我試圖通過API以編程方式將圖像上傳到另一臺服務(wù)器. API希望我在一個字節(jié)數(shù)組中上傳圖像,以便在字段中發(fā)送：“image_content”.
我的實現(xiàn)和調(diào)用代碼如下. Web請求命中服務(wù)器,但服務(wù)器響應(yīng)我的Web請求中不存在該圖像.
當(dāng)我運行以下代碼時,我收到的錯誤是圖像不在請求中.我在這里錯過了什么？
public static class FormUpload{ private static readonly Encoding encoding = Encoding.UTF8; public static HttpWebResponse MultipartFormDataPost(string postUrl, string userAgent, Dictionary<string, object> postParameters) { string formDataBoundary = String.Format("----------{0:N}", Guid.NewGuid()); string contentType = "multipart/form-data; boundary=" formDataBoundary; byte[] formData = GetMultipartFormData(postParameters, formDataBoundary); return PostForm(postUrl, userAgent, contentType, formData);}private static HttpWebResponse PostForm(string postUrl, string userAgent, string contentType, byte[] formData){ HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest; if (request == null) { throw new NullReferenceException("request is not a http request"); } // Set up the request properties. request.Method = "POST"; request.ContentType = contentType; request.UserAgent = userAgent; request.ContentLength = formData.Length; // Send the form data to the request. using (Stream requestStream = request.GetRequestStream()) { requestStream.Write(formData, 0, formData.Length); requestStream.Close(); } return request.GetResponse() as HttpWebResponse;}private static byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary){ Stream formDataStream = new System.IO.MemoryStream(); bool needsCLRF = false; foreach (var param in postParameters) { if (param.Value is FileParameter) { FileParameter fileToUpload = (FileParameter)param.Value; // Add just the first part of this param, since we will write the file data directly to the Stream string header = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"; filename=\"{2}\"\r\nContent-Type: {3}\r\n\r\n", boundary, param.Key, fileToUpload.FileName ?? param.Key, fileToUpload.ContentType ?? "application/octet-stream"); formDataStream.Write(encoding.GetBytes(header), 0, encoding.GetByteCount(header)); // Write the file data directly to the Stream, rather than serializing it to a string. formDataStream.Write(fileToUpload.File, 0, fileToUpload.File.Length); } else { string postData = string.Format("--{0}\r\nContent-Disposition: form-data; name=\"{1}\"\r\n\r\n{2}", boundary, param.Key, param.Value); formDataStream.Write(encoding.GetBytes(postData), 0, encoding.GetByteCount(postData)); } } // Add the end of the request. Start with a newline string footer = "\r\n--" boundary "--\r\n"; formDataStream.Write(encoding.GetBytes(footer), 0, encoding.GetByteCount(footer)); // Dump the Stream into a byte[] formDataStream.Position = 0; byte[] formData = new byte[formDataStream.Length]; formDataStream.Read(formData, 0, formData.Length); formDataStream.Close(); return formData;}public class FileParameter{ public byte[] File { get; set; } public string FileName { get; set; } public string ContentType { get; set; } public FileParameter(byte[] file) : this(file, null) { } public FileParameter(byte[] file, string filename) : this(file, filename, null) { } public FileParameter(byte[] file, string filename, string contenttype) { File = file; FileName = filename; ContentType = contenttype; }}}
調(diào)用上述函數(shù)的代碼是：
// Read file dataFileStream fs = new FileStream("c:\\myimage.jpeg", FileMode.Open, FileAccess.Read);byte[] data = new byte[fs.Length];fs.Read(data, 0, data.Length);fs.Close();// Generate post objectsDictionary<string, object> postParameters = new Dictionary<string, object>();postParameters.Add("image_content",data);// Create request and receive responsestring postURL = "myurl";string userAgent = "Mozilla";HttpWebResponse webResponse = FormUpload.MultipartFormDataPost(postURL, userAgent, postParameters);// Process responseStreamReader responseReader = new StreamReader(webResponse.GetResponseStream());string fullResponse = responseReader.ReadToEnd();webResponse.Close();Response.Write(fullResponse);解決方法:
在我看來,你應(yīng)該使用MultipartFormDataContent 類,因為它“為使用multipart / form-data MIME類型編碼的內(nèi)容提供容器.”.試試這個
public static HttpWebResponse MultipartFormDataPost(string postUrl, string userAgent, byte[] data) { string contentType; byte[] formData = Program.GetMultipartFormData(data, out contentType); return PostForm(postUrl, userAgent, contentType, formData); } public static byte[] GetMultipartFormData(byte[] data, out string contentType) { var byteArrayContent = new ByteArrayContent(data); byteArrayContent.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg"); byteArrayContent.Headers.Add("image_content", "myimage.jpeg"); var content = new MultipartFormDataContent(String.Format("----------{0:N}", Guid.NewGuid())) { byteArrayContent }; contentType = content.Headers.ContentType.ToString(); return content.ReadAsByteArrayAsync().Result; }