返回任务<IHttpActionResult>方法的JSON错误消息

Question

我创建了一个ASP.NET Web API，它将调用java web服务并在JSON中显示一些结果。当java web服务未运行时，我收到错误消息：

{“Message”：“发生错误。”，“ExceptionMessage”：“方法或操作未实现。”， C：\ Users \ attsuap1 \ Desktop \ Server Project \ ApiClientJavaWebService \ ApiClientJavaWebService \ Models \ RestfulClient.cs中的ApiClientJavