C#微信公众平台开发—高级群发接口

1、通过微信接口上传图文消息素材时，Json中的图片不是url而是media_id，如何通过微信接口上传图片并获取图片的media_id？

2、图片存储在什么地方，如何获取？

二、实现步骤，以根据OpenID列表群发图文消息为例

1、准备数据

我把数据存储在数据库中，ImgUrl字段是图片在服务器上的相对路径(这里的服务器是自己的服务器，不是微信的哦)。

从数据库中获取数据放到DataTable中：

DataTable dt = ImgItemDal.GetImgItemTable(loginUser.OrgID, data);

2、通过微信接口上传图片，返回图片的media_id

取ImgUrl字段数据，通过MapPath方法获取图片在服务器上的物理地址，用FileStream类读取图片，并上传给微信

HTTP上传文件代码(HttpRequestUtil类)：

/// <summary>  /// Http上传文件  /// </summary>  public static string HttpUploadFile(string url, string path)  {      // 设置参数      HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;      CookieContainer cookieContainer = new CookieContainer();      request.CookieContainer = cookieContainer;      request.AllowAutoRedirect = true;      request.Method = "POST";      string boundary = DateTime.Now.Ticks.ToString("X"); // 随机分隔线      request.ContentType = "multipart/form-data;charset=utf-8;boundary=" + boundary;      byte[] itemBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");      byte[] endBoundaryBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");        int pos = path.LastIndexOf("\\");      string fileName = path.Substring(pos + 1);        //请求头部信息       StringBuilder sbHeader = new StringBuilder(string.Format("Content-Disposition:form-data;name=\"file\";filename=\"{0}\"\r\nContent-Type:application/octet-stream\r\n\r\n", fileName));      byte[] postHeaderBytes = Encoding.UTF8.GetBytes(sbHeader.ToString());        FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);      byte[] bArr = new byte[fs.Length];      fs.Read(bArr, 0, bArr.Length);      fs.Close();        Stream postStream = request.GetRequestStream();      postStream.Write(itemBoundaryBytes, 0, itemBoundaryBytes.Length);      postStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);      postStream.Write(bArr, 0, bArr.Length);      postStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);      postStream.Close();        //发送请求并获取相应回应数据      HttpWebResponse response = request.GetResponse() as HttpWebResponse;      //直到request.GetResponse()程序才开始向目标网页发送Post请求      Stream instream = response.GetResponseStream();      StreamReader sr = new StreamReader(instream, Encoding.UTF8);      //返回结果网页（html）代码      string content = sr.ReadToEnd();      return content;  }

请求微信接口，上传图片，返回media_id(WXApi类)：

/// <summary>  /// 上传媒体返回媒体ID  /// </summary>  public static string UploadMedia(string access_token, string type, string path)  {      // 设置参数      string url = string.Format("http://file.api.weixin.qq.com/cgi-bin/media/upload?access_token={0}&type={1}", access_token, type);      return HttpRequestUtil.HttpUploadFile(url, path);  }

string msg = WXApi.UploadMedia(access_token, "image", path);   // 上图片返回媒体IDstring media_id = Tools.GetJsonValue(msg, "media_id");

传入的path(aspx.cs文件中的代码)：

string path = MapPath(data);

一个图文消息由若干条图文组成，每条图文有标题、内容、链接、图片等

遍历每条图文数据，分别请求微信接口，上传图片，获取media_id

3、上传图文消息素材

拼接图文消息素材Json字符串(ImgItemDal类(操作图文消息表的类))：

/// <summary>  /// 拼接图文消息素材Json字符串  /// </summary>  public static string GetArticlesJsonStr(PageBase page, string access_token, DataTable dt)  {      StringBuilder sbArticlesJson = new StringBuilder();        sbArticlesJson.Append("{\"articles\":[");      int i = 0;      foreach (DataRow dr in dt.Rows)      {          string path = page.MapPath(dr["ImgUrl"].ToString());          if (!File.Exists(path))          {              return "{\"code\":0,\"msg\":\"要发送的图片不存在\"}";          }          string msg = WXApi.UploadMedia(access_token, "image", path); // 上图片返回媒体ID          string media_id = Tools.GetJsonValue(msg, "media_id");          sbArticlesJson.Append("{");          sbArticlesJson.Append("\"thumb_media_id\":\"" + media_id + "\",");          sbArticlesJson.Append("\"author\":\"" + dr["Author"].ToString() + "\",");          sbArticlesJson.Append("\"title\":\"" + dr["Title"].ToString() + "\",");          sbArticlesJson.Append("\"content_source_url\":\"" + dr["TextUrl"].ToString() + "\",");          sbArticlesJson.Append("\"content\":\"" + dr["Content"].ToString() + "\",");          sbArticlesJson.Append("\"digest\":\"" + dr["Content"].ToString() + "\",");          if (i == dt.Rows.Count - 1)          {              sbArticlesJson.Append("\"show_cover_pic\":\"1\"}");          }          else          {              sbArticlesJson.Append("\"show_cover_pic\":\"1\"},");          }          i++;      }      sbArticlesJson.Append("]}");        return sbArticlesJson.ToString();  }

