第3讲编解码

本章要点：

java序列化缺点
业界流行的集中编解码框架介绍

3.1 java序列化缺点

无法跨越语言，是java序列化最致命的缺点；
序列化后的码流太大
序列化性能太低

3.2 主流编辑码框架

3.2.1 Google Protobuf编解码

Protobuf在业界非常流行，Protobuf具有以下有点：

产品成熟
跨语言、支持多种语言
编码后消息更小，便与存储和传输
编解码性能高、
支持定义可选和必选字段
Protobuf是一个灵活、高效、结构化的数据序列化框架，相比于XML等传统的序列化工具，它更小、更快、更简单。
https://github.com/google/protobuf/releases
下载protof工具，protoc-3.5.1-win32.zip，并解压，会看到protoc.exe工具。

User.proto的文件内容如下：

package com.bj58.wuxian.protobuf;

option java_outer_classname = "UserProto"; 
message User{
    required int32 id=1;
    required string username=2;
    required string password=3;
    enum Sex{
     nan=1;
     nv=2;
    }
    required Sex sex=4;
}

执行如下命令：

D:/develop/protoc-3.5.1-win32/bin/protoc.exe -I=./proto --java_out=D:/develop/protoc-3.5.1-win32/bin/proto/ ./proto/User.proto

生成了一个UserProto.java文件。
protoc.exe -I=proto的输入目录 --java_out=java类输出目录 proto的输入目录包括包括proto文件
此时将UserProto.java文件拷贝到IDE中会报错，那是因为缺少包依赖：

        <dependency>
            <groupId>com.google.protobuf</groupId>
            <artifactId>protobuf-java</artifactId>
            <version>3.5.1</version>
        </dependency>

protobuf序列化传输代码实例：
UserServer代码：

package com.bj58.wuxian.netty.codec.protobuf;

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;

import com.bj58.wuxian.protobuf.UserProto;

public class UserServer {
    
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup bossGroup=new NioEventLoopGroup(); 
        EventLoopGroup workGroup=new NioEventLoopGroup();
        try {
            ServerBootstrap bootstrap=new ServerBootstrap();
            bootstrap.group(bossGroup, workGroup)
            .channel(NioServerSocketChannel.class)
            .option(ChannelOption.SO_BACKLOG, 1024)
            .handler(new LoggingHandler(LogLevel.INFO))
            .childHandler(new ChannelInitializer<SocketChannel>() {

                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new ProtobufVarint32FrameDecoder());//用于半包处理
                    ch.pipeline().addLast(new ProtobufDecoder(UserProto.User.getDefaultInstance()));//ProtobufDecoder参数是所要解码的目标类
                    ch.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
                    ch.pipeline().addLast(new ProtobufEncoder());
                    ch.pipeline().addLast(new UserServerHandler());
                }
            });
            
            ChannelFuture f=bootstrap.bind(8888).sync();
            f.channel().closeFuture().sync();
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            bossGroup.shutdownGracefully();
            workGroup.shutdownGracefully();
        }
    }
}

UserServerHandler 代码：

package com.bj58.wuxian.netty.codec.protobuf;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import com.bj58.wuxian.protobuf.UserProto;
import com.bj58.wuxian.protobuf.UserProto.User.Sex;

public class UserServerHandler  extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("**********server channelActive*************");
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        
        UserProto.User user =(UserProto.User)msg;
        System.out.println("request:"+msg);
        UserProto.User.Builder builder = UserProto.User.newBuilder();
        builder.setId(123);
        builder.setSex(Sex.nv);
        builder.setPassword("45678");
        if("zhaoshichao".equalsIgnoreCase(user.getUsername())){
            builder.setUsername("shangjing");
        }else{
            builder.setUsername("guanggunhan");
        }
        UserProto.User wife = builder.build();
        ctx.writeAndFlush(wife);
    }

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

UserClient 代码：

package com.bj58.wuxian.netty.codec.protobuf;

import com.bj58.wuxian.protobuf.UserProto;

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 UserClient {
    public static void main(String[] args) throws InterruptedException {
        EventLoopGroup group=new NioEventLoopGroup();
        
        try {
            Bootstrap bootstrap=new Bootstrap();
            bootstrap.group(group)
            .channel(NioSocketChannel.class)
            .option(ChannelOption.TCP_NODELAY, true)
            .handler(new ChannelInitializer<SocketChannel>() {

                @Override
                protected void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(new ProtobufVarint32FrameDecoder());
                    ch.pipeline().addLast(new ProtobufDecoder(UserProto.User.getDefaultInstance()));
                    ch.pipeline().addLast(new ProtobufVarint32LengthFieldPrepender());
                    ch.pipeline().addLast(new ProtobufEncoder());
                    ch.pipeline().addLast(new UserClientHandler());
                }
            });
            
            ChannelFuture f=bootstrap.connect("127.0.0.1",8888).sync();
            f.channel().closeFuture().sync();
            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            group.shutdownGracefully();
        }
    }
}

UserClientHandler 代码：

package com.bj58.wuxian.netty.codec.protobuf;

import com.bj58.wuxian.protobuf.UserProto;
import com.bj58.wuxian.protobuf.UserProto.User.Sex;

import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class UserClientHandler extends ChannelInboundHandlerAdapter {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        for(int i=0;i<=5;i++){
            UserProto.User.Builder builder = UserProto.User.newBuilder();
            builder.setId(123);
            builder.setSex(Sex.nan);
            builder.setPassword("45678");
            if(i%2==0){
                builder.setUsername("zhaoshichao");
            }else{
                builder.setUsername("zhaoshichao"+i);
            }
            
            UserProto.User wife = builder.build();
            ctx.writeAndFlush(wife);
        }
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        System.out.println("response:"+(UserProto.User)msg);
    }

