C#、python企业微信群机器人自动发送文件

1. 基本HTTP POST发送方式

• 表单提交协议规定：
  要先将 HTTP 要求的 Content-Type 设为 multipart/form-data，而且要设定一个 boundary 参数，
  这个参数是由应用程序自行产生，它会用来识别每一份资料的边界 (boundary)，
  用以产生多重信息部份 (message part)。
  而 HTTP 服务器可以抓取 HTTP POST 的信息，
  基本内容：
  1. 每个信息部份都要用 --[BOUNDARY_NAME] 来包装，以分隔出信息的每个部份，而最后要再加上一个 --[BOUNDARY_NAME] 来表示结束。
  2. 每个信息部份都要有一个 Content-Disposition: form-data; name=""，而 name 设定的就是 HTTP POST 的键值 (key)。
  3. 声明区和值区中间要隔两个新行符号（\r\n）。
  4. 中间可以夹入二进制资料，但二进制资料必须要格式化为二进制字符串。
  5. 若要设定不同信息段的资料型别 (Content-Type)，则要在信息段内的声明区设定。

• 因此两个form内容模板为
  boundary = "----" + DateTime.Now.Ticks.ToString("x");//程序生成
  1.文本内容
  "\r\n--" + boundary +
  "\r\nContent-Disposition: form-data; name=\"键\"; filename=\"文件名\"" +
  "\r\nContent-Type: application/octet-stream" +
  "\r\n\r\n";
  2.文件内容
  "\r\n--" + boundary +
  "\r\nContent-Disposition: form-data; name=\"键\"" +
  "\r\n\r\n内容";

• Python方法

def upload_file(file_path, wx_upload_url):
    file_name = file_path.split("/")[-1]
    with open(file_path, 'rb') as f:
        length = os.path.getsize(file_path)
        data = f.read()
    headers = {"Content-Type": "application/octet-stream"}
    params = {
        "filename": file_name,
        "filelength": length,
    }
    file_data = copy(params)
    file_data['file'] = (file_path.split('/')[-1:][0], data)
    encode_data = encode_multipart_formdata(file_data)
    file_data = encode_data[0]
    headers['Content-Type'] = encode_data[1]
    print(headers)

    r = requests.post(wx_upload_url, data=file_data, headers=headers)
    print(r.text)
    media_id = r.json()['media_id']
    return media_id


# media_id 通过上一步上传的方法获得
def qi_ye_wei_xin_file(wx_url, media_id):
    headers = {"Content-Type": "text/plain"}
    data = {
        "msgtype": "file",
        "file": {
            "media_id": media_id
        }
    }
    r = requests.post(
        url=wx_url,
        headers=headers, json=data)

• C#实现方式

•    class FormItemModel
      {
          /// 
  
          /// 表单键，request["key"]
          /// 
          public string Key { set; get; }
          /// 
  
          /// 表单值,上传文件时忽略，request["key"].value
          /// 
          public string Value { set; get; }
          /// 
  
          /// 是否是文件
          /// 
          public bool IsFile
          {
              get
              {
                  if (FileContent == null || FileContent.Length == 0)
                      return false;
  
                  if (FileContent != null && FileContent.Length > 0 && string.IsNullOrWhiteSpace(FileName))
                      throw new Exception("上传文件时 FileName 属性值不能为空");
                  return true;
              }
          }
          /// 
  
          /// 上传的文件名
          /// 
          public string FileName { set; get; }
          /// 
  
