凌晨01:30 发一个求助 SOS 抓取远程无扩展名的图片

非常感谢园子里的各位朋友的关注与帮助

已近找到解决方案了  by 软件~民工

解决方案：

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通过判断文件内容的头2个字节可以确定文件格式
255216是jpg //7173是gif //6677是BMP //13780是PNG

结贴！！

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这是代码：

 1 <summary>
 2         /// 抓取远程图片 自动识别扩展名
 3         /// </summary>
 4         /// <param name="url"></param>
 5         /// <returns></returns>
 6         private string getRemoteImg(string url)
 7         {
 8             string rtnString = string.Empty;
 9             HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
10             request.Method = "GET";
11             try
12             {
13                 using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
14                 {
15                     string fileExt = string.Empty;
16                     string fileName = DateTime.Now.ToString("yyyyMMddhhmmssss");
17                     string FileExtNum = string.Empty;
18                     using (Stream stream = response.GetResponseStream())
19                     {
20                         byte[] retBytes = null;
21                         using (MemoryStream ms = new MemoryStream())
22                         {
23                             int b;
24                             int i = 0;
25                             while ((b = stream.ReadByte()) != -1)
26                             {
27                                 i++;
28                                 if (i <= 2)
29                                 {
30                                     FileExtNum += b.ToString();
31                                 }
32                                 ms.WriteByte((byte)b);
33                             }
34                             retBytes = ms.ToArray();
35                         }
36                         switch (FileExtNum)
37                         {
38                             case "255216":
39                                 fileExt = "jpg";
40                                 break;
41 
42                             case "7173":
43                                 fileExt = "gif";
44                                 break;
45 
46                             case "13780":
47                                 fileExt = "png";
48                                 break;
49 
50                             case "6677 ":
51                                 fileExt = "bmp";
52                                 break;
53                         }
54                         if (!string.IsNullOrEmpty(fileExt))
55                         {
56 
57                             if (!Directory.Exists(Application.StartupPath + "\\UploadFiles\\"))//若文件夹不存在则新建文件夹   
58                             {
59                                 Directory.CreateDirectory(Application.StartupPath + "\\UploadFiles\\"); //新建文件夹   
60                             }
61                             string localPath = Application.StartupPath + "\\UploadFiles\\" + fileName + "." + fileExt + "";
62                             using (FileStream fs = new FileStream(localPath, FileMode.Create))
63                             {
64                                 using (BinaryWriter sr = new BinaryWriter(fs))
65                                 {
66                                     sr.Write(retBytes, 0, retBytes.Length);
67                                     sr.Close(); fs.Close();
68                                     if (System.IO.File.Exists(localPath))
69                                     {
70                                         rtnString = "UploadFiles/" + fileName + "." + fileExt + "";
71                                     }
72                                 }
73                             }
74                         }
75                     }
76                 }
77             }
78             catch (Exception ex)
79             {
80                 throw ex;
81             }
82             return rtnString;

83         } 

这样的问题不应该发到首页来，但我实在是找不到方法了，百度GG都翻遍了，都没有找到方法来下载一个没有扩展名的图片。

由于图片没有扩展名 所下载的时候就不知道以什么样的格式来保存到本地。

图片如下： 可以点击右键去看下地址（因为直接发出地址，会有人说我广告嫌疑。）

所以请求园子里的高手写一个方法 能实现下载无扩展名的图片，并保存到本地(本地名称可以随便取)。若图片是JPG的 就保存为jpg，GIF的就保存为GIF

我在网上找了唯一一个说是下载无扩展名的图片的方法，但没用，我贴在下面供大家参考下。

        private void getImage(string url) {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.Method = "GET";
            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                string fileName = response.Headers.Get("Content-Disposition");
                
                fileName = fileName.Substring(fileName.IndexOf("\"") + 1, fileName.LastIndexOf("\"") - fileName.IndexOf("\"") - 1);
                byte[] buf = new byte[response.ContentLength];
                using (Stream stream = response.GetResponseStream())
                {
                    stream.Read(buf, 0, buf.Length);
                }
                using (FileStream fs = File.Open(@"D:\" + fileName, FileMode.Create))
                {
                    fs.Write(buf, 0, buf.Length);
                    fs.Flush();
                }
            }
        }