上传图文消息素材，获取图文消息的media_id：

/// <summary>  /// 请求Url，发送数据  /// </summary>  public static string PostUrl(string url, string postData)  {      byte[] data = Encoding.UTF8.GetBytes(postData);        // 设置参数      HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;      CookieContainer cookieContainer = new CookieContainer();      request.CookieContainer = cookieContainer;      request.AllowAutoRedirect = true;      request.Method = "POST";      request.ContentType = "application/x-www-form-urlencoded";      request.ContentLength = data.Length;      Stream outstream = request.GetRequestStream();      outstream.Write(data, 0, data.Length);      outstream.Close();        //发送请求并获取相应回应数据      HttpWebResponse response = request.GetResponse() as HttpWebResponse;      //直到request.GetResponse()程序才开始向目标网页发送Post请求      Stream instream = response.GetResponseStream();      StreamReader sr = new StreamReader(instream, Encoding.UTF8);      //返回结果网页（html）代码      string content = sr.ReadToEnd();      return content;  }

/// <summary>  /// 上传图文消息素材返回media_id  /// </summary>  public static string UploadNews(string access_token, string postData)  {      return HttpRequestUtil.PostUrl(string.Format("https://api.weixin.qq.com/cgi-bin/media/uploadnews?access_token={0}", access_token), postData);  }

string articlesJson = ImgItemDal.GetArticlesJsonStr(this, access_token, dt);  string newsMsg = WXApi.UploadNews(access_token, articlesJson);  string newsid = Tools.GetJsonValue(newsMsg, "media_id");

4、群发图文消息

获取全部关注者OpenID集合(WXApi类)：

/// <summary>  /// 获取关注者OpenID集合  /// </summary>  public static List<string> GetOpenIDs(string access_token)  {      List<string> result = new List<string>();        List<string> openidList = GetOpenIDs(access_token, null);      result.AddRange(openidList);        while (openidList.Count > 0)      {          openidList = GetOpenIDs(access_token, openidList[openidList.Count - 1]);          result.AddRange(openidList);      }        return result;  }    /// <summary>  /// 获取关注者OpenID集合  /// </summary>  public static List<string> GetOpenIDs(string access_token, string next_openid)  {      // 设置参数      string url = string.Format("https://api.weixin.qq.com/cgi-bin/user/get?access_token={0}&next_openid={1}", access_token, string.IsNullOrWhiteSpace(next_openid) ? "" : next_openid);      string returnStr = HttpRequestUtil.RequestUrl(url);      int count = int.Parse(Tools.GetJsonValue(returnStr, "count"));      if (count > 0)      {          string startFlg = "\"openid\":[";          int start = returnStr.IndexOf(startFlg) + startFlg.Length;          int end = returnStr.IndexOf("]", start);          string openids = returnStr.Substring(start, end - start).Replace("\"", "");          return openids.Split(',').ToList<string>();      }      else      {          return new List<string>();      }  }

拼接图文消息Json(WXMsgUtil类)：

/// <summary>  /// 图文消息json  /// </summary>  public static string CreateNewsJson(string media_id, List<string> openidList)  {      StringBuilder sb = new StringBuilder();      sb.Append("{\"touser\":[");      sb.Append(string.Join(",", openidList.ConvertAll<string>(a => "\"" + a + "\"").ToArray()));      sb.Append("],");      sb.Append("\"msgtype\":\"mpnews\",");      sb.Append("\"mpnews\":{\"media_id\":\"" + media_id + "\"}");      sb.Append("}");      return sb.ToString();  }

群发代码：

resultMsg = WXApi.Send(access_token, WXMsgUtil.CreateNewsJson(newsid, openidList));

/// <summary>  /// 根据OpenID列表群发  /// </summary>  public static string Send(string access_token, string postData)  {      return HttpRequestUtil.PostUrl(string.Format("https://api.weixin.qq.com/cgi-bin/message/mass/send?access_token={0}", access_token), postData);  }

供群发按钮调用的方法(data是传到页面的id，根据它从数据库中取数据)：

/// <summary>  /// 群发  /// </summary>  public string Send()  {      string type = Request["type"];      string data = Request["data"];        string access_token = AdminUtil.GetAccessToken(this); //获取access_token      List<string> openidList = WXApi.GetOpenIDs(access_token); //获取关注者OpenID列表      UserInfo loginUser = AdminUtil.GetLoginUser(this); //当前登录用户         string resultMsg = null;        //发送文本      if (type == "1")      {          resultMsg = WXApi.Send(access_token, WXMsgUtil.CreateTextJson(data, openidList));      }        //发送图片      if (type == "2")      {          string path = MapPath(data);          if (!File.Exists(path))          {              return "{\"code\":0,\"msg\":\"要发送的图片不存在\"}";          }          string msg = WXApi.UploadMedia(access_token, "image", path);          string media_id = Tools.GetJsonValue(msg, "media_id");          resultMsg = WXApi.Send(access_token, WXMsgUtil.CreateImageJson(media_id, openidList));      }        //发送图文消息      if (type == "3")      {          DataTable dt = ImgItemDal.GetImgItemTable(loginUser.OrgID, data);          string articlesJson = ImgItemDal.GetArticlesJsonStr(this, access_token, dt);          string newsMsg = WXApi.UploadNews(access_token, articlesJson);          string newsid = Tools.GetJsonValue(newsMsg, "media_id");          resultMsg = WXApi.Send(access_token, WXMsgUtil.CreateNewsJson(newsid, openidList));      }        //结果处理      if (!string.IsNullOrWhiteSpace(resultMsg))      {          string errcode = Tools.GetJsonValue(resultMsg, "errcode");          string errmsg = Tools.GetJsonValue(resultMsg, "errmsg");          if (errcode == "0")          {              return "{\"code\":1,\"msg\":\"\"}";          }          else          {              return "{\"code\":0,\"msg\":\"errcode:"                  + errcode + ", errmsg:"                  + errmsg + "\"}";          }      }      else      {          return "{\"code\":0,\"msg\":\"type参数错误\"}";      }  }

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