涉及access_token的获取请参考 《c#微信公众平台开发之access_token的获取存储与更新》
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)。
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测试数据/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测试数据/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测试数据/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测试数据/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\"}" ;
}
}
以上就是本文的全部内容，希望对大家的学习有所帮助。
dy("nrwz");
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