.net 直接输出远程文件到浏览器和下载文件保存到本机

利用了xmlhttp，实现代码比较简单具体实现如下：

首先bin文件引入，com->microsoft xml v3.0

具体代码如下:

protected void Button1_Click(object sender, EventArgs e)
    {
        string FileNames = "201406251824392435.pdf", ContentType = "";
        string houzhui = FileNames.Substring(FileNames.LastIndexOf("."));
        ContentType = checktype(FileNames);
        string Url = "http://xxx.xxx.xxx.xxx:8089/upfile/wenku/" + FileNames;//域名或者ip地址
        string StringFileName = Url.Substring(Url.LastIndexOf("/") + 1);
        string StringFilePath = Request.PhysicalApplicationPath;
        if (!StringFilePath.EndsWith("/")) StringFilePath += "/";
        try
        {
            MSXML2.XMLHTTP _xmlhttp = new MSXML2.XMLHTTPClass();
            _xmlhttp.open("GET", Url, false, null, null);
            _xmlhttp.send("");
            if (_xmlhttp.readyState == 4)//数据接收完毕
            {
                if (_xmlhttp.status == 200)//是否返回正确数据
                {
                    HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode("测试" + houzhui, System.Text.Encoding.UTF8));
                    HttpContext.Current.Response.ContentType = ContentType;
                    HttpContext.Current.Response.BinaryWrite((byte[])_xmlhttp.responseBody);//输出二进制到浏览器
                    HttpContext.Current.Response.Flush();
                    HttpContext.Current.Response.End();
                }
                else
                { Response.Write("错误：" + _xmlhttp.statusText + " 未找到要下载的文件!"); }
            }
            else
            {
                Response.Write("错误：" + _xmlhttp.statusText + " 请求的http地址不对！");
                Response.End();
            }
        }
        catch (Exception ex)
        {
            Response.Write("错误：无法找到请求的资源！");
            Response.End();
        }

    }

返回mime类型：

private static string checktype(string filename)
    {
        string ContentType;
        string houzhui = filename.Substring(filename.LastIndexOf(".") + 1).Trim().ToLower();
        switch (houzhui)
        {
            case ".asf":
                ContentType = "video/x-ms-asf ";
                break;
            case ".avi":
                ContentType = "video/avi ";
                break;
            case ".doc":
                ContentType = "application/msword ";
                break;
            case ".zip":
                ContentType = "application/zip ";
                break;
            case ".xls":
                ContentType = "application/vnd.ms-excel ";
                break;
            case ".gif":
                ContentType = "image/gif ";
                break;
            case ".jpg":
                ContentType = "image/jpeg ";
                break;
            case "jpeg":
                ContentType = "image/jpeg ";
                break;
            case ".wav":
                ContentType = "audio/wav ";
                break;
            case ".mp3":
                ContentType = "audio/mpeg3 ";
                break;
            case ".mpg":
                ContentType = "video/mpeg ";
                break;
            case ".mepg":
                ContentType = "video/mpeg ";
                break;
            case ".rtf":
                ContentType = "application/rtf ";
                break;
            case ".html":
                ContentType = "text/html ";
                break;
            case ".htm":
                ContentType = "text/html ";
                break;
            case ".txt":
                ContentType = "text/plain ";
                break;
            case ".pdf":
                ContentType = "application/pdf";
                break;
            default:
                ContentType = "application/octet-stream ";
                break;
        }
        return ContentType;
    }

下载文件并保存到本机：

  

 /// <summary>
    /// 获取远程文件到本地
    /// </summary>
    /// <param name="url">远程文件地址</param>
    /// <param name="path">本地路径</param>
    private static void DownUrltoFile(string url, string path)
    {
        string Cookie = String.Empty;
        String refer = url.Substring(0, url.LastIndexOf("/") + 1);
        System.Net.HttpWebRequest req = System.Net.HttpWebRequest.Create(url) as System.Net.HttpWebRequest;
        req.AllowAutoRedirect = false;
        req.Referer = refer;
        req.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13";
        System.Net.HttpWebResponse res = req.GetResponse() as System.Net.HttpWebResponse;
        System.Net.WebHeaderCollection headers = res.Headers;
        String newUrl = "";
        if ((res.StatusCode == System.Net.HttpStatusCode.Found) ||
          (res.StatusCode == System.Net.HttpStatusCode.Redirect) ||
          (res.StatusCode == System.Net.HttpStatusCode.Moved) ||
          (res.StatusCode == System.Net.HttpStatusCode.MovedPermanently))
        {
            newUrl = headers["Location"];
            newUrl = newUrl.Trim();
        }

