使用Graph API将图像从.NET发布到Facebook墙 [英] Posting image from .NET to Facebook wall using the Graph API
问题描述
我正在使用Facebook的Javascript API来开发需要能够将图像发布到用户墙的应用程序。
这个应用程序的一部分需要是服务器端的，因为它需要将图像数据发布为multipart / form-data。
$ b $注意：这不是使用post的简单版本，而是真正的照片方法。
http://graph.facebook.com/me/photos
我想我'面对两个问题，一个.NET和一个Facebook问题：
Facebook问题：我不太确定所有参数是否应该发送作为多部分/表单数据（包括access_token和消息）。唯一的代码示例是使用cUrl util / application。
.NET问题：我从来没有发布多部分/表单数据请求.NET，我不知道.NET是否自动创建mime部分，或者我必须以某种特殊方式编码参数。
这有点很难调试，因为我从Graph API获得的唯一错误响应是400 - 不好的请求。
下面是我决定写这个问题时看的代码（是的，这有点冗长： - ）
最终的答案当然是一个从.NET发布图像的示例代码片段，但是我可以更少的解决。
string username = null;
string password = null;
int timeout = 5000;
string requestCharset =UTF-8;
string responseCharset =UTF-8;
string parameters =;
string responseContent =;
string finishedUrl =https://graph.facebook.com/me/photos;
parameters =access_token =+ facebookAccessToken +& message = This + is + an + image;
HttpWebRequest request = null;
request =（HttpWebRequest）WebRequest.Create（finishedUrl）;
request.Method =POST;
request.KeepAlive = false;
// application / x-www-form-urlencoded | multipart / form-data
request.ContentType =multipart / form-data;
request.Timeout = timeout;
request.AllowAutoRedirect = false;
如果（username！= null&& username！=&& &&密码！= null&&密码！=）
{
request.PreAuthenticate =真正;
request.Credentials = new NetworkCredential（username，password）.GetCredential（new Uri（finishedUrl），Basic）;
}
//写参数以请求身体
流requestBodyStream = request.GetRequestStream（）;
Encoding requestParameterEncoding = Encoding.GetEncoding（requestCharset）;
byte [] parametersForBody = requestParameterEncoding.GetBytes（parameters）;
requestBodyStream.Write（parametersForBody，0，parametersForBody.Length）;
/ *
这不工作
byte [] startParm = requestParameterEncoding.GetBytes（& source =）;
requestBodyStream.Write（startParm，0，startParm.Length）;
byte [] fileBytes = File.ReadAllBytes（Server.MapPath（images / sample.jpg））;
requestBodyStream.Write（fileBytes，0，fileBytes.Length）;
* /
requestBodyStream.Close（）;
HttpWebResponse response = null;
Stream receiveStream = null;
StreamReader readStream = null;
Encoding responseEncoding = System.Text.Encoding.GetEncoding（responseCharset）;
try
{
response =（HttpWebResponse）request.GetResponse（）;
receiveStream = response.GetResponseStream（）;
readStream = new StreamReader（receiveStream，responseEncoding）;
responseContent = readStream.ReadToEnd（）;
}
finally
{
if（receiveStream！= null）
{
receiveStream.Close（）;
}
if（readStream！= null）
{
readStream.Close（）;
}
if（response！= null）
{
response.Close（）;
}
}
是如何上传二进制数据的示例。但是上传到/ me / photos不会将图像发布到墙壁（图像保存到您的应用程序的专辑中，我被困在如何在feed中发布，另一种方法是将图像发布到Wall专辑，通过URL == graph.facebook.com/%wall-album-id%/photos ，但没有找到任何方法来创建这样的相册（用户在上传时创建它
{
string boundary =----------- ----------------+ DateTime.Now.Ticks.ToString（x）;
uploadRequest =（HttpWebRequest）WebRequest.Create（@https：// graph.facebook.com/me/photos）;
