuffer data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static Student parseFrom(
        java.nio.ByteBuffer data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static Student parseFrom(
        com.google.protobuf.ByteString data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static Student parseFrom(
        com.google.protobuf.ByteString data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static Student parseFrom(byte[] data)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data);
    }
    public static Student parseFrom(
        byte[] data,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws com.google.protobuf.InvalidProtocolBufferException {
      return PARSER.parseFrom(data, extensionRegistry);
    }
    public static Student parseFrom(java.io.InputStream input)
        throws java.io.IOException {
      return com.google.protobuf.GeneratedMessageV3
          .parseWithIOException(PARSER, input);
    }
    public static Student 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 Student parseDelimitedFrom(java.io.InputStream input)
        throws java.io.IOException {
      return com.google.protobuf.GeneratedMessageV3
          .parseDelimitedWithIOException(PARSER, input);
    }
    public static Student 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 Student parseFrom(
        com.google.protobuf.CodedInputStream input)
        throws java.io.IOException {
      return com.google.protobuf.GeneratedMessageV3
          .parseWithIOException(PARSER, input);
    }
    public static Student parseFrom(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      return com.google.protobuf.GeneratedMessageV3
          .parseWithIOException(PARSER, input, extensionRegistry);
    }

    @Override
    public Builder newBuilderForType() { return newBuilder(); }
    public static Builder newBuilder() {
      return DEFAULT_INSTANCE.toBuilder();
    }
    public static Builder newBuilder(Student prototype) {
      return DEFAULT_INSTANCE.toBuilder().mergeFrom(prototype);
    }
    @Override
    public Builder toBuilder() {
      return this == DEFAULT_INSTANCE
          ? new Builder() : new Builder().mergeFrom(this);
    }

    @Override
    protected Builder newBuilderForType(
        BuilderParent parent) {
      Builder builder = new Builder(parent);
      return builder;
    }
    /**
     * <pre>
     *protobuf 使用message 管理数据
     * </pre>
     *
     * Protobuf type {@code Student}
     */
    public static final class Builder extends
        com.google.protobuf.GeneratedMessageV3.Builder<Builder> implements
        // @@protoc_insertion_point(builder_implements:Student)
        StudentOrBuilder {
      public static final com.google.protobuf.Descriptors.Descriptor
          getDescriptor() {
        return StudentPOJO.internal_static_Student_descriptor;
      }

      @Override
      protected FieldAccessorTable
          internalGetFieldAccessorTable() {
        return StudentPOJO.internal_static_Student_fieldAccessorTable
            .ensureFieldAccessorsInitialized(
                Student.class, Builder.class);
      }

      // Construct using StudentPOJO.Student.newBuilder()
      private Builder() {
        maybeForceBuilderInitialization();
      }

      private Builder(
          BuilderParent parent) {
        super(parent);
        maybeForceBuilderInitialization();
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        return Student.getDefaultInstance();
      }

      @Override
      public Student build() {
        Student result = buildPartial();
        if (!result.isInitialized()) {
          throw newUninitializedMessageException(result);
        }
        return result;
      }

      @Override
      public Student buildPartial() {
        Student result = new Student(this);
        result.id_ = id_;
        result.name_ = name_;
        onBuilt();
        return result;
      }

      @Override
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          com.google.protobuf.Descriptors.FieldDescriptor field,
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          com.google.protobuf.Descriptors.FieldDescriptor field,
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      @Override
      public Builder mergeFrom(com.google.protobuf.Message other) {
        if (other instanceof Student) {
          return mergeFrom((Student)other);
        } else {
          super.mergeFrom(other);
          return this;
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      public Builder mergeFrom(Student other) {
        if (other == Student.getDefaultInstance()) return this;
        if (other.getId() != 0) {
          setId(other.getId());
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      private int id_ ;
      /**
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      }
      /**
       * <pre>
       * Student 类中有 一个属性 名字为 id 类型为int32(protobuf类型) 1表示属性序号，不是值
       * </pre>
       *
       * <code>int32 id = 1;</code>
       */
      public Builder setId(int value) {
        
        id_ = value;
        onChanged();
        return this;
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      /**
       * <pre>
       * Student 类中有 一个属性 名字为 id 类型为int32(protobuf类型) 1表示属性序号，不是值
       * </pre>
       *
       * <code>int32 id = 1;</code>
       */
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        id_ = 0;
        onChanged();
        return this;
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      // @@protoc_insertion_point(builder_scope:Student)
    }

    // @@protoc_insertion_point(class_scope:Student)
    private static final Student DEFAULT_INSTANCE;
    static {
      DEFAULT_INSTANCE = new Student();
    }

    public static Student getDefaultInstance() {
      return DEFAULT_INSTANCE;
    }

    private static final com.google.protobuf.Parser<Student>
        PARSER = new com.google.protobuf.AbstractParser<Student>() {
      @Override
      public Student parsePartialFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws com.google.protobuf.InvalidProtocolBufferException {
        return new Student(input, extensionRegistry);
      }
    };

    public static com.google.protobuf.Parser<Student> parser() {
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    }

    @Override
    public com.google.protobuf.Parser<Student> getParserForType() {
      return PARSER;
    }

    @Override
    public Student getDefaultInstanceForType() {
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    }

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  // @@protoc_insertion_point(outer_class_scope)
}