Question

鉴于以下尝试将数据发布到生成PDF文件的Web服务， PDF rocket （顺便说一句）。

我收到错误无效的URI：uri字符串太长
为什么有人会对POST数据施加任意限制？

using (var client = new HttpClient())
{
    // Build the conversion options
    var options = new Dictionary<string, string>
    {
        { "value", html },
        { "apikey", ConfigurationManager.AppSettings["pdf:key"] },
        { "MarginLeft", "10" },
        { "MarginRight", "10" }
    };

    // THIS LINE RAISES THE EXCEPTION
    var content = new FormUrlEncodedContent(options);

    var response = await client.PostAsync("https://api.html2pdfrocket.com/pdf", content);
    var result = await response.Content.ReadAsByteArrayAsync();
    return result;
}

我收到了这个错误的错误。

 {System.UriFormatException: Invalid URI: The Uri string is too long.
   at System.UriHelper.EscapeString
   at System.Uri.EscapeDataString
   at System.Net.Http.FormUrlEncodedContent.Encode
   at System.Net.Http.FormUrlEncodedContent.GetContentByteArray

这让我想起640k应该足够......我的意思是真的吗？

Answer 1

使用帖子可以在http消息中包含内容而不是URI。 uri的最大长度为2083个字符。您可以在http消息中将其作为JSON发送而不是URI，这是在HttpPost / HttpPut中发送更大块数据的推荐方法。我改变了你的代码来使用它。这假设您正在联系的服务可以使用JSON（.net Web Api开箱即用应该没有问题。）

using (var client = new HttpClient())
{
    // Build the conversion options
    var options = new 
    {
        value = html,
        apikey = ConfigurationManager.AppSettings["pdf:key"],
        MarginLeft = "10",
        MarginRight = "10"
    };

    // Serialize our concrete class into a JSON String
    var stringPayload = JsonConvert.SerializeObject(options);
    var content = new StringContent(stringPayload, Encoding.UTF8, "application/json");

    var response = await client.PostAsync("https://api.html2pdfrocket.com/pdf", content);
    var result = await response.Content.ReadAsByteArrayAsync();
    return result;
}

确保安装newtonsoft json。

Answer 2

我刚解决了类似的问题。对我来说，我正在与我无法控制的后端集成，并且必须将POST文件与表单数据（例如customerID）一起作为表单变量。因此切换到JSON或Multipart会破坏我无法控制的后端。问题是大文件会导致FormUrlEncodedContent抛出错误，说“uri字符串太长”。

这是经过两天努力后为我解决的代码（注意仍然需要调整为ASYNC）。

private string UploadFile(string filename, int CustomerID, byte[] ImageData) {

        string Base64String = "data:image/jpeg;base64," + Convert.ToBase64String(ImageData, 0, ImageData.Length);

        var baseAddress = new Uri("[PUT URL HERE]");
        var cookieContainer = new CookieContainer();
        using (var handler = new HttpClientHandler() { AllowAutoRedirect = true, UseCookies = true, CookieContainer = cookieContainer })
        using (var client = new HttpClient(handler) { BaseAddress = baseAddress })
        {

            try {

                //ENCODE THE FORM VARIABLES DIRECTLY INTO A STRING rather than using a FormUrlEncodedContent type which has a limit on its size.        
                string FormStuff = string.Format("name={0}&file={1}&id={2}", filename, HttpUtility.UrlEncode(Base64String), CustomerID.ToString());
                //THEN USE THIS STRING TO CREATE A NEW STRINGCONTENT WHICH TAKES A PARAMETER WHICH WILL FormURLEncode IT AND DOES NOT SEEM TO THROW THE SIZE ERROR
                StringContent content = new StringContent(FormStuff, Encoding.UTF8, "application/x-www-form-urlencoded");

                //UPLOAD
                string url = string.Format("/ajax/customer_image_upload.php");
                response = client.PostAsync(url, content).Result;
                return response.Content.ToString();

            }
            catch (Exception ex) {
                return ex.ToString();
            }



        }

    }

Answer 3

如果像我一样，您遇到了一些仅接受表单内容的不稳定的第三方Web服务，则可以解决以下问题：

// Let's assume you've got your key-value pairs organised into a nice Dictionary<string, string> called formData
var encodedItems = formData.Select(i => WebUtility.UrlEncode(i.Key) + "=" + WebUtility.UrlEncode(i.Value));
var encodedContent = new StringContent(String.Join("&", encodedItems), null, "application/x-www-form-urlencoded");

// Post away!
var response = await client.PostAsync(url, encodedContent);

Answer 4

@Mick Byrne：谢谢-您的解决方案像个魔术一样起作用！

这是我完整的代码：

      public async Task DateienSendenAsync (string PfadUndDatei, string Dateiname, String VRPinGUID, String ProjektGUID, String VRPinX, String VRPinY, String VRPinZ)
    {
        var client = new HttpClient();
        // Create the HttpContent for the form to be posted.
        var requestContent = new[] {
                            new KeyValuePair<string, string>("dateiname", Dateiname),

                            new KeyValuePair<string, string>("bild", Convert.ToBase64String(File.ReadAllBytes(PfadUndDatei))),
                            new KeyValuePair<string, string>("VRPinGUID", VRPinGUID),
                            new KeyValuePair<string, string>("ProjektGUID", ProjektGUID),
                            new KeyValuePair<string, string>("ebene", "ebene"),
                            new KeyValuePair<string, string>("raumnummer", "raumnummer"),
                            new KeyValuePair<string, string>("ansichtsname", "ansichtsname"),
                            new KeyValuePair<string, string>("VRPinX", VRPinX),
                            new KeyValuePair<string, string>("VRPinY", VRPinY),
                            new KeyValuePair<string, string>("VRPinZ", VRPinZ),

                            };

        String url = "http://yourhomepage/path/upload.php";

        var encodedItems = requestContent.Select(i => WebUtility.UrlEncode(i.Key) + "=" + WebUtility.UrlEncode(i.Value));
        var encodedContent = new StringContent(String.Join("&", encodedItems), null, "application/x-www-form-urlencoded");

        // Post away!
        var response = await client.PostAsync(url, encodedContent);



    }

HttpClient：uri字符串太长

4 个答案: