Msgpack序列化



Msgpack是一个基于二进制高效的对象序列化Library用于跨语言通信。它可以像JSON那样,在许多种语言之间交换结构对象;但是它比JSON更快速也更轻巧。 支持Python、Ruby、Java、C/C++、Javascript等众多语言。
由于某个POJO对象里含有Map类型的成员,在使用msgpack进行序列化和反序列化时,出现了一些奇怪的现象,比如反序列化出来的Map在进行get时无法表现出正常的操作,虽然Debug时看到内存里确实有数据。后来简单分析了一下发现,在没有指定模板类型时,msgpack反序列化出来的Map实际上是其Jar包内自己封装的一个Map实现类,所以就会出现上述的情况,要解决这个问题,就需要在反序列化解析时,给msgpack明确指定模板类型。

msgpack的内置提供了很多模板,其中就有MapTemplate,这是一个泛型类,在构造时需要指定key和val的模板类型,而msgpack并没有内置Object的模板,所以当如果需要序列化和反序列化一个Value是Object的Map时,就会出现问题。因此我们需要自己来实现一个Object的模板,代码如下:
public class ObjectTemplate extends AbstractTemplate {

private ObjectTemplate() {
}

static public ObjectTemplate getInstance() {
    return instance;
}

static final ObjectTemplate instance = new ObjectTemplate();

@Override
public void write(Packer pk, Object v, boolean required) throws IOException {
    if (v == null) {
        if (required) {
            throw new MessageTypeException("Attempted to write null");
        }
        pk.writeNil();
        return;
    }
    pk.write(v);
}

@Override
public Object read(Unpacker u, Object to, boolean required) throws IOException {
    if (!required && u.trySkipNil()) {
        return null;
    }

    return toObject(u.readValue());
}

private static Object toObject(Value value) throws IOException {
    Converter conv = new Converter(value);
    if (value.isNilValue()) { // null
        return null;
    } else if (value.isRawValue()) { // byte[] or String or maybe Date?
        // deserialize value to String object
        RawValue v = value.asRawValue();
        return conv.read(Templates.TString);
    } else if (value.isBooleanValue()) { // boolean
        return conv.read(Templates.TBoolean);
    } else if (value.isIntegerValue()) { // int or long or BigInteger
        // deserialize value to int
        IntegerValue v = value.asIntegerValue();
        return conv.read(Templates.TInteger);
    } else if (value.isFloatValue()) { // float or double
        // deserialize value to double
        FloatValue v = value.asFloatValue();
        return conv.read(Templates.TDouble);
    } else if (value.isArrayValue()) { // List or Set
        // deserialize value to List object
        ArrayValue v = value.asArrayValue();
        List ret = new ArrayList(v.size());
        for (Value elementValue : v) {
            ret.add(toObject(elementValue));
        }
        return ret;
    } else if (value.isMapValue()) { // Map
        MapValue v = value.asMapValue();


        Map map = new HashMap<>(v.size());
        for (Map.Entry entry : v.entrySet()) {
            Value key = entry.getKey();
            Value val = entry.getValue();

            map.put(toObject(key), toObject(val));
        }

        return map;
    } else {
        throw new RuntimeException("fatal error");
    }
}
}
 

netty中使用msgpack序列化实例

服务端代码:

package cc.zychen.com;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;


public class EchoServer {

 public void bind(int port) throws Exception {
  EventLoopGroup bossGroup = new NioEventLoopGroup();
  EventLoopGroup workerGroup = new NioEventLoopGroup();
  try{
  ServerBootstrap b = new ServerBootstrap();
  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 ch) throws Exception {
    // TODO Auto-generated method stub
    ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535,0,4,0,4));
    ch.pipeline().addLast(new MsgPackDecoder());
    ch.pipeline().addLast(new LengthFieldPrepender(4,false));
    ch.pipeline().addLast(new MsgPackEncoder());
    ch.pipeline().addLast(new EchoServerHandler());
   }


  });
  
  //bind port
  ChannelFuture f = b.bind(port).sync();
  //wait
  f.channel().closeFuture().sync();
  }finally{
   bossGroup.shutdownGracefully();
   workerGroup.shutdownGracefully();
  }
 }
 /**
  * @param args
  */
 public static void main(String[] args) {
  int port = 8080;
  try {
   if(args != null && args.length > 0){
    port = Integer.parseInt(args[0]);
   }
   new EchoServer().bind(port);
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }

 }

}


package cc.zychen.com;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.msgpack.MessagePack;
import org.msgpack.template.Template;
import org.msgpack.template.Templates;
import org.msgpack.type.ArrayValue;
import org.msgpack.type.Value;

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

public class EchoServerHandler extends ChannelInboundHandlerAdapter {
 private int counter = 0;

 @Override
 public void channelRead(ChannelHandlerContext ctx, Object msg)
   throws Exception {
  
  @SuppressWarnings("unchecked")
  List u = (List)msg;
  System.out.println(u);
  
  @SuppressWarnings("deprecation")
  UserInfo t = MessagePack.unpack(MessagePack.pack(msg), UserInfo.class);
  System.out.println("this is "+ ++ counter +" times receive client:name[" + t.getName() +"]" +" age["+ t.getAge() +"]");
 
