MessagePack 序列化框架的简单实现。
1.导入相关jar包
如果使用maven的话，直接添加依赖即可：
0.6.12
org.msgpack
msgpack
${msgpack.version}
如果是普通java项目，去[maven中央仓库](https://search.maven.org/#search%7Cga%7C1%7Cg%3A%22ch.dissem.msgpack%22)下载即可
2.编写Encoder(编码器)
继承MessageToByteEncoder
public class MsgpackEncoder extends MessageToByteEncoder {
@Override
protected void encode(ChannelHandlerContext ctx, Object msg, ByteBuf out) throws Exception {
// TODO Auto-generated method stub
MessagePack msgpack = new MessagePack();
out.writeBytes(msgpack.write(msg));
}
}
3.编写Decoder(编码器)
继承MessageToMessageDecoder，设置类型为ByteBuf
public class MsgpackDecoder extends MessageToMessageDecoder {
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf msg, List 4.在Client端和Server端增加编码器和解码器，顺便增加粘包/拆包支持：
客户端代码：
public class NettyClient {
private void bind(int port,String host){
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group).channel(NioSocketChannel.class)
.option(ChannelOption.TCP_NODELAY, true).handler(new ClientHandlerInit());
try {
ChannelFuture f = b.connect(host, port).sync();
f.channel().closeFuture().sync();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
group.shutdownGracefully();
}
}
/*
*这里是增加相应的解码编码器。
*/
private class ClientHandlerInit extends ChannelInitializer{
@Override
protected void initChannel(SocketChannel ch) throws Exception {
// TODO Auto-generated method stub
//这里设置通过增加包头表示报文长度来避免粘包
ch.pipeline().addLast("frameDecoder",new LengthFieldBasedFrameDecoder(1024, 0, 2,0,2));
//增加解码器
ch.pipeline().addLast("msgpack decoder",new MsgpackDecoder());
//这里设置读取报文的包头长度来避免粘包
ch.pipeline().addLast("frameEncoder",new LengthFieldPrepender(2));
//增加编码器
ch.pipeline().addLast("msgpack encoder",new MsgpackEncoder());
ch.pipeline().addLast(new ClientHandler());
}
}
public static void main(String[] args) throws UnknownHostException {
// TODO Auto-generated method stub
NettyClient client = new NettyClient();
client.bind(12580,"localhost");
}
}
Server端代码，和client端大同小异，不再赘述
public class TimeServer {
public void bind(int port) throws Exception {
EventLoopGroup bossGruop = new NioEventLoopGroup();
EventLoopGroup workGroup = new NioEventLoopGroup();
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGruop, workGroup).channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024).childHandler(new ChildChannelHandler());
try {
ChannelFuture future = bootstrap.bind(port).sync();
future.channel().closeFuture().sync();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
bossGruop.shutdownGracefully();
workGroup.shutdownGracefully();
}
}
private class ChildChannelHandler extends ChannelInitializer {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
// TODO Auto-generated method stub
ch.pipeline().addLast("frameDecoder",new LengthFieldBasedFrameDecoder(1024, 0, 2,0,2));
ch.pipeline().addLast("msgpack decoder",new MsgpackDecoder());
ch.pipeline().addLast("frameEncoder",new LengthFieldPrepender(2));
ch.pipeline().addLast("msgpack encoder",new MsgpackEncoder());
ch.pipeline().addLast(new TimeServerHandler());
}
}
public static void main(String[] args) {
int port = 12580;
try {
new TimeServer().bind(port);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
5.接下来自定义一个model类来实作为消息类：
/*
*这里出现了两个坑，一个是需要在消息类上加上注解Message，另一个就是必须要有默认的无参构造器，不然就会报如下的错误：
*org.msgpack.template.builder.BuildContext build
*SEVERE: builder: 这个问题在github上有个issue解释了
*/
@Message
public class UserInfo {
private String username;
private String age;
public String getUsername() {
return username;
}
public String getAge() {
return age;
}
public void setUsername(String username) {
this.username = username;
}
public void setAge(String age) {
this.age = age;
}
public UserInfo(String username, String age) {
super();
this.username = username;
this.age = age;
}
public UserInfo(){
}
}
github关于错误的issue
6.对应的ServerHandler和ClientHandler代码：
serverhandler：
public class TimeServerHandler extends ChannelHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// TODO Auto-generated method stub
try {
//直接输出msg
System.out.println(msg.toString());
String remsg = new String("has receive");
//回复has receive 给客户端
ctx.write(remsg);
} catch (Exception e) {
e.printStackTrace();
}finally {
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
// TODO Auto-generated method stub
ctx.flush();
}
}
clientHanlder：
public class ClientHandler extends ChannelHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
// TODO Auto-generated method stub
System.out.println(msg);
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
// TODO Auto-generated method stub
//发送50个UserInfo给服务器，由于启用了粘包/拆包支持，所以这里连续发送多个也不会出现粘包的现象。
for (int i = 0; i < 50; i++) {
UserInfo userInfo = new UserInfo();
userInfo.setAge(i + "year");
userInfo.setUsername("senninha");
ctx.write(userInfo);
}
ctx.flush();
System.out.println("-----------------send over-----------------");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
// TODO Auto-generated method stub
System.out.println("error");
}
}
客户端控制台：
-----------------send over-----------------
"has receive"
"has receive"
"has receive"
"has receive"
"has receive"
"has receive"
........
服务器控制台：
["senninha","0year"]
["senninha","1year"]
["senninha","2year"]
["senninha","3year"]
["senninha","4year"]
["senninha","5year"]
["senninha","6year"]
至此，一个MessagePack序列化框架的入门就搭建好了，参考了《Netty权威指南》。