普通TCP客户端和；使用Java的Netty服务器

我正在尝试使用Java中的Protobuf消息交换格式在普通TCP客户机和Netty服务器之间创建TCP套接字连接，但它不起作用。当我使用Netty客户端（而不是TCP客户端）和Netty服务器时，它就可以工作了

在Netty服务器端，在ServerHandler类中，我得到对象“msg”作为类型“PooledUnsafeDirectByteBuf”。现在，当我尝试将其转换为我的自定义Protobuf对象时，它失败了，错误为“java.lang.ClassCastException:class io.netty.buffer.PooledUnsafeDirectByteBuf无法转换为class ProtoModel”

public class ServerHandler extends ChannelInboundHandlerAdapter  {
---
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
--- 

客户端代码

Socket clientConnection = new Socket("localhost",SERVER_PORT);
ObjectOutputStream outToServer = new ObjectOutputStream(clientConnection.getOutputStream());
ProtoModel.writeTo(outToServer); //ProtoModel is the protobuf class

我认为这与TCP客户端的Protobuf消息编码和Netty服务器端的解码有关。当我使用Netty客户端（与普通TCP客户端相反）时，相同的服务器代码也可以工作

净客户代码

EventLoopGroup group = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group).channel(NioSocketChannel.class).handler(new ClientInitializer());
Channel ch = bootstrap.connect("localhost",SERVER_PORT).sync().channel();
ChannelFuture lastWriteFuture = ch.writeAndFlush(ProtoModel);
lastWriteFuture.channel().closeFuture().sync();

public void channelRead(ChannelHandlerContext ctx, Object msg) {
            ByteBuf buf = (ByteBuf) msg;
            byte[] req = new byte[buf.readableBytes()];
            buf.readBytes(req);
            ProtobufModel obj = ProtobufModel.parseFrom(ByteString.copyFrom(req));
}

SocketChannel channel = SocketChannel
                    .open(new InetSocketAddress(InetAddress.getByName("localhost"), SERVER_PORT));
          ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
          byteBuffer.put(ProtobufModel.toByteArray());
          byteBuffer.flip();
          channel.write(byteBuffer);

---

请让我知道，如果任何其他输入需要从我的结束。非常感谢。

我能够解决这个问题。我在下面发布解决方案

服务器代码

EventLoopGroup group = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group).channel(NioSocketChannel.class).handler(new ClientInitializer());
Channel ch = bootstrap.connect("localhost",SERVER_PORT).sync().channel();
ChannelFuture lastWriteFuture = ch.writeAndFlush(ProtoModel);
lastWriteFuture.channel().closeFuture().sync();

public void channelRead(ChannelHandlerContext ctx, Object msg) {
            ByteBuf buf = (ByteBuf) msg;
            byte[] req = new byte[buf.readableBytes()];
            buf.readBytes(req);
            ProtobufModel obj = ProtobufModel.parseFrom(ByteString.copyFrom(req));
}

SocketChannel channel = SocketChannel
                    .open(new InetSocketAddress(InetAddress.getByName("localhost"), SERVER_PORT));
          ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
          byteBuffer.put(ProtobufModel.toByteArray());
          byteBuffer.flip();
          channel.write(byteBuffer);

对象“msg”在服务器端以ByteBuf格式接收。然后需要将“ByteBuf”格式转换为“ByteString”，最后可以从“ByteString”格式检索ProtobufModel

客户端代码

EventLoopGroup group = new NioEventLoopGroup();
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(group).channel(NioSocketChannel.class).handler(new ClientInitializer());
Channel ch = bootstrap.connect("localhost",SERVER_PORT).sync().channel();
ChannelFuture lastWriteFuture = ch.writeAndFlush(ProtoModel);
lastWriteFuture.channel().closeFuture().sync();

public void channelRead(ChannelHandlerContext ctx, Object msg) {
            ByteBuf buf = (ByteBuf) msg;
            byte[] req = new byte[buf.readableBytes()];
            buf.readBytes(req);
            ProtobufModel obj = ProtobufModel.parseFrom(ByteString.copyFrom(req));
}

SocketChannel channel = SocketChannel
                    .open(new InetSocketAddress(InetAddress.getByName("localhost"), SERVER_PORT));
          ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
          byteBuffer.put(ProtobufModel.toByteArray());
          byteBuffer.flip();
          channel.write(byteBuffer);

在客户端，ProtobufModel转换为ByteBuffer并传递给服务器