/// <summary>
        /// 打开shp、shx文件流
        /// 读取shp、shx信息时需要首先执行此操作
        /// 同时操作头文件读取和ShxRecord、ShpRecord示例化
        /// </summary>
        /// <param name="ofs"></param>
        public void Open(Stream shpStream, Stream shxStream)
        {
            if (mShpFile != null)
            {
                Close();
            }

            mShpFile       = shpStream;
            mShxFile       = shxStream;
            mShpFileReader = null;
            mShpFileWriter = null;
            mShxFileReader = null;
            mShxFileWriter = null;
            if (mShpFile.CanRead)
            {
                mShpFileReader = new BinaryReader(mShpFile);
            }
            if (mShpFile.CanWrite)
            {
                mShpFileWriter = new BinaryWriter(mShpFile);
            }

            if (mShxFile.CanRead)
            {
                mShxFileReader = new BinaryReader(mShxFile);
            }
            if (mShxFile.CanWrite)
            {
                mShxFileWriter = new BinaryWriter(mShxFile);
            }
            //reset position
            mRecordsReadCount = 0;
            //assume header is not written
            mHeaderWritten = false;

            //read the header
            if (shpStream.CanRead)
            {
                //try to read the header...
                try
                {
                    mHeader.Read(mShpFileReader);
                    mHeaderWritten = true;
                }
                catch (EndOfStreamException)
                {
                    //could not read header, file is empty
                    mHeader        = new ShpHeader();
                    mHeaderWritten = false;
                }
            }
            if (mShpFile != null)
            {
                mIsReadOnly    = !mShpFile.CanWrite;
                mIsForwardOnly = !mShpFile.CanSeek;
            }
            mShxRecord = new ShxRecord(mHeader);
            mShpRecord = new ShpRecord(mHeader);
        }
        /// <summary>
        /// 写入文件
        /// </summary>
        /// <param name="shpStream"></param>
        /// <param name="shxStream"></param>
        public void Creat(Stream shpStream, Stream shxStream)
        {
            if (mShpFile != null)
            {
                Close();
            }

            mShpFile       = shpStream;
            mShxFile       = shxStream;
            mShpFileWriter = null;
            mShxFileWriter = null;
            //if (mShpFile.CanRead)
            //    mShpFileReader = new BinaryReader(mShpFile);
            if (mShpFile.CanWrite)
            {
                mShpFileWriter = new BinaryWriter(mShpFile);
            }

            //if (mShxFile.CanRead)
            //    mShxFileReader = new BinaryReader(mShxFile);
            if (mShxFile.CanWrite)
            {
                mShxFileWriter = new BinaryWriter(mShxFile);
            }
            //reset position
            //mRecordsReadCount = 0;
            //assume header is not written
            mFileCreat = true;

            if (mShpFile != null)
            {
                mIsReadOnly    = !mShpFile.CanWrite;
                mIsForwardOnly = !mShpFile.CanSeek;
            }
            //mShxRecord = new ShxRecord(mHeader);
            mShpRecord = new ShpRecord(mHeader);
        }