北斗數據包格式封裝和解析

1.北斗協議的具體格式如下圖

2.數據包類型 根據北斗協議類型定義如下枚舉類型

 /// <summary>
    /// 數據包類型
    /// </summary>
    public enum BDFrameType : ushort
    {
        /// <summary>
        /// 預設
        /// </summary>
        Default = 0x00,
 
        /// <summary>
        /// 終端通用應答
        /// </summary>
        TerCommonResponse = 0x0001,
 
        /// <summary>
        /// 平臺通用應答
        /// </summary>
        PlatCommonResponse = 0x8001,
 
        /// <summary>
        /// 終端心跳
        /// </summary>
        TerHeartbeat = 0x0002,
         
         
             /// <summary>
             /// 位置信息彙報
            /// </summary>
              Position = 0x0200
         
        //省略其他的數據包類型
 
    }

3.基礎類封裝 BDBaseFrame,使用 IByteBuffer 類來封裝數據包，IByteBuffer 內置提供了很多位元組操作方法（read，write） 

byteBuffer.ReadUnsignedShort()
byteBuffer.WriteUnsignedShort()
//等等

public abstract class BDBaseFrame
    {
        /// <summary>
        /// 消息ID
        /// </summary>
        public BDFrameType FrameType { get; set; }
 
        /// <summary>
        /// 是否分包
        /// </summary>
        public bool IsSubpackage { get; set; }
 
        /// <summary>
        /// 加密方式
        /// </summary>
        public BDFrameEncryptType FrameEncryptType { get; set; }
 
        /// <summary>
        /// 消息體長度
        /// </summary>
        public UInt16 FrameContentLen { get; private set; }
 
        /// <summary>
        /// 終端手機號  唯一
        /// </summary>
        public string TerminalPhone { get; set; } = string.Empty;
 
 
        /// <summary>
        /// 消息流水號
        /// </summary>
        public ushort FrameSerialNum { get; set; }
 
        /// <summary>
        /// 消息總包數
        /// </summary>
        public ushort FramePackageCount { get; set; }
 
        /// <summary>
        /// 包序號  從 1開始
        /// </summary>
        public ushort FramePackageIndex { get; set; }
 
 
        private int m_frameBodyOffset = 13;
 
        /// <summary>
        /// 消息體 數據偏於量
        /// </summary>
        protected int FrameBodyOffset
        {
            get { return m_frameBodyOffset; }
        }
 
        private static ushort m_SendFrameSerialNum = 0;
 
        /// <summary>
        /// 獲取發送的流水號
        /// </summary>
        public static ushort SendFrameSerialNum
        {
            get
            {
                if (m_SendFrameSerialNum == ushort.MaxValue)
                    m_SendFrameSerialNum = 0;
 
                m_SendFrameSerialNum++;
 
                return m_SendFrameSerialNum;
            }
        }
 
        /// <summary>
        /// 數據包內容 位元組
        /// </summary>
        //public IByteBuffer ContentBuffer { get; set; }
 
        #region 解析數據包
        /// <summary>
        /// 解析頭部
        /// </summary>
        private void DecoderHead(IByteBuffer byteBuffer)
        {
            //消息體屬性
            byteBuffer.SetReaderIndex(1);
            FrameType = (BDFrameType)byteBuffer.ReadUnsignedShort();
            ushort frameProerty = byteBuffer.ReadUnsignedShort();
            IsSubpackage = FrameHelper.ReadBoolean16(frameProerty, 13);
            FrameContentLen = (UInt16)(frameProerty & 0x1FFF);//消息體長度
            if (IsSubpackage)
                m_frameBodyOffset = 17;
            //終端手機號
            StringBuilder stringBuilder = new StringBuilder();
            for (int i = 0; i < 6; i++)
            {
                stringBuilder.Append(byteBuffer.ReadByte().ToString("X2"));
            }
            TerminalPhone = stringBuilder.ToString().TrimStart(new char[] { '0' });
            //消息流水號
            FrameSerialNum = byteBuffer.ReadUnsignedShort();
            //消息包封裝項
            if (IsSubpackage)
            {
                FramePackageCount = byteBuffer.ReadUnsignedShort();
                FramePackageIndex = byteBuffer.ReadUnsignedShort();
            }
        }
 
