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<Integer, Object>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<Object> {
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<Object> ret = new ArrayList<Object>(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<Value, Value> 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<SocketChannel>() {
@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<Value> u = (List<Value>)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<ByteBuf> {
@Override
protected void decode(ChannelHandlerContext arg0, ByteBuf arg1,
List<Object> 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<Object> {
@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<SocketChannel>() {
@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<UserInfo> u = (List<UserInfo>)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<ByteBuf> {
@Override
protected void decode(ChannelHandlerContext arg0, ByteBuf arg1,
List<Object> 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<Object> {
@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;
}
}