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

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }
}

3.2.1 Message Pack编解码

MessagePack特点如下：

编解码高效，性能高
序列化之后的码流小
支持跨语言

添加pom依赖：

        <dependency>
            <groupId>org.msgpack</groupId>
            <artifactId>msgpack</artifactId>
            <version>0.6.12</version>
        </dependency>

自定义编码器：

package com.bj58.wuxian.netty.codec.msgpack;

import org.msgpack.MessagePack;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToByteEncoder;

public class MsgPackEncoder extends MessageToByteEncoder<Object> {

    @Override
    protected void encode(ChannelHandlerContext ctx, Object msg, ByteBuf out)
            throws Exception {
        MessagePack msfPack=new MessagePack();
        byte[] bytes=msfPack.write(msg);
        out.writeBytes(bytes);
    }
}

自定义解码器：

package com.bj58.wuxian.netty.codec.msgpack;

import java.util.List;
import org.msgpack.MessagePack;
import com.bj58.wuxian.msgpack.model.User;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;

public class MsgPackDecoder extends MessageToMessageDecoder<ByteBuf> {

    @Override
    protected void decode(ChannelHandlerContext ctx, ByteBuf msg,
            List<Object> out) throws Exception {
        byte[] bytes=new byte[msg.readableBytes()];
        msg.readBytes(bytes);
        MessagePack messagePack=new MessagePack();
        out.add(messagePack.read(bytes,User.class));
    }
}

UserServer代码：

package com.bj58.wuxian.netty.codec.msgpack;

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.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;

public class UserServer {
    public static void main(String[] argsStrings) throws Exception {
        // 配置服务端NIO线程组(boss线程、worker线程)
        EventLoopGroup bGroup = new NioEventLoopGroup();
        EventLoopGroup wGroup = new NioEventLoopGroup();
        // 创建启动辅助类
        ServerBootstrap bootstrap = new ServerBootstrap();
        bootstrap.group(bGroup, wGroup).channel(NioServerSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
                .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000)
                .childHandler(new ChannelInitializer<SocketChannel>() {
                    @Override
                    protected void initChannel(SocketChannel channel) throws Exception {
                        // 添加对象系列化编解码器,同时提供粘包拆包支持
                        channel.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535, 0, 2, 0, 2));
                        channel.pipeline().addLast("解码器", new MsgPackDecoder());
                        channel.pipeline().addLast(new LengthFieldPrepender(2));
                        channel.pipeline().addLast("编码器", new MsgPackEncoder());
                        channel.pipeline().addLast(new UserServerHandler());
                    }

                });

        try {
            // 监听本地端口,同步等待监听结果
            ChannelFuture future = bootstrap.bind(8888).sync();
            // 等待服务端监听端口关闭,优雅退出
            future.channel().closeFuture().sync();
        } finally {
            bGroup.shutdownGracefully();
            wGroup.shutdownGracefully();
        }

    }
}

ServerHanler代码：

package com.bj58.wuxian.netty.codec.msgpack;

import com.bj58.wuxian.msgpack.model.User;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class UserServerHandler extends ChannelInboundHandlerAdapter  {

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        System.out.println("**********server channelActive**********");
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        User user=(User)msg;
        User wife=new User();
        if("zhaoshichao".equals(user.getUsername())){
            wife.setPassword("1234");
            wife.setUsername("shangjing");;
        }else{
            wife.setPassword("1234");
            wife.setUsername("others");
        }
        
        ctx.writeAndFlush(wife);
    }

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

}

User客户端：

package com.bj58.wuxian.netty.codec.msgpack;


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.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;

public class UserClient {
    public static void  main(String [] argsStrings) throws Exception {  
        //配置客户端端NIO线程组  
        EventLoopGroup bGroup = new NioEventLoopGroup();  
        //创建客户端启动辅助类  
        Bootstrap bootstrap = new Bootstrap();  
        bootstrap.group(bGroup).  
                  channel(NioSocketChannel.class).  
                  option(ChannelOption.TCP_NODELAY, true).  
                  option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 3000).  
                  handler(new ChannelInitializer<SocketChannel>() {  
                        @Override  
                        protected void initChannel(SocketChannel channel) throws Exception {  
                            //添加对象系列化编解码器,同时提供粘包拆包支持  
                            channel.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535, 0, 2, 0, 2));
                            channel.pipeline().addLast("解码器", new MsgPackDecoder());
                            channel.pipeline().addLast(new LengthFieldPrepender(2));
                            channel.pipeline().addLast("编码器", new MsgPackEncoder());
                            channel.pipeline().addLast(new UserClientHandler());
                        }  
                           
                    });  
          
        //发起异步连接  
        ChannelFuture future = bootstrap.connect("127.0.0.1", 8888).sync();  
        try {  
            //等待客户端链路关闭  
            future.channel().closeFuture().sync();  
            } finally {  
            //优雅退出,释放资源  
            bGroup.shutdownGracefully();  
        }  
    }  
}

ClientHandler代码：

package com.bj58.wuxian.netty.codec.msgpack;

import com.bj58.wuxian.msgpack.model.User;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

public class UserClientHandler extends ChannelInboundHandlerAdapter{
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        for(int i=0;i<=5;i++){
            User user=new User();
            user.setId(123);
            user.setPassword("45678");
            if(i%2==0){
                user.setUsername("zhaoshichao");
            }else{
                user.setUsername("zhaoshichao"+i);
            }
            
            ctx.writeAndFlush(user);
        }
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg)
            throws Exception {
        System.out.println("response:"+(User)msg);
    }

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

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        ctx.flush();
    }

}

最后编辑于：2018.05.08 22:24:20

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第3讲 编解码