Netty入门教程：Netty拆包粘包技术讲解

Netty编解码技术是什么意思呢？所谓的编解码技术，说白了就是java序列化技术。序列化有两个目的：

1、进行网络传输
2、对象持久化

虽然我们可以使用java进行序列化，Netty去传输。但是java序列化的硬伤太多，比如java的序列化无法跨平台、序列化后码流太大、序列化性能非常低等等...

码流太大是什么意思呢？比如说原先的我一篇文档，比如说大小是1M，序列化完了之后可能0.5M，序列化减少二分之一的码，比较大。然后0.5M去网络传输这个不太好。你比如说用其它的一些主流序列化的话可能就0.01M，非常小。性能非常好。

性能太低就是说，我用java序列化的过程可能需要10s，而用其它的高性能序列化可能0.1s。差距就是这么的大。

序列化的目的无非就是网络传输。而目前主流的序列化框架有以下几种：

1、JBoss的Marshalling
2、Google的Protobuf
3、基于Protobuf的Kyro
4、MessagePack框架

其实我们主要是讲Marshalling和Google的Protobuf。这两个是业界非常好用的框架。其中JBoss的Marshalling速度还要比Google的Protobuf要快，原因是因为Marshalling不是跨语言，两端都是java与java之间相互传输的。因此，在这种情况下我们就用它就行了。但如果你想实现跨语言，比如这边是c#，另一边是java。这种跨语言进行通信传输的话，那你就需要用到Google的Protobuf来进行跨语言的传输。性能也非常高。而且它自己有一些大端小端的优化机制。

下面开始Marshalling编码实现。

首先新建一个java工程，导入netty和jboss-marshalling的jar包，导入几张图片到sources文件夹以便测试。

新建一个Req类，并编写相关代码

 package com.it448.serial;

 import java.io.Serializable;

 public class Req implements Serializable{
     private static final long serialVersionUID = 1L;

     private String id ;
     private String name ;
     private String requestMessage ;
     private byte[] attachment;

     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getRequestMessage() {
         return requestMessage;
     }
     public void setRequestMessage(String requestMessage) {
         this.requestMessage = requestMessage;
     }
     public byte[] getAttachment() {
         return attachment;
     }
     public void setAttachment(byte[] attachment) {
         this.attachment = attachment;
     }
 }

新建一个Resp类，并编写相关代码

 package com.it448.serial;

 import java.io.Serializable;

 public class Resp implements Serializable{

     private static final long serialVersionUID = 1L;

     private String id;
     private String name;
     private String responseMessage;

     public String getId() {
         return id;
     }
     public void setId(String id) {
         this.id = id;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getResponseMessage() {
         return responseMessage;
     }
     public void setResponseMessage(String responseMessage) {
         this.responseMessage = responseMessage;
     }
 }

新建一个工具类GzipUtils，方便调用

 package com.it448.utils;

 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.util.zip.GZIPInputStream;
 import java.util.zip.GZIPOutputStream;

 public class GzipUtils {
     public static byte[] gzip(byte[] data) throws Exception{
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         GZIPOutputStream gzip = new GZIPOutputStream(bos);
         gzip.write(data);
         gzip.finish();
         gzip.close();
         byte[] ret = bos.toByteArray();
         bos.close();
         return ret;
     }

     public static byte[] ungzip(byte[] data) throws Exception{
         ByteArrayInputStream bis = new ByteArrayInputStream(data);
         GZIPInputStream gzip = new GZIPInputStream(bis);
         byte[] buf = new byte[1024];
         int num = -1;
         ByteArrayOutputStream bos = new ByteArrayOutputStream();
         while((num = gzip.read(buf, 0 , buf.length)) != -1 ){
             bos.write(buf, 0, num);
         }
         gzip.close();
         bis.close();
         byte[] ret = bos.toByteArray();
         bos.flush();
         bos.close();
         return ret;
     }

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

         // 读取文件
         String readPath = System.getProperty("user.dir") + File.separatorChar + "sources" +  File.separatorChar + "006.jpg";
         File file = new File(readPath);
         FileInputStream in = new FileInputStream(file);
         byte[] data = new byte[in.available()];
         in.read(data);
         in.close();  

         System.out.println("文件原始大小:" + data.length);
         // 测试压缩

         byte[] ret1 = GzipUtils.gzip(data);
         System.out.println("压缩之后大小:" + ret1.length);

         byte[] ret2 = GzipUtils.ungzip(ret1);
         System.out.println("还原之后大小:" + ret2.length);

         // 写出文件
         String writePath = System.getProperty("user.dir") + File.separatorChar + "receive" +  File.separatorChar + "006.jpg";
         FileOutputStream fos = new FileOutputStream(writePath);
         fos.write(ret2);
         fos.close();
     }
 }

新建一个Marshalling工厂类MarshallingCodeCFactory.java

 package com.it448.serial;

 import io.netty.handler.codec.marshalling.DefaultMarshallerProvider;
 import io.netty.handler.codec.marshalling.DefaultUnmarshallerProvider;
 import io.netty.handler.codec.marshalling.MarshallerProvider;
 import io.netty.handler.codec.marshalling.MarshallingDecoder;
 import io.netty.handler.codec.marshalling.MarshallingEncoder;
 import io.netty.handler.codec.marshalling.UnmarshallerProvider;

 import org.jboss.marshalling.MarshallerFactory;
 import org.jboss.marshalling.Marshalling;
 import org.jboss.marshalling.MarshallingConfiguration;

