如何捕捉异常？ [英] How to catch exception?

问题描述

我试图调用API，并检查它的反应，但是当过一些错误的值传递停止该程序。我想在请求和响应，但不知道如何在函数中加上例外。

I am trying to call api and check its response, but when ever some wrong value is passed it stops the program. I want to add exception during request and response but not sure how to write in function.

这是我怎么叫我的REST调用

This is how i call my REST call

public dynamic APICalls(JObject ljson, string endpoints, string method)
        {
            var httpReq = (HttpWebRequest)HttprequestObject(endpoints, method);
            using (var streamWriter = new StreamWriter(httpReq.GetRequestStream()))
            {
                streamWriter.Write(ljson);
                streamWriter.Flush();
                streamWriter.Close();
            }
            var httpResponse = (HttpWebResponse)httpReq.GetResponse();
            var result = "";
            using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
            {
                result = streamReader.ReadToEnd();
            }
            return result;
            //return "Success";
            //not sure what to return 
            //here i have to add sql server code to enter into database
        }

这是$ C $下要求

public dynamic HttprequestObject(string endpoints, string method)
        {
            string url = Settings.API_TEST_VALUE + endpoints;
            var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
            httpWebRequest.ContentType = "application/json";
            httpWebRequest.Method = method;
            return httpWebRequest;
        }

和之前的要求，我想捕捉异常后，正确的反应的权利。

And right before request and right after response i want to catch exception.

在这一点上我要赶异常

 var httpResponse = (HttpWebResponse)httpReq.GetResponse();

如果有人给我暗示如何捕捉它停止程序之前。

If some one gives me hint how to catch that before it stops program.

有400，401,402错误，如果事情是错的API发送JSON

There are 400, 401,402 errors, if something is wrong API sends json

例如，在创建用户： - 电子邮件ID已经存在

For instance, while creating user :-- Email id already exists

但是，这点停止JSON和终止程序。

But that points stops json and stops program..

使用尝试捕捉它会停止程序，我希望它运行，并希望接收resposne。

Using try catch it will stop program, I want it to run and want to receive resposne.

其实，API将发送错误。 例如，状态会; --- 401未授权 和resposnse将

Actually, API will send error . For instance, status will be ;---401 UNAUTHORIZED and resposnse will be

{ "reason": "Email already registered.", "success": false } 

我改变了我的code和

I am changed my code and

   HttpWebResponse httpResponse; 
            try
            {
               //HttpWebResponse myHttpWebResponse = (HttpWebResponse)httpReq.GetResponse();
               httpResponse = (HttpWebResponse)httpReq.GetResponse();
               //myHttpWebResponse.Close();

               using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
               {
                   result = streamReader.ReadToEnd();
               }
            }
            catch (WebException e)
            {
                Console.WriteLine("This program is expected to throw WebException on successful run." +
                                    "\n\nException Message :" + e.Message);
                if (e.Status == WebExceptionStatus.ProtocolError)
                {
                    Console.WriteLine("Status Code : {0}", ((HttpWebResponse)e.Response).StatusCode);
                    Console.WriteLine("Status Description : {0}", ((HttpWebResponse)e.Response).StatusDescription);
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

            return result;
            //return "Success";
            //not sure what to return 
            //here i have to add sql server code to enter into database
        }

这是新的code，但我很老JSON作为返回值，所以我可以显示特定的错误。 对于下面的Json我应该怎么写呢？

This is the new code, but I m not getting Json as return value, So i can show specific error. For below Json what should I write?

{理由：电子邮件已经注册，成功：假}

{ "reason": "Email already registered.", "success": false }

请我为新的C＃，如果事情是不明确，请修改或问的问题？ 谢谢

please I m new to c# and if something is not clear please modify or ask question? thank you

推荐答案

您正在寻找所谓的的 的try-catch 语句：

What you're looking for is called a try-catch statement:

try
{
     var httpResponse = (HttpWebResponse)httpReq.GetResponse();
}
catch (WebException e)
{
    // Here is where you handle the exception.
}

使用 WebException 如抓类型语句的意思是特定类型的唯一例外的会被抓住。

Using WebException as the type in the catch statement means only exceptions of that particular type will be caught.

在的情况下发生异常时，电子变量将包含异常的详细信息，如从内这三个异常，内部异常封装的方法传递消息。

In case an exception occurs, the e variable will contain exception details, such as a message passed from the method which three the exception and any inner exceptions encapsulated inside.

这篇关于如何捕捉异常？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！