        /// <summary>
        /// 解析內容
        /// </summary>
        public virtual void DecoderFrame(IByteBuffer byteBuffer)
        {
            //解析頭部
            DecoderHead(byteBuffer);
        }
 
        #endregion
 
        #region 封裝數據包
 
        public virtual IByteBuffer EncoderContent()
        {
            return null;
        }
 
        #endregion
 
        public override string ToString()
        {
            return $"{TerminalPhone} {FrameTypeHelper.GetFrameType(FrameType)}  {DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")}";
        }
    }

4.具體數據包類型封裝 PositionFrame

 /// <summary>
    /// 位置信息彙報
    /// </summary>
    public class PositionFrame : BDBaseFrame
    {
        public PositionFrame()
        {
            FrameType = BDFrameType.Position;
        }
 
        /// <summary>
        /// 報警標誌
        /// </summary>
        public UInt32 AlarmFlag { get; set; }
 
        /// <summary>
        /// 狀態
        /// </summary>
        public UInt32 StatusFlag { get; set; }
 
        /// <summary>
        /// 緯度 DWORD 以度為單位的緯度值乘以 10 的 6 次方，精確到百萬分之一度
        /// </summary>
        public double Lat { get; set; }
 
        /// <summary>
        /// 經度 DWORD 以度為單位的經度值乘以 10 的 6 次方，精確到百萬分之一度
        /// </summary>
        public double Lng { get; set; }
 
        /// <summary>
        /// 高程 WORD 海拔高度，單位為米（m）
        /// </summary>
        public UInt16 Height { get; set; }
 
        /// <summary>
        /// 速度 WORD 1/10km/h
        /// </summary>
        public float Speed { get; set; }
 
        /// <summary>
        /// 方向 WORD 0-359，正北為 0，順時針
        /// </summary>
        public UInt16 Direction { get; set; }
 
        /// <summary>
        /// 時間 BCD[6] YY-MM-DD-hh-mm-ss（GMT+8 時間，本標準中之後涉及的時間均採用此時區）
        /// </summary>
        public DateTime GpsDateTime { get; set; }
 
        public override void DecoderFrame(IByteBuffer byteBuffer)
        {
            base.DecoderFrame(byteBuffer);
 
            AlarmFlag = byteBuffer.ReadUnsignedInt();
            StatusFlag = byteBuffer.ReadUnsignedInt();
            Lat = byteBuffer.ReadUnsignedInt() / 1000000.0;
            Lng = byteBuffer.ReadUnsignedInt() / 1000000.0;
            Height = byteBuffer.ReadUnsignedShort();
            Speed = byteBuffer.ReadUnsignedShort() / 10.0f;
            Direction = byteBuffer.ReadUnsignedShort();
            //時間 BCD[6]
            byte[] bcdTime = new byte[6];
            byteBuffer.ReadBytes(bcdTime);
            string bcdTimeString = FrameHelper.Bcd2String(bcdTime);
            DateTime gpsTime;
            if (DateTime.TryParseExact(bcdTimeString, "yyMMddHHmmss", new CultureInfo("zh-CN", true), DateTimeStyles.None, out gpsTime))
                GpsDateTime = gpsTime;
            else
                GpsDateTime = new DateTime(2001, 1, 1, 0, 0, 0);
        }
 
 
        public override IByteBuffer EncoderContent()
        {
            IByteBuffer contentBuffer = Unpooled.Buffer(100, 1024);
            contentBuffer.WriteInt((int)AlarmFlag);
            contentBuffer.WriteInt((int)StatusFlag);
            contentBuffer.WriteInt((int)(Lat * 1000000));
            contentBuffer.WriteInt((int)(Lng * 1000000));
            contentBuffer.WriteUnsignedShort(Height);
            contentBuffer.WriteUnsignedShort((UInt16)(Speed * 10));
            contentBuffer.WriteUnsignedShort(Direction);
            //時間 BCD[6]
            byte[] timeBcdBuffer = FrameHelper.WriteBCDString(GpsDateTime.ToString("yyMMddHHmmss"));
            contentBuffer.WriteBytes(timeBcdBuffer);
            return contentBuffer;
        }
 
        public override string ToString()
        {
            return string.Format("通訊號:{0},時間:{1},經緯度{2}|{3},高度:{4},方向:{5}", TerminalPhone, GpsDateTime.ToString("yyyy-MM-dd HH:mm:ss"), Lng, Lat, Height, Direction);
        }
    }

