JDK序列化不需要额外的类库，只需要实现Serializable即可，但是序列化之后的码流只有Java才能反序列化，所以它不是跨语言的，另外由于Java序列化后码流比较大，效率也不高，所以在RPC中很少使用，本文只是做学习之用。
编解码器：
public class JdkDecoder extends MessageToMessageDecoder<ByteBuf> { ???@Override ???protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception { ???????final int length = byteBuf.readableBytes(); ???????final byte[] b = new byte[length]; ???????byteBuf.getBytes(byteBuf.readerIndex(), b, 0, length); ???????ByteArrayInputStream bis = new ByteArrayInputStream(b); ???????ObjectInputStream ois = new ObjectInputStream(bis); ???????list.add(ois.readObject()); ???????ois.close(); ???}}public class JdkEncoder extends MessageToByteEncoder<Object> { ???@Override ???protected void encode(ChannelHandlerContext channelHandlerContext, Object o, ByteBuf byteBuf) throws Exception { ???????ByteArrayOutputStream bos = new ByteArrayOutputStream(); ???????ObjectOutputStream oos = new ObjectOutputStream(bos); ???????oos.writeObject(o); ???????oos.flush(); ???????byteBuf.writeBytes(bos.toByteArray()); ???????bos.close(); ???????oos.close(); ???}}---
传输对象：
public class Person implements Serializable{ ???private int age; ???private String name; ???private boolean man; ???private List<String> list; ???private Date birth; ???private Person son; ???public int getAge() { ???????return age; ???} ???public void setAge(int age) { ???????this.age = age; ???} ???。。。 ???@Override ???public String toString() { ???????return "Person{" + ???????????????"age=" + age + ???????????????", name=‘" + name + ‘\‘‘ + ???????????????", man=" + man + ???????????????", list=" + list + ???????????????", birth=" + birth + ???????????????", son=" + son + ???????????????‘}‘; ???}}---
Server端：
public class EchoServer { ???public static void main(String[] args) { ???????new EchoServer().bind(8080); ???} ???public void bind(int port) { ???????//配置服务端的线程组，一个用于服务端接收客户端连接，另一个进行SocketChannel的网络读写 ???????EventLoopGroup bossGroup = new NioEventLoopGroup(); ???????EventLoopGroup workerGroup = new NioEventLoopGroup(); ???????try { ???????????//ServerBootstrap用于启动NIO服务端的辅助启动类 ???????????ServerBootstrap bootstrap = new ServerBootstrap(); ???????????bootstrap.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 { ???????????????????????????// ???????????????????????????ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535, 0, 2, 0, 2)); ???????????????????????????//ch.pipeline().addLast(new MsgpackDecoder()); ???????????????????????????ch.pipeline().addLast(new JdkDecoder()); ???????????????????????????//在报文前增加2个字节，写消息长度 ???????????????????????????ch.pipeline().addLast(new LengthFieldPrepender(2)); ???????????????????????????//ch.pipeline().addLast(new MsgpackEncoder()); ???????????????????????????ch.pipeline().addLast(new JdkEncoder()); ???????????????????????????ch.pipeline().addLast(new EchoServerHandler()); ???????????????????????} ???????????????????}); ???????????//绑定端口，sync为同步阻塞方法，等待绑定成功,ChannelFuture用于异步操作的通知回调 ???????????ChannelFuture future = bootstrap.bind(port).sync(); ???????????System.out.println("server started"); ???????????//等待服务端监听端口关闭 ???????????future.channel().closeFuture().sync(); ???????} catch (InterruptedException e) { ???????????e.printStackTrace(); ???????} finally { ???????????System.out.println("server shuting down"); ???????????//释放线程资源 ???????????bossGroup.shutdownGracefully(); ???????????workerGroup.shutdownGracefully(); ???????} ???}}public class EchoServerHandler extends ChannelInboundHandlerAdapter { ???int count = 0; ???@Override ???public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { ???????if(msg instanceof Person){ ???????????Person p = (Person)msg; ???????????Q.p(p.toString()); ???????}else { ???????????System.out.println("The server received(" + count++ + "): " + msg); ???????} ???????ctx.writeAndFlush(msg);//异步发送 ???} ???@Override ???public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ???????cause.printStackTrace(); ???????ctx.close(); ???}}---
Client端：
