Netty结合Protobuf进行编解码的方法

 一般在使用netty时,数据传输的时候都会选择对传输的数据进行编解码,编码后的数据变小, 有利于在有限的带宽下传输更多的数据。

由于java本身序列化的缺点较多(无法跨语言,序列化后的码流太大,序列化的性能太低等),业界主流的编解码框架主要有如下三个:

  1. Google的Protobuf
  2. Facebook的Thrift
  3. JBoss的Marshalling

今天我们简单介绍一下Netty结合google的Protobuf框架进行数据的编解码。

1. 什么是Protobuf?

Protobuf全称是Google Protocol Buffers, 它是谷歌公司开源的一个序列化框架。

它将数据结构以.proto文件进行描述,通过代码生成工具可以生成对应数据结构的POJO对象和Protobuf相关的方法和属性。

它的特点如下:

  1. 结构化数据存储格式
  2. 高效的编解码性能
  3. 语言无关、平台无关、扩展性好
  4. 官方支持多个语言(java,c++,python,c#等)

2. 下载安装

Protobuf已经托管在github上,可以在release页面下载,本案例使用的是v3.6(要下载后缀为-win32.zip的)。

下载后,将压缩包进行解压。这里主要用到bin目录下的protoc.exe。

3. 定义好proto文件

SubscribeReq.proto

// 区分不同的protobuf版本,必须有
syntax = "proto2";
 
package netty;
// 生成的目标类的包路径
option java_package = "cn.ddlover.nettystudy.protobuf";
// 生成的目标类的名字
option java_outer_classname = "SubscribeReqProto";
 
message SubscribeReq{
    required int32 subReqID = 1;
    required string userName = 2;
    required string productName = 3;
    repeated string address = 4;
}

SubscribeResp.proto

syntax = "proto2";
package netty;
 
option java_package = "cn.ddlover.nettystudy.protobuf";
option java_outer_classname = "SubscribeRespProto";
 
message SubscribeResp{
    required int32 subReqID = 1;
    required int32 respCode = 2;
    required string desc = 3;
}

此时项目结构如下

Netty结合Protobuf进行编解码的方法_第1张图片

重点关注一下两个proto文件的位置,是位于项目的根路径下

4. 分别执行以下命令

D:\xhb\protoc-3.6.1-win32\bin\protoc.exe --java_out=.\src\main\java SubscribeResp.proto 

D:\xhb\protoc-3.6.1-win32\bin\protoc.exe --java_out=.\src\main\java SubscribeReq.proto 

这里需要把protoc.exe的位置换成自己的, --java_out命令设置的是proto文件中java_package指令的父目录。

5. 此时项目结构如下

Netty结合Protobuf进行编解码的方法_第2张图片

下面开始代码方面的开发,

1. 先贴一波maven的配置



    4.0.0
 
    cn.ddlover
    nettystudy
    1.0-SNAPSHOT
 
 
    
        1.8
    
 
    
        
        
            io.netty
            netty-all
            4.1.33.Final
        
        
        
            com.google.protobuf
            protobuf-java
            3.6.1
        
 
        
            org.projectlombok
            lombok
            1.18.4
        
    

2. 这里贴上完整代码的项目结构

Netty结合Protobuf进行编解码的方法_第3张图片

3. SubReqServer.java

 
import cn.ddlover.nettystudy.handler.SubReqServerHandler;
import cn.ddlover.nettystudy.protobuf.SubscribeReqProto;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
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;
 
/**
 * Protobuf版本图书订购代码
 */
public class SubReqServer {
    private static final int PORT = 8080;
 
    public static void main(String[] args) {
        bind(PORT);
    }
 
    private static void bind(int port) {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();
 
        ServerBootstrap b = new ServerBootstrap();
        try {
            b.group(bossGroup, workerGroup)
                    .channel(NioServerSocketChannel.class)
                    .option(ChannelOption.SO_BACKLOG, 100)
                    .handler(new LoggingHandler(LogLevel.INFO))
                    .childHandler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
                            // 半包处理
                            socketChannel.pipeline().addLast(new ProtobufVarint32FrameDecoder());
                            socketChannel.pipeline().addLast(new ProtobufDecoder(SubscribeReqProto.SubscribeReq.getDefaultInstance()));
                            socketChannel.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
                            socketChannel.pipeline().addLast(new ProtobufEncoder());
                            socketChannel.pipeline().addLast(new SubReqServerHandler());
                        }
                    });
            ChannelFuture future = b.bind(port).sync();
            future.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }
    }
}