uploadRequest.ServicePoint.Expect100Continue = false;
uploadRequest.Method =POST;
uploadRequest.UserAgent =Mozilla / 4.0 ; Windows NT）;
uploadRequest.ContentType =multipart / form-data; boundary =+ boundary;
uploadRequest.KeepAlive = false;
StringBuilder sb = new StringBuilder （）;
string formdataT emplate = - {0} \r\\\
Content-Disposition：form-data; name = \{1} \\r\\\
\r\\\
{2} \r\\\
;
sb.AppendFormat（formdataTemplate，boundary，access_token PercentEncode（FacebookAccessToken））;
sb.AppendFormat（formdataTemplate，boundary，message，PercentEncode（This is a image））;
string headerTemplate = - {0} \r\\\
Content-Disposition：form-data;名称= \ {1} \; filename = \{2} \\r\\\
Content-Type：{3} \r\\\
\r\\\
;
sb.AppendFormat（headerTemplate，boundary， source，file.png，@application / octet-stream）;
string formString = sb.ToString（）;
byte [] formBytes = Encoding.UTF8.GetBytes （formString）;
byte [] trailingBytes = Encoding.UTF8.GetBytes（\r\\\
--+ boundary +--\\\）;
long imageLength = imageMemoryStream.Length;
long contentLength = formBytes.Length + imageLength + trailingBytes.Length;
uploadRequest.ContentLength = contentLength;
uploadRequest.AllowWriteStreamBuffering = false;
流strm_out = uploadRequest.GetRequestStream（）;
strm_out.Write（formBytes，0，formBytes.Length）;
byte [] buffer = new Byte [检查（（uint）Math.Min（4096，（int）imageLength））];
int bytesRead = 0;
int bytesTotal = 0;
imageMemoryStream.Seek（0，SeekOrigin.Begin ）;
while（（bytesRead = imageMemoryStream.Read（buffer，0，buffer.Length））！= 0）
{
strm_out.Write（buffer，0，bytesRead）; bytesTotal + = bytesRead;
gui.OnUploadProgress（this，（int）（bytesTotal * 100 / imageLength））;
}
strm_out.Write（trailingBytes，0，trailingBytes.Length）;
strm_out.Close（）;
HttpWebResponse wresp = uploadRequest.GetResponse（）作为HttpWebResponse;
}
I'm using the Facebooks Javascript API to develop an application that will need to be able to post an image to a users wall. That part of the app needs to be server-side as far as I can tell, since it needs to post the image data as "multipart/form-data".
Note: It's not the simple version using "post", but the real "photos" method.
http://graph.facebook.com/me/photos
I think I'm facing two problems, a .NET and a Facebook problem:
Facebook problem: I'm not quite sure if all parameters should be send as multipart/form-data (including the access_token and message). The only code example there is uses the cUrl util/application.
.NET problem: I have never issued multipart/form-data requests from .NET , and I'm not sure if .NET automatically creates the mime-parts, or if I have to encode the parameters in some special way.
It's a bit hard to debug, since the only error response I get from the Graph API is "400 - bad request". Below is the code as it looked when I decided to write this question (yes, it's a bit verbose :-)
The ultimate answer would of course be a sample snippet posting an image from .NET, but I can settle for less.