5.dotnetty EncoderHandler 封裝，上面封裝的只是消息體的數據，沒有包括標識位，消息頭，驗證碼，標識位，在發送數據通道中，需要把數據加上標識位，消息頭，驗證碼，標識位。包括數據包轉義

 /// <summary>
    /// 北斗數據包 封裝
    /// </summary>
    public class BeiDouContentEncoderHandler : MessageToByteEncoder<BDBaseFrame>
    {
        protected override void Encode(IChannelHandlerContext context, BDBaseFrame message, IByteBuffer output)
        {
            EncodeFrame(message, output);
        }
 
        private void EncodeFrame(BDBaseFrame message, IByteBuffer output)
        {
            //IByteBuffer frameBuffer = output;
            output.MarkReaderIndex();
            //內容
            IByteBuffer contentBuffer = message.EncoderContent();
            if (contentBuffer == null)
                contentBuffer = Unpooled.Empty;
            //byte[] content = new byte[contentBuffer.ReadableBytes];
            //contentBuffer.ReadBytes(content, 0, content.Length);
            //寫頭標誌
            output.WriteByte(BDFrameConst.FRAME_FLAG);
            //消息 ID
            output.WriteUnsignedShort((ushort)message.FrameType);
            //消息體屬性  加密沒做
            // ushort contentLen = (ushort)content.Length;
            ushort contentLen = (ushort)contentBuffer.ReadableBytes;
            if (message.IsSubpackage)
            {
                contentLen = (ushort)(contentLen | 0x2000);
                output.WriteUnsignedShort(contentLen);
            }
            else
            {
                output.WriteUnsignedShort(contentLen);
            }
            //終端手機號
            string tPhone = message.TerminalPhone.ToStringFramePropertyLength(12, '0');
            byte[] tPhoneBuffer = CZEFrameHelper.WriteBCDString(tPhone);
            output.WriteBytes(tPhoneBuffer);
            //消息流水號
            output.WriteUnsignedShort(message.FrameSerialNum);
            //消息包封裝項
            if (message.IsSubpackage)
            {
                output.WriteUnsignedShort(message.FramePackageCount);
                output.WriteUnsignedShort(message.FramePackageIndex);
            }
            //消息體
            output.WriteBytes(contentBuffer);
            contentBuffer.Release();
            //計算校驗碼
            byte[] checkCodeBuffer = new byte[output.ReadableBytes];
            output.ReadBytes(checkCodeBuffer, 0, checkCodeBuffer.Length);
            byte value = checkCodeBuffer[1];
            for (int i = 2; i < checkCodeBuffer.Length; i++)
                value ^= checkCodeBuffer[i];
            output.WriteByte(value);
            //寫尾標誌
            output.WriteByte(BDFrameConst.FRAME_FLAG);
            //轉義
            output.ResetReaderIndex();
            checkCodeBuffer = new byte[output.ReadableBytes];
            output.ReadBytes(checkCodeBuffer, 0, checkCodeBuffer.Length);
            byte[] frame = FrameEscaping.BDEscapingBufferSend(checkCodeBuffer);
 
            //數據寫入 frameBuffer
            output.Clear();
            output.WriteBytes(frame);
        }
 
    }

6.使用 BeiDouContentEncoderHandler，在通道中加入BeiDouContentEncoderHandler，通道裡面的順序很重要，BeiDouContentEncoderHandler必須要在你發送的Handler前加到通道中去如下圖

主要的代碼就這些，水平有限，請大家多多指教

原文地址 http://www.dncblogs.cn/Blog/LookBlog/71