 /**
  * Marshalling工厂
  * @author（xyh）
  * @since 2019-06-12
  */
 public final class MarshallingCodeCFactory {

     /**
           * 创建Jboss Marshalling解码器MarshallingDecoder
      * @return MarshallingDecoder
      */
     public static MarshallingDecoder buildMarshallingDecoder() {
         // 首先通过Marshalling工具类的精通方法获取Marshalling实例对象 参数serial标识创建的是java序列化工厂对象。
         final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
         // 创建了MarshallingConfiguration对象，配置了版本号为5
         final MarshallingConfiguration configuration = new MarshallingConfiguration();
         configuration.setVersion(5);
         // 根据marshallerFactory和configuration创建provider
         UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
         // 构建Netty的MarshallingDecoder对象，俩个参数分别为provider和单个消息序列化后的最大长度
         MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024 * 1024 * 1);
         return decoder;
     }

     /**
           * 创建Jboss Marshalling编码器MarshallingEncoder
      * @return MarshallingEncoder
      */
     public static MarshallingEncoder buildMarshallingEncoder() {
         final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
         final MarshallingConfiguration configuration = new MarshallingConfiguration();
         configuration.setVersion(5);
         MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
         // 构建Netty的MarshallingEncoder对象，MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
         MarshallingEncoder encoder = new MarshallingEncoder(provider);
         return encoder;
     }
 }

新建一个服务端的Handler类ServerHandler.java

 package com.it448.serial;

 import java.io.File;
 import java.io.FileOutputStream;

 import com.it448.utils.GzipUtils;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;

 public class ServerHandler extends ChannelInboundHandlerAdapter{
     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {
     }

     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
         Req req = (Req)msg;
         System.out.println("Server : " + req.getId() + ", " + req.getName() + ", " + req.getRequestMessage());
         byte[] attachment = GzipUtils.ungzip(req.getAttachment());

         String path = System.getProperty("user.dir") + File.separatorChar + "receive" +  File.separatorChar + "001.jpg";
         FileOutputStream fos = new FileOutputStream(path);
         fos.write(attachment);
         fos.close();

         Resp resp = new Resp();
         resp.setId(req.getId());
         resp.setName("resp" + req.getId());
         resp.setResponseMessage("响应内容" + req.getId());
         ctx.writeAndFlush(resp);
     }

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

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

新建一个服务端类Server.java

 package com.it448.serial;

 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.logging.LogLevel;
 import io.netty.handler.logging.LoggingHandler;

 public class Server {
     public static void main(String[] args) throws Exception{
         EventLoopGroup pGroup = new NioEventLoopGroup();
         EventLoopGroup cGroup = new NioEventLoopGroup();

         ServerBootstrap b = new ServerBootstrap();
         b.group(pGroup, cGroup)
          .channel(NioServerSocketChannel.class)
          .option(ChannelOption.SO_BACKLOG, 1024)
          // 设置日志
          .handler(new LoggingHandler(LogLevel.INFO))
          .childHandler(new ChannelInitializer<SocketChannel>() {
             protected void initChannel(SocketChannel sc) throws Exception {
                 sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
                 sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
                 sc.pipeline().addLast(new ServerHandler());
             }
         });

         ChannelFuture cf = b.bind(8765).sync();

         cf.channel().closeFuture().sync();
         pGroup.shutdownGracefully();
         cGroup.shutdownGracefully();
     }
 }

新建一个客户端Handler类ClientHandler.java

 package com.it448.serial;

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

 public class ClientHandler extends ChannelInboundHandlerAdapter{
     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {
     }

     @Override
     public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
         try {
             Resp resp = (Resp)msg;
             System.out.println("Client : " + resp.getId() + ", " + resp.getName() + ", " + resp.getResponseMessage());
         } finally {
             ReferenceCountUtil.release(msg);
         }
     }

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

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

新建一个客户端类Client.java

 package com.it448.serial;

 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 java.io.File;
 import java.io.FileInputStream;

 import com.it448.utils.GzipUtils;

 public class Client {
     public static void main(String[] args) throws Exception{
         EventLoopGroup group = new NioEventLoopGroup();
         Bootstrap b = new Bootstrap();
         b.group(group)
          .channel(NioSocketChannel.class)
          .handler(new ChannelInitializer<SocketChannel>() {
             @Override
             protected void initChannel(SocketChannel sc) throws Exception {
                 sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
                 sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
                 sc.pipeline().addLast(new ClientHandler());
             }
         });

         ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();

         for(int i = 0; i < 1000; i++ ){
             Req req = new Req();
             req.setId("" + i);
             req.setName("pro" + i);
             req.setRequestMessage("数据信息" + i);
             String path = System.getProperty("user.dir") + File.separatorChar + "sources" +  File.separatorChar + "001.jpg";
             File file = new File(path);
             FileInputStream in = new FileInputStream(file);
             byte[] data = new byte[in.available()];
             in.read(data);
             in.close();
             req.setAttachment(GzipUtils.gzip(data));
             cf.channel().writeAndFlush(req);
         }

         cf.channel().closeFuture().sync();
         group.shutdownGracefully();
     }
 }

代码测试

首先启动服务端，也就是运行Server类的main方法。

然后启用客户端，也就是运行Client类的main方法。

测试结果

从图中可以看到，receive文件夹多了一张001.jpg的图片。说明图片已经传输过来了。

好了，这部分内容就讲到这里，送上今天的福利：三套Netty系列教程【价值600】，加wxhaox就可以领取。当然了，对应netty有任何疑问也都可以咨询！！

end -- 1560313059

　　-- 学而不思则罔，思而不学则殆