php专区

疯了，不知道是CSDN抽风还是我忘了保存，昨晚写的博今天竟然没了。。看来又要重码一遍。。

微信可以回复视频给用户，也可以给用户广播图文消息，而对应的图片、视频、语音等都需要用户提前上传到微信服务器。上传成功后，微信会返回给开发者一个Media_id，可以通过media_id来调用该文件。

http请求方式: POST/FORM http://file.api.weixin.qq.com/cgi-bin/media/upload?access_token=ACCESS_TOKEN&type=TYPE

然我们看一下该接口所需要的参数：

上传的思路大致有了，首先建一个数据包，再把文件转化为流加入数据包，同时头文件在加入content-type等信息

最后再将数据包post到对应的url就好了。

来个控制器方法：

public string Upload() {
            string filename = System.Web.HttpContext.Current.Server.MapPath("/Images/carrot1.jpg");
            string url = "http://file.api.weixin.qq.com/cgi-bin/media/upload?access_token=" + finalstr.acctoken + "&type=image";
            
           // 上传一张图片，放在网站根目录images/carrot1.jpg下。
            return HttpHelper.HttpUploadFile(url, filename);
        }

下边上类中的代码

首先，需要参数content-type，那我们要写个方法来获取文件格式：

 private static string GetContentType(FileInfo fileInfo)
        {
            var contentType = "";
            switch (fileInfo.Extension.ToLower())
            {
                case ".jpg":
                    contentType = "image/jpeg";
                    break;
                case ".mp3":
                    contentType = "audio/mp3";
                    break;
                case ".amr":
                    contentType = "audio/amr";
                    break;
                case ".mp4":
                    contentType = "video/mp4";
                    break;
                default:
                    throw new NotSupportedException("文件格式不支持");
            }

            return contentType;
        }

 public static string HttpUploadFile(string url, string file)
        {   //判断文件是否存在
            if (!File.Exists(file))
            {
                throw new FileNotFoundException();
            }

            FileInfo fileInfo = new FileInfo(file);

            
            string result = string.Empty;
            string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
            byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("rn--" + boundary + "rn");
            //创建连接
            var request = (HttpWebRequest)WebRequest.Create(url);
            request.ContentType = "multipart/form-data; boundary=" + boundary;
            request.Method = "POST";
            request.KeepAlive = true;
            //构造数据包头文件的前半部分
            var stream = request.GetRequestStream();
            stream.Write(boundarybytes, 0, boundarybytes.Length);
            
            var headerTemplate = "Content-Disposition: form-data; name="{0}"; filename="{1}"rnContent-Type: {2}rnrn";
            var header = string.Format(headerTemplate, fileInfo.Name, file, GetContentType(fileInfo));
            var headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
            stream.Write(headerbytes, 0, headerbytes.Length);

            var fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
            var buffer = new byte[4096];
            var bytesRead = 0;
            while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
            {
                stream.Write(buffer, 0, bytesRead);//文件写入流
            }
            fileStream.Close();
            //构造数据包后半部分
            var trailer = System.Text.Encoding.ASCII.GetBytes("rn--" + boundary + "--rn");
            stream.Write(trailer, 0, trailer.Length);
            stream.Close();

            WebResponse wresp = null;
            try
            {
                wresp = request.GetResponse();

                Stream stream2 = wresp.GetResponseStream();
                StreamReader reader2 = new StreamReader(stream2);

                result = reader2.ReadToEnd();
            }
            finally
            {
                if (wresp != null)
                {
                    wresp.Close();
                    wresp = null;
                }
            }

            return result;
        }

   {"type":"TYPE","media_id":"MEDIA_ID","created_at":123456789}

当用户点击自定义菜单时候，微信会给开发者发送一个event事件

服务器接收之后，我们就可以给用户回复图片或者图文了

如何回复，参见：http://www.2cto.com/weixin/201408/324777.html