        if (headers["Set-Cookie"] != null)
        {
            Cookie = headers["Set-Cookie"];
        }
        res.Close();
        req = null;
        String fileName = newUrl.Substring(newUrl.LastIndexOf("/") + 1);
        req = System.Net.HttpWebRequest.Create(url) as System.Net.HttpWebRequest;
        req.AllowAutoRedirect = true;
        req.Referer = url;
        req.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13";
        res = req.GetResponse() as System.Net.HttpWebResponse;
        System.IO.Stream stream = res.GetResponseStream();
        byte[] buffer = new byte[32 * 1024];
        int bytesProcessed = 0;
        System.IO.FileStream fs = System.IO.File.Create(HttpContext.Current.Server.MapPath(path));
        int bytesRead;
        do
        {
            bytesRead = stream.Read(buffer, 0, buffer.Length);
            fs.Write(buffer, 0, bytesRead);
            bytesProcessed += bytesRead;
        }
        while (bytesRead > 0);
        fs.Flush();
        fs.Close();
        res.Close();
    }

　　

HttpWebRequest,下载远程文件输出到浏览器

    调用：ReadFileWriterBinary("http://1.1.1.1:8889/xxx/xxx/xxx.pdf", "xx.pdf");
    
    private void ReadFileWriterBinary(String path, String fileName)
    {
        HttpWebRequest myWebRequest = (HttpWebRequest)WebRequest.Create(path);
        HttpWebResponse myWebResponse = (HttpWebResponse)myWebRequest.GetResponse();
        Stream readStream = myWebResponse.GetResponseStream();
        BinaryReader SplitFileReader = new BinaryReader(readStream);
        HttpContext.Current.Response.ContentType = "application/save";
        HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
        byte[] TempBytes = SplitFileReader.ReadBytes(Convert.ToInt32(myWebResponse.ContentLength));
        HttpContext.Current.Response.BinaryWrite(TempBytes);
        SplitFileReader.Close();
        readStream.Close();
    }

　　

 完善后，注释掉的是本地的处理：

/// <summary>          
        /// 下载文件          
        /// </summary>          
        /// <param name="URL">下载文件地址</param>         
        /// <param name="Filename">下载后的存放地址</param>                 
        public string DownloadFile(string URL, string filename)
        {
            try
            {
                System.Net.HttpWebRequest Myrq = (System.Net.HttpWebRequest)
                System.Net.HttpWebRequest.Create(URL);
                System.Net.HttpWebResponse myrp = (System.Net.HttpWebResponse)Myrq.GetResponse();
                long totalBytes = myrp.ContentLength;
                if (myrp.ContentLength != 0)
                {  
                    System.IO.Stream st = myrp.GetResponseStream();
                    //System.IO.Stream so = new System.IO.FileStream(filename,System.IO.FileMode.Create);

                    Response.Clear();
                    long totalDownloadedByte = 0;
                    byte[] by = new byte[1024];
                    int osize = st.Read(by, 0, (int)by.Length);
                    Response.ContentType = "application/octet-stream";
                    Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename));
                    while (osize > 0)
                    {
                        totalDownloadedByte = osize + totalDownloadedByte;
                        Response.OutputStream.Write(by, 0, osize);
                        Response.Flush();
                        //so.Write(by, 0, osize);
                        osize = st.Read(by, 0, (int)by.Length);
                    }
                    Response.Close();

                    //long totalDownloadedByte = 0;
                    //byte[] by = new byte[1024];
                    //int osize = st.Read(by, 0, (int)by.Length);
                    //while (osize > 0)
                    //{
                    //    totalDownloadedByte = osize + totalDownloadedByte;
                    //    so.Write(by, 0, osize);
                    //    osize = st.Read(by, 0, (int)by.Length);
                    //}
                    //so.Close();
                    st.Close();
                    return "success";
                }
                else
                {
                    return "文件不存在";
                }
            }
            catch (System.Exception e)
            {
                return "下载文件失败！" + e.ToString();
            }
        }