如何使用C#处理401错误响应？

我有一个

API

，它返回

json响应

。 当我从

Fiddler

调用

API

时，它会给我

json响应

如下图所示：

JSON响应：

从网页调用API:

protected void FinalCall()
    {

       // try
       // {
            string url = txtdomainURL.Text.Trim(); 
            string apiname = txtAPIname.Text.Trim();
            string apiURL = apiname+"/"+txtStoreID.Text.Trim()+"/"+txtSerialNo.Text.Trim(); //"duediligence/1/45523354232323424";// 990000552672620";//45523354232323424";
            //duediligence/1/45523354232323424 HTTP/1.1
            string storeID = txtStoreID.Text.Trim();//Test Store ID:1 Live Store ID: 2
            string partnerID = txtPartnerID.Text.Trim();// "1";
            string scretKey = txtSecretKey.Text.Trim();// "234623ger787qws3423";
            string requestBody = txtRequestBody.Text.Trim(); //"{\"category\": 8}";
            string data = scretKey + requestBody;


            string signatureHash = SHA1HashStringForUTF8String(data);
            lblSignatureHash.Text = signatureHash;
            String userName = partnerID;
            String passWord = signatureHash;
            string credentials = userName + ":" + passWord;//Convert.ToBase64String(Encoding.ASCII.GetBytes(userName + ":" + passWord));
            var dataString = JsonConvert.SerializeObject(requestBody); //JsonConvert.SerializeObject(requestBody);
            var bytes = Encoding.Default.GetBytes(dataString);


            WebClient client = new WebClient();
            string base64 = Convert.ToBase64String(Encoding.ASCII.GetBytes(credentials));
            client.Headers[HttpRequestHeader.Authorization] = "Basic " + Convert.ToBase64String(Encoding.ASCII.GetBytes(credentials));
            lblBase64.Text = base64;

            client.Headers.Add(HttpRequestHeader.Accept, "application/json");
            client.Headers.Add(HttpRequestHeader.ContentType, "application/json");
            //string response = cli.UploadString(url + apiURL, dataString); //"{some:\"json data\"}"
            string completeURLRequest = url + apiURL;

            //I GET ERROR HERE 
            var result = client.DownloadString(completeURLRequest);
            //CODE below this line is not executed

            //Context.Response.TrySkipIisCustomErrors = true;
            var serializer = new System.Web.Script.Serialization.JavaScriptSerializer();
            var jsonObject = serializer.DeserializeObject(result.ToString());
            //var result1 = client.UploadData(completeURLRequest, "POST", bytes);
            Response.Write(result);
            txtwebresponse.Text = jsonObject.ToString();
        //}

现在，当从网页执行相同的操作时，它会抛出

exeception

'401未授权异常'

。因此，我不想显示错误页面，而是想读取返回的

JSON

错误响应（如在fiddler中）并向用户显示

谢谢你的帮助

改编自：

---

稍微改变了SilentTremor的回答。结合using语句可以使代码稍微短一点

 catch (WebException ex)
 {
            HttpWebResponse httpResponse = (HttpWebResponse)ex.Response;
            using (WebResponse response = ex.Response)
            using (Stream data = response.GetResponseStream())
            using (StreamReader reader = new StreamReader(data))
            {
                string errorMessage = reader.ReadToEnd();
            }
 }

---

你好@SilentTremor，谢谢你的回复。它工作得很好。。！请将其作为答案发布，以获得积分/升级票…！）<代码>401不是例外，它是响应

未经授权的

请求的一个CChalrange。可能存在重复的

 catch (WebException ex)
 {
            HttpWebResponse httpResponse = (HttpWebResponse)ex.Response;
            using (WebResponse response = ex.Response)
            using (Stream data = response.GetResponseStream())
            using (StreamReader reader = new StreamReader(data))
            {
                string errorMessage = reader.ReadToEnd();
            }
 }