[网络协议]netty的ByteBuf转字节输入流InputStream

用到了netty的UDP协议，获取到客户端传来的封包，通过content（）方法获取到客户端发来的消息内容
，获取到的是ByteBuf类型的，就用到了BytBuf转字节流，代码如下：

 @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, DatagramPacket datagramPacket) throws Exception {
        //content()方法获取发送者的内容
        ByteBuf byteBuf = datagramPacket.content();
        CCloudPacketParser cCloudPacketParser = new CCloudPacketParser();
        InputStream io = new ByteBufInputStream(byteBuf);
        CPacket12345 packet12345 = cCloudPacketParser.parse(io);

        System.out.println("获取到的数据：" + packet12345.getMsgType().getElevator_id());
        System.out.println("获取到的数据：" + packet12345.getMsgType().getMsg_type());
    }

使用netty的ByteBufInputStream（）即可得到想要的类型