4. SubReqServerHandler.java

import cn.ddlover.nettystudy.protobuf.SubscribeReqProto;
import cn.ddlover.nettystudy.protobuf.SubscribeRespProto;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
 
public class SubReqServerHandler extends ChannelInboundHandlerAdapter {
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        SubscribeReqProto.SubscribeReq req = (SubscribeReqProto.SubscribeReq)msg;
 
        if ("张三".equals(req.getUserName())) {
            System.out.println("Server accept clietn subscribe req : ["+req.toString()+"]");
            ctx.writeAndFlush(resp(req.getSubReqID()));
        }
    }
 
    private SubscribeRespProto.SubscribeResp resp(int subReqID) {
        SubscribeRespProto.SubscribeResp.Builder builder = SubscribeRespProto.SubscribeResp.newBuilder();
        builder.setSubReqID(subReqID);
        builder.setRespCode(0);
        builder.setDesc("netty书籍下单成功,3天后将会送到你的住处");
        return builder. build();
    }
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

5. SubReqClient.java

import cn.ddlover.nettystudy.handler.SubReqClientHandler;
import cn.ddlover.nettystudy.protobuf.SubscribeRespProto;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
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 SubReqClient {
    private static final String HOST = "localhost";
    private static final int PORT = 8080;
 
    public static void main(String[] args) {
        connect(HOST, PORT);
    }
 
    private static void connect(String host, int port) {
        EventLoopGroup group = new NioEventLoopGroup();
 
        Bootstrap b = new Bootstrap();
        try {
            b.group(group).channel(NioSocketChannel.class)
                    .option(ChannelOption.TCP_NODELAY, true)
                    .handler(new ChannelInitializer() {
                        @Override
                        protected void initChannel(SocketChannel socketChannel) throws Exception {
 
                            // 半包处理
                            socketChannel.pipeline().addLast(new ProtobufVarint32FrameDecoder());
                            socketChannel.pipeline().addLast(new ProtobufDecoder(SubscribeRespProto.SubscribeResp.getDefaultInstance()));
                            socketChannel.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
                            socketChannel.pipeline().addLast(new ProtobufEncoder());
                            socketChannel.pipeline().addLast(new SubReqClientHandler());
                        }
                    });
            ChannelFuture f = b.connect(host, port).sync();
            f.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            group.shutdownGracefully();
        }
    }
}

6. SubReqClientHandler.java

import cn.ddlover.nettystudy.protobuf.SubscribeReqProto;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
 
import java.util.ArrayList;
import java.util.List;
 
public class SubReqClientHandler extends ChannelInboundHandlerAdapter {
 
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        for (int i =0;i<10;i++) {
            ctx.write(subReq(i));
        }
        ctx.flush();
    }
 
    private SubscribeReqProto.SubscribeReq subReq(int i) {
        SubscribeReqProto.SubscribeReq.Builder builder = SubscribeReqProto.SubscribeReq.newBuilder();
        builder.setSubReqID(i);
        builder.setUserName("张三");
        builder.setProductName("Netty Book");
        List address = new ArrayList<>();
        address.add("NanJing YuHuaTai");
        address.add("BeiJing LiuLiChang");
        address.add("ShenZhen HongShuLin");
        builder.addAllAddress(address);
        return builder.build();
    }
 
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        System.out.println("Receive server response : ["+ msg +"]");
    }
 
 
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        cause.printStackTrace();
        ctx.close();
    }
}

代码部分到此就结束了,然后分别运行SubReqServerSubReqClient, 就可以发现运行成功了。

这里要注意的事,调用toString的时候,中文在控制台打印的是字节,而调用对应属性的getter方法的时候,是可以做中文的判断的,显然这里protobuf的toString没有被修改好呀。

当然,我们也可以发现,netty本身已经封装好了对谷歌的protobuf的支持。Netty还是很强大的。

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