public class EchoClient { ???public static void main(String[] args) { ???????new EchoClient().connect("127.0.0.1", 8080); ???} ???public void connect(String host, int port) { ???????//配置客户端NIO线程组 ???????EventLoopGroup group = new NioEventLoopGroup(); ???????try { ???????????Bootstrap bootstrap = new Bootstrap(); ???????????bootstrap.group(group).channel(NioSocketChannel.class) ???????????????????.option(ChannelOption.TCP_NODELAY, true) ???????????????????.handler(new ChannelInitializer<SocketChannel>() { ???????????????????????protected void initChannel(SocketChannel ch) throws Exception { ???????????????????????????ch.pipeline().addLast(new LengthFieldBasedFrameDecoder(65535, 0, 2, 0, 2)); ???????????????????????????//ch.pipeline().addLast(new MsgpackDecoder()); ???????????????????????????ch.pipeline().addLast(new JdkDecoder()); ???????????????????????????ch.pipeline().addLast(new LengthFieldPrepender(2)); ???????????????????????????//ch.pipeline().addLast(new MsgpackEncoder()); ???????????????????????????ch.pipeline().addLast(new JdkEncoder()); ???????????????????????????ch.pipeline().addLast(new EchoClientHandler()); ???????????????????????} ???????????????????}); ???????????//发起异步连接操作，同步等待连接成功 ???????????ChannelFuture future = bootstrap.connect(host, port).sync(); ???????????System.out.println("client started"); ???????????//等待客户端链路关闭 ???????????future.channel().closeFuture().sync(); ???????} catch (InterruptedException e) { ???????????e.printStackTrace(); ???????} finally { ???????????System.out.println("client shuting down"); ???????????//释放NIO线程组 ???????????group.shutdownGracefully(); ???????} ???}}public class EchoClientHandler extends ChannelInboundHandlerAdapter { ???private int count = 0; ???@Override ???public void channelActive(ChannelHandlerContext ctx) throws Exception { ???????List l = new ArrayList<String>(); ???????l.add("abc"); ???????l.add("123"); ???????Person p = new Person(); ???????p.setName("luangeng"); ???????p.setMan(true); ???????p.setBirth(new Date()); ???????p.setList(l); ???????for (int i = 0; i < 10; i++) { ???????????p.setAge(i); ???????????ctx.write(p); ???????} ???????ctx.flush(); ???} ???//服务端返回应答信息后调用 ???@Override ???public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { ???????if(msg instanceof Person){ ???????????Person p = (Person)msg; ???????????Q.p(p.toString()); ???????}else { ???????????Q.p(count++ + " client get: " + msg); ???????} ???} ???@Override ???public void channelReadComplete(ChannelHandlerContext ctx) throws Exception { ???????ctx.flush(); ???} ???@Override ???public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { ???????cause.printStackTrace(); ???????ctx.close(); ???}}---
执行结果：
client started
Person{age=0, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=1, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=2, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=3, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=4, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=5, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=6, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=7, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=8, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
Person{age=9, name=‘luangeng‘, man=true, list=[abc, 123], birth=Wed Nov 22 21:18:48 CST 2017, son=null}
MessagePack工具：
MessagePack是与JSON数据格式类似的二进制序列化格式，更快更小，并且是跨语言的，用于在多个语言之间交换数据。使用MessagePack实现的编解码器如下：
public class MsgpackEncoder extends MessageToByteEncoder<Object> { ???@Override ???protected void encode(ChannelHandlerContext channelHandlerContext, Object o, ByteBuf byteBuf) throws Exception { ???????MessagePack mp = new MessagePack(); ???????byte[] raw = mp.write(o); ???????byteBuf.writeBytes(raw); ???}}public class MsgpackDecoder extends MessageToMessageDecoder<ByteBuf> { ???@Override ???protected void decode(ChannelHandlerContext channelHandlerContext, ByteBuf byteBuf, List<Object> list) throws Exception { ???????final int length = byteBuf.readableBytes(); ???????final byte[] b = new byte[length]; ???????byteBuf.getBytes(byteBuf.readerIndex(), b, 0, length); ???????MessagePack mp = new MessagePack(); ???????list.add(mp.read(b)); ???}}---
使用这种编解码后，服务端和客户端接收到的对象都不能转换为Person对象。
end
Netty JDK序列化编解码传输对象
原文地址：http://www.cnblogs.com/luangeng/p/7881428.html