以下是代码片段：

[DllImport("kernel32.dll")]
        public static extern IntPtr CreateFileMapping(IntPtr hFile,
            IntPtr lpFileMappingAttributes, uint flProtect,
            uint dwMaximumSizeHigh,
            uint dwMaximumSizeLow, string lpName);

        [DllImport("kernel32.dll")]
        public static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject, uint
            dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow,
            IntPtr dwNumberOfBytesToMap);

        [DllImport("kernel32.dll")]
        public static extern bool UnmapViewOfFile(IntPtr lpBaseAddress);

        [DllImport("kernel32.dll")]
        public static extern bool CloseHandle(IntPtr hObject);

        [DllImport("kernel32.dll")]
        public static extern IntPtr CreateFile(string lpFileName,
            int dwDesiredAccess, FileShare dwShareMode, IntPtr securityAttrs,
            FileMode dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile);

        [DllImport("kernel32.dll")]
        public static extern uint GetFileSize(IntPtr hFile, IntPtr lpFileSizeHigh);

上面是API的引用

 private string returnback(string path)
        {
            string str = "";
            IntPtr vFileHandle = CreateFile(path,
        GENERIC_READ | GENERIC_WRITE, FileShare.Read | FileShare.Write,
        IntPtr.Zero, FileMode.Open,
        FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, IntPtr.Zero);
            if (INVALID_HANDLE_VALUE != (int)vFileHandle)
            {
                IntPtr vMappingHandle = CreateFileMapping(
                    vFileHandle, IntPtr.Zero, PAGE_READWRITE, 0, 0, "~MappingTemp");
                if (vMappingHandle != IntPtr.Zero)
                {
                    IntPtr vHead = MapViewOfFile(vMappingHandle,
                        FILE_MAP_COPY | FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, IntPtr.Zero);
                    if (vHead != IntPtr.Zero)
                    {
                        uint vSize = GetFileSize(vFileHandle, IntPtr.Zero);
                        byte[] temp = new byte[vSize];
                        for (int i = 0; i < vSize; i++)
                        {
                            byte vTemp = Marshal.ReadByte((IntPtr)((int)vHead + i));
                            temp[i] = vTemp;
                        }
                        ASCIIEncoding encoding = new ASCIIEncoding();
                        str = encoding.GetString(temp).Replace("\r\n", ",");
                        UnmapViewOfFile(vHead);
                    }
                    CloseHandle(vMappingHandle);
                    CloseHandle(vHead);
                }
                CloseHandle(vFileHandle);
               
            }
            return str;
        }

上面具体的读取方法。