string username = null;
string password = null;
int timeout = 5000;
string requestCharset = "UTF-8";
string responseCharset = "UTF-8";
string parameters = "";
string responseContent = "";
string finishedUrl = "https://graph.facebook.com/me/photos";
parameters = "access_token=" + facebookAccessToken + "&message=This+is+an+image";
HttpWebRequest request = null;
request = (HttpWebRequest)WebRequest.Create(finishedUrl);
request.Method = "POST";
request.KeepAlive = false;
//application/x-www-form-urlencoded | multipart/form-data
request.ContentType = "multipart/form-data";
request.Timeout = timeout;
request.AllowAutoRedirect = false;
if (username != null && username != "" && password != null && password != "")
{
request.PreAuthenticate = true;
request.Credentials = new NetworkCredential(username, password).GetCredential(new Uri(finishedUrl), "Basic");
}
//write parameters to request body
Stream requestBodyStream = request.GetRequestStream();
Encoding requestParameterEncoding = Encoding.GetEncoding(requestCharset);
byte[] parametersForBody = requestParameterEncoding.GetBytes(parameters);
requestBodyStream.Write(parametersForBody, 0, parametersForBody.Length);
/*
This wont work
byte[] startParm = requestParameterEncoding.GetBytes("&source=");
requestBodyStream.Write(startParm, 0, startParm.Length);
byte[] fileBytes = File.ReadAllBytes(Server.MapPath("images/sample.jpg"));
requestBodyStream.Write( fileBytes, 0, fileBytes.Length );
*/
requestBodyStream.Close();
HttpWebResponse response = null;
Stream receiveStream = null;
StreamReader readStream = null;
Encoding responseEncoding = System.Text.Encoding.GetEncoding(responseCharset);
try
{
response = (HttpWebResponse) request.GetResponse();
receiveStream = response.GetResponseStream();
readStream = new StreamReader( receiveStream, responseEncoding );
responseContent = readStream.ReadToEnd();
}
finally
{
if (receiveStream != null)
{
receiveStream.Close();
}
if (readStream != null)
{
readStream.Close();
}
if (response != null)
{
response.Close();
}
}
Here is a sample of how to upload binary data. But an uploading to /me/photos won't publish the image into wall :( The image saving into your app's album. I'm stuck on how to announce it in the feed. Yet another way is to post an image into "Wall Album", by URL=="graph.facebook.com/%wall-album-id%/photos". But didn't found any way to create sucha album (user creates it when uploading an image via the site).
{
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
uploadRequest = (HttpWebRequest)WebRequest.Create(@"https://graph.facebook.com/me/photos");
uploadRequest.ServicePoint.Expect100Continue = false;
uploadRequest.Method = "POST";
uploadRequest.UserAgent = "Mozilla/4.0 (compatible; Windows NT)";
uploadRequest.ContentType = "multipart/form-data; boundary=" + boundary;
uploadRequest.KeepAlive = false;
StringBuilder sb = new StringBuilder();
string formdataTemplate = "--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}\r\n";
sb.AppendFormat(formdataTemplate, boundary, "access_token", PercentEncode(facebookAccessToken));
sb.AppendFormat(formdataTemplate, boundary, "message", PercentEncode("This is an image"));
string headerTemplate = "--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\"\r\nContent-Type: {3}\r\n\r\n";
sb.AppendFormat(headerTemplate, boundary, "source", "file.png", @"application/octet-stream");
string formString = sb.ToString();
byte[] formBytes = Encoding.UTF8.GetBytes(formString);
byte[] trailingBytes = Encoding.UTF8.GetBytes("\r\n--" + boundary + "--\r\n");
long imageLength = imageMemoryStream.Length;
long contentLength = formBytes.Length + imageLength + trailingBytes.Length;
uploadRequest.ContentLength = contentLength;
uploadRequest.AllowWriteStreamBuffering = false;
Stream strm_out = uploadRequest.GetRequestStream();
strm_out.Write(formBytes, 0, formBytes.Length);
byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)imageLength))];
int bytesRead = 0;
int bytesTotal = 0;
imageMemoryStream.Seek(0, SeekOrigin.Begin);
while ((bytesRead = imageMemoryStream.Read(buffer, 0, buffer.Length)) != 0)
{
strm_out.Write(buffer, 0, bytesRead); bytesTotal += bytesRead;
gui.OnUploadProgress(this, (int)(bytesTotal * 100 / imageLength));
}
strm_out.Write(trailingBytes, 0, trailingBytes.Length);
strm_out.Close();
HttpWebResponse wresp = uploadRequest.GetResponse() as HttpWebResponse;
}
这篇关于使用Graph API将图像从.NET发布到Facebook墙的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
