``` // <summary>          /// 创建固定大小的临时文件          /// </summary>          /// <param name="fileName">文件名</param>          /// <param name="fileSize">文件大小</param>          /// <param name="overwrite">允许覆写：可以覆盖掉已经存在的文件</param>          public static void CreateFixedSizeFile(string fileName, long fileSize)         {             //验证参数              if (string.IsNullOrEmpty(fileName) || new[] { Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar }.Contains(                     fileName[fileName.Length - 1]))                 throw new ArgumentException("fileName");             if (fileSize < 0) throw new ArgumentException("fileSize");             //创建目录              string dir = Path.GetDirectoryName(fileName);             if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))                 Directory.CreateDirectory(dir);             //创建文件              FileStream fs = null;             try             {                 fs = new FileStream(fileName, FileMode.Create);                 fs.SetLength(fileSize); //设置文件大小              }             catch             {                 if (fs != null)                 {                     fs.Close();                     File.Delete(fileName); //注意，若由fs.SetLength方法产生了异常，同样会执行删除命令，请慎用overwrite:true参数，或者修改删除文件代码。                  }                 throw;             }             finally             {                 if (fs != null) fs.Close();             }         }         /// <summary>         /// 读取大文件用,读取文件前面指定长度字节数         /// </summary>         /// <param name="filePath">文件路径</param>         /// <param name="readByteLength">读取长度,单位字节</param>         /// <returns></returns>         public byte[] ReadBigFile(string filePath,int readByteLength)         {              FileStream stream = new FileStream(filePath,FileMode.Open);             byte[] buffer = new byte[readByteLength];             stream.Read(buffer, 0, readByteLength);             stream.Close();             stream.Dispose();             return buffer;             //string str = Encoding.Default.GetString(buffer) //如果需要转换成编码字符串的话         }         /// <summary>         /// 普通文件读取方法         /// </summary>         /// <param name="path"></param>         /// <returns></returns>         public string ReaderFile(string path)         {             string fileData = string.Empty;             ///读取文件的内容                  StreamReader reader = new StreamReader(path, Encoding.Default);             fileData = reader.ReadToEnd();             reader.Close();             reader.Dispose();             return fileData;         } ``` 原文链接：https://blog.csdn.net/u013628121/article/details/52577702