          /// 上传的文件内容
          /// 
          public byte[] FileContent { set; get; }
      }
  
  
          public static string PostForm(string url, List formItems, CookieContainer cookieContainer = null, string refererUrl = null, Encoding encoding = null, int timeOut = 20000)
          {
              HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
              #region 初始化请求对象
              request.Method = "POST";
              request.Timeout = timeOut;
              request.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
              request.KeepAlive = true;
              request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36";
              if (!string.IsNullOrEmpty(refererUrl))
                  request.Referer = refererUrl;
              if (cookieContainer != null)
                  request.CookieContainer = cookieContainer;
              #endregion
  
              string boundary = "----" + DateTime.Now.Ticks.ToString("x");//分隔符
              request.ContentType = string.Format("multipart/form-data; boundary={0}", boundary);
              //请求流
              var postStream = new MemoryStream();
              #region 处理Form表单请求内容
              //是否用Form上传文件
              var formUploadFile = formItems != null && formItems.Count > 0;
              if (formUploadFile)
              {
                  //文件数据模板
                  string fileFormdataTemplate =
                      "\r\n--" + boundary +
                      "\r\nContent-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"" +
                      "\r\nContent-Type: application/octet-stream" +
                      "\r\n\r\n";
                  //文本数据模板
                  string dataFormdataTemplate =
                      "\r\n--" + boundary +
                      "\r\nContent-Disposition: form-data; name=\"{0}\"" +
                      "\r\n\r\n{1}";
                  foreach (var item in formItems)
                  {
                      string formdata = null;
                      if (item.IsFile)
                      {
                          //上传文件
                          formdata = string.Format(
                              fileFormdataTemplate,
                              item.Key, //表单键
                              item.FileName);
                      }
                      else
                      {
                          //上传键值对
                          formdata = string.Format(
                              dataFormdataTemplate,
                              item.Key,
                              item.Value);
                      }
  
                      //统一处理
                      byte[] formdataBytes = null;
                      //第一行不需要换行
                      if (postStream.Length == 0)
                          formdataBytes = Encoding.UTF8.GetBytes(formdata.Substring(2, formdata.Length - 2));
                      else
                          formdataBytes = Encoding.UTF8.GetBytes(formdata);
                      postStream.Write(formdataBytes, 0, formdataBytes.Length);
  
                      //写入文件内容
                      if (item.FileContent != null && item.FileContent.Length > 0)
                      {
                          postStream.Write(item.FileContent, 0, item.FileContent.Length);
                      }
                  }
                  //结尾
                  var footer = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
                  postStream.Write(footer, 0, footer.Length);
  
              }
              else
              {
                  request.ContentType = "application/x-www-form-urlencoded";
              }
              #endregion
  
              request.ContentLength = postStream.Length;
  
              #region 输入二进制流
              if (postStream != null)
              {
                  postStream.Position = 0;
                  //直接写入流
                  Stream requestStream = request.GetRequestStream();
  
                  byte[] buffer = new byte[1024];
                  int bytesRead = 0;
                  while ((bytesRead = postStream.Read(buffer, 0, buffer.Length)) != 0)
                  {
                      requestStream.Write(buffer, 0, bytesRead);
                  }
                  postStream.Close();//关闭文件访问
              }
              #endregion
  
              HttpWebResponse response = (HttpWebResponse)request.GetResponse();
              if (cookieContainer != null)
              {
                  response.Cookies = cookieContainer.GetCookies(response.ResponseUri);
              }
  
              using (Stream responseStream = response.GetResponseStream())
              {
                  using (StreamReader myStreamReader = new StreamReader(responseStream, encoding ?? Encoding.UTF8))
                  {
                      string retString = myStreamReader.ReadToEnd();
                      return retString;
                  }
              }
          }
          public static string Send_file(string Url, string media_id)
          {
              HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(Url);
              req.Method = "POST";
              req.ContentType = "application/octet-stream";//设置对应的ContentType
              string postdata = "{\"msgtype\": \"file\",\"file\": {\"media_id\":\""+ media_id+"\"}}";
              byte[] data = Encoding.UTF8.GetBytes(postdata);//把字符串转换为字节
  
              Stream writer = req.GetRequestStream();//获取
              writer.Write(data, 0, data.Length);
              writer.Flush();
              HttpWebResponse response = (HttpWebResponse)req.GetResponse();//获取服务器返回的结果
              Stream getStream = response.GetResponseStream();
              StreamReader streamreader = new StreamReader(getStream);
              String result = streamreader.ReadToEnd();
              return result;
          }
  

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