  UserInfo usInfo = new UserInfo();
  usInfo.setName("bbbbbbbbbb");
  usInfo.setAge(89);
  ctx.writeAndFlush(usInfo);
 }

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

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

}


package cc.zychen.com;

import java.util.List;

import org.msgpack.MessagePack;
import org.msgpack.template.Templates;
import org.msgpack.type.Value;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;

public class MsgPackDecoder extends MessageToMessageDecoder {

 @Override
 protected void decode(ChannelHandlerContext arg0, ByteBuf arg1,
   List arg2) throws Exception {
  final byte[] array;
  int length = arg1.readableBytes();
  array = new byte[length];
  arg1.getBytes(arg1.readerIndex(),array,0,length);
  MessagePack mpPack = new MessagePack();
  Value v = mpPack.read(array,Templates.TValue);
  arg2.add(v);
 }

}


package cc.zychen.com;

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 {

 @Override
 protected void encode(ChannelHandlerContext arg0, Object obj, ByteBuf buf)
   throws Exception {
  //序列化
  MessagePack mpPack = new MessagePack();
  byte [] raw = mpPack.write(obj);
  buf.writeBytes(raw);
 }
}


package cc.zychen.com;

import org.msgpack.annotation.Message;

@Message
public class UserInfo {
 protected String name;
 protected int age;
 
public String getName() {
 return name;
}
public void setName(String name) {
 this.name = name;
}
public int getAge() {
 return age;
}
public void setAge(int age) {
 this.age = age;
}
 
}

客户端代码:

package cc.zychen.com;

import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
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.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.string.StringDecoder;

public class EchoClient {

 public void connect(String ip,int port) throws InterruptedException{
  EventLoopGroup group = new NioEventLoopGroup();
  try{
  Bootstrap b = new Bootstrap();
  b.group(group)
  //.option(ChannelOption.TCP_NODELAY, true)
  .channel(NioSocketChannel.class)
  .handler(new ChannelInitializer() {

   @Override
   protected void initChannel(SocketChannel ch) throws Exception {
    ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535,0,4,0,4));
    ch.pipeline().addLast(new MsgPackDecoder());
    ch.pipeline().addLast(new LengthFieldPrepender(4,false));
    ch.pipeline().addLast(new MsgPackEncoder());
    ch.pipeline().addLast(new EchoClientHandler());
   }
  });
  
  ChannelFuture f = b.connect(ip, port).sync();
  f.channel().closeFuture().sync();
  } finally{
   group.shutdownGracefully();
  }
 }
 
 /**
  * @param args
  */
 public static void main(String[] args) {
  int port = 8080;
  try {
   if(args != null && args.length > 0){
    port = Integer.parseInt(args[0]);
   }
   new EchoClient().connect("127.0.0.1", port);
  } catch (Exception e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
 }
}


package cc.zychen.com;


import java.io.ByteArrayInputStream;
import java.util.List;

import org.msgpack.MessagePack;
import org.msgpack.template.TemplateRegistry;
import org.msgpack.template.Templates;
import org.msgpack.type.Value;

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

public class EchoClientHandler extends ChannelInboundHandlerAdapter {
 private int counter = 0;
 @Override
 public void channelRead(ChannelHandlerContext ctx, Object msg)
   throws Exception {
  
  @SuppressWarnings("unchecked")
  List u = (List)msg;
  System.out.println(u);

  //@SuppressWarnings("deprecation")
  UserInfo t = MessagePack.unpack(MessagePack.pack(msg),UserInfo.class);
  System.out.println("this is "+ ++ counter +" times receive server:name[" + t.getName() +"]" +" age["+ t.getAge() +"]");
 }

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

 @Override
 public void channelActive(ChannelHandlerContext ctx) throws Exception {
  UserInfo usInfo = null;
  for(int n=0;n<10;n++){
   usInfo = new UserInfo();
   usInfo.setName("aaaaaaa");
   usInfo.setAge(88);
   ctx.write(usInfo);
  }
  ctx.flush();
 }

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

}


package cc.zychen.com;

import java.util.List;

import org.msgpack.MessagePack;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.MessageToMessageDecoder;

public class MsgPackDecoder extends MessageToMessageDecoder {

 @Override
 protected void decode(ChannelHandlerContext arg0, ByteBuf arg1,
   List arg2) throws Exception {
  final byte[] array;
  int length = arg1.readableBytes();
  array = new byte[length];
  arg1.getBytes(arg1.readerIndex(),array,0,length);
  MessagePack mpPack = new MessagePack();
  arg2.add(mpPack.read(array));
 }

}


package cc.zychen.com;

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 {

 @Override
 protected void encode(ChannelHandlerContext arg0, Object arg1, ByteBuf arg2)
   throws Exception {
  //序列化
  MessagePack mpPack = new MessagePack();
  byte [] raw = mpPack.write(arg1);
  arg2.writeBytes(raw);
 }
}


package cc.zychen.com;

import org.msgpack.annotation.Message;

@Message
public class UserInfo {
 protected String name;
 protected int age;
 
public String getName() {
 return name;
}
public void setName(String name) {
 this.name = name;
}
public int getAge() {
 return age;
}
public void setAge(int age) {
 this.age = age;
}
 
}

完整代码下载:http://download.csdn.net/download/byxdaz/10141725

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