C#微信公众平台开发之高级群发接口

一、为了实现高级群发功能，需要解决的问题

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)。

C#微信公众平台开发之高级群发接口

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ID
string 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>();
 }
}

List<string> openidList = WXApi.GetopenIDs(access_token); //获取关注者OpenID列表
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\};
 }
}

C#微信公众平台开发之高级群发接口

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