[WebMethod]
        public bool AddAssistSpeech(AssistSpeech assistSpeech, string fileName, byte[] fileStream, out string msg)
        {
            try
                {
                    // 上传文件
                    assistSpeech.AudioPath = (new AssistSpeechAudioFileHelper()).Upload(fileName, fileStream);
                    // 保存数据库等其他操作为返回结果result和输出信息msg赋值
                    ……
                    return result;
                }
                catch (Exception ex)
                {
                    Loger.LogErr(ex);
                    msg = ex.Message;
                    return false;
                }
        }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.IO;

namespace Xinbohit.Com.CommonWebService.Classes
{
    class AssistSpeechAudioFileHelper
    {
        /// <summary>
        /// 上传文件，返回相对路径以便存库
        /// </summary>
        /// <param name="fileName">源文件名</param>
        /// <param name="fileStream">文件数据流</param>
        /// <returns></returns>
        public string Upload(string fileName, byte[] fileStream)
        {
            DateTime now = DateTime.Now;
            string relativepath = Path.Combine(now.ToString("yyyyMMdd"), now.ToString("yyyyMMddhhmmssfff") + Path.GetExtension(fileName));
            string basePath = GetBasePath();

            string savePath = Path.Combine(basePath, relativepath);
            string saveDir = Path.GetDirectoryName(savePath);
            if (!Directory.Exists(saveDir))
            {
                Directory.CreateDirectory(saveDir);
            }

            using (FileStream stream = new FileStream(savePath, FileMode.Create))
            {
                stream.Write(fileStream, 0, fileStream.Length);
                stream.Flush();
            }

            return relativepath;
        }

        /// <summary>
        /// 下载音频文件
        /// </summary>
        /// <param name="fileNameRelativepath"></param>
        /// <returns></returns>
        public byte[] DownLoad(string fileNameRelativepath, out string msg)
        {
            string basePath = GetBasePath();
            string filePath = Path.Combine(basePath, fileNameRelativepath);
            if (File.Exists(filePath))
            {
                byte[] result;

                using (FileStream stream = new FileStream(filePath, FileMode.Open))
                {
                    long length = stream.Length;
                    result = new byte[length];

                    long bytesToRead = length;
                    int buffer = 1024;
                    int offset = 0;
                    int byteNum = 0;

                    while (bytesToRead > 0)
                    {
                        if (buffer < bytesToRead)
                        {
                            byteNum = stream.Read(result, offset, buffer);
                        }
                        else
                        {
                            byteNum = stream.Read(result, offset, (int)bytesToRead);
                        }

                        if (byteNum == 0)
                        {
                            break;
                        }

                        offset += byteNum;
                        bytesToRead -= byteNum;
                    }
                }
                msg = string.Empty;
                return result;
            }
            else
            {
                msg = "文件不存在。";
                return new byte[0];
            }
        }

        private string GetBasePath()
        {
            string basePath = System.Configuration.ConfigurationManager.AppSettings["AudioFileBasePath"];

            if (!Directory.Exists(basePath))
            {
                Directory.CreateDirectory(basePath);
            }

            return basePath;
        }
    }
}