下载方法收集

1.方法一：WebRequest下载，下载路径包含http

 /// <summary>
        /// 网络文件下载
        /// </summary>
        /// <param name="p_strUrl">网络地址</param>
        /// <param name="saveFileName">文件名称</param>
        /// <returns>true-下载成功  false-下载失败</returns>
        /// </remarks>
        public static bool FileDownload(string p_strUrl, string saveFileName)
        {
            try
            {
                WebRequest webRequest = WebRequest.Create(p_strUrl);
                //读取文件流
                Stream stream = webRequest.GetResponse().GetResponseStream();

                byte[] fileByte = new byte[512];

                MemoryStream ms = new MemoryStream();
                int index = 0;
                while (true)
                {
                    index = stream.Read(fileByte, 0, fileByte.Length);
                    if (index == 0)
                    {
                        break;
                    }
                    //写进内存流
                    ms.Write(fileByte, 0, index);
                }
                byte[] array = ms.ToArray();
                saveFileName = string.IsNullOrEmpty(saveFileName) == true ? p_strUrl.Split('/')[p_strUrl.Split('/').Length - 1] : saveFileName;
                 //添加文件头
                // 判断浏览器类型添加文件头 update by X.Y
                if (HttpContext.Current.Request.UserAgent.ToLower().IndexOf("msie") > -1)
                {
                    saveFileName = ToHexString(saveFileName);
                }
                if (HttpContext.Current.Request.UserAgent.ToLower().IndexOf("firefox") > -1)
                {
                    HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=\"" + saveFileName + "\"");
                }
                else
                {
                    HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + saveFileName);
                }
                System.Web.HttpContext.Current.Response.AddHeader("Content-Length", array.Length.ToString());
                System.Web.HttpContext.Current.Response.ContentType = "application/octet-stream";
                System.Web.HttpContext.Current.Response.Charset = "UTF-8";
                System.Web.HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;
                System.Web.HttpContext.Current.Response.BinaryWrite(array);
                System.Web.HttpContext.Current.Response.Flush();
                System.Web.HttpContext.Current.Response.Clear();
            }
            catch
            {
                return false;
            }

            return true;
        }

2.方法二：文件流下载方法，下载路径不包含http

/// <summary>
        /// 功能: 输出文件
        /// </summary>
        /// <param name="fileHttpUrl">文件网络地址</param>
        /// <param name="saveFileName">保存默认文件名</param>
        public void ResponseWriteFile(string fileHttpUrl, string saveFileName)
        {
            try
            {
                // 创建文件信息实体
                FileInfo fileInfo = new FileInfo(fileHttpUrl);
                saveFileName = string.IsNullOrEmpty(saveFileName) == true ? fileHttpUrl.Split('/')[fileHttpUrl.Split('/').Length - 1] : saveFileName;

                if (fileInfo.Exists == true)
                {
                    //每次只读取100K
                    const long unitSize = 102400;
                    byte[] buffer = new byte[unitSize];

                    // 清空Response
                    HttpContext.Current.Response.Clear();

                    // 创建文件流
                    FileStream fileStream = File.OpenRead(fileHttpUrl);
                    long fileLength = fileStream.Length;

                    HttpContext.Current.Response.ContentType = "application/octet-stream";

                    // 判断浏览器类型添加文件头
                    if (HttpContext.Current.Request.UserAgent.ToLower().IndexOf("msie") > -1)
                    {
                        saveFileName = ToHexString(saveFileName);
                    }
                    if (HttpContext.Current.Request.UserAgent.ToLower().IndexOf("firefox") > -1)
                    {
                        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=\"" + saveFileName + "\"");
                    }
                    else
                    {
                        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment;filename=" + saveFileName);
                    }

                    // 循环输出文件
                    while (fileLength > 0 && HttpContext.Current.Response.IsClientConnected)
                    {
                        int readLength = fileStream.Read(buffer, 0, Convert.ToInt32(unitSize));
                        HttpContext.Current.Response.OutputStream.Write(buffer, 0, readLength);
                        HttpContext.Current.Response.Flush();
                        fileLength = fileLength - readLength;
                    }

                    HttpContext.Current.Response.Close();
                }
                else
                {
                 //("下载失败，文件不存在！");
                }
            }
            catch(Exception ex)
            {
               
              //("下载失败，请联系管理员或重试！");
            }
        }

3.编码

        /// <summary>
        /// Encodes non-US-ASCII characters in a string.
        /// </summary>
        /// <param name="s"></param>
        /// <returns></returns>
        public static string ToHexString(string s)
        {
            char[] chars = s.ToCharArray();
            StringBuilder builder = new StringBuilder();
            for (int index = 0; index < chars.Length; index++)
            {
                bool needToEncode = NeedToEncode(chars[index]);
                if (needToEncode)
                {
                    string encodedString = ToHexString(chars[index]);
                    builder.Append(encodedString);
                }
                else
                {
                    builder.Append(chars[index]);
                }
            }

            return builder.ToString();
        }

        /// <summary>
        /// Determines if the character needs to be encoded.
        /// </summary>
        /// <param name="chr"></param>
        /// <returns></returns>
        private static bool NeedToEncode(char chr)
        {
            string reservedChars = "$-_.+!*'(),@=&";

            if (chr > 127)
                return true;
            if (char.IsLetterOrDigit(chr) || reservedChars.IndexOf(chr) >= 0)
                return false;

            return true;
        }

        /// <summary>
        /// Encodes a non-US-ASCII character.
        /// </summary>
        /// <param name="chr"></param>
        /// <returns></returns>
        private static string ToHexString(char chr)
        {
            UTF8Encoding utf8 = new UTF8Encoding();
            byte[] encodedBytes = utf8.GetBytes(chr.ToString());
            StringBuilder builder = new StringBuilder();
            for (int index = 0; index < encodedBytes.Length; index++)
            {
                builder.AppendFormat("%{0}", Convert.ToString(encodedBytes[index], 16));
            }

            return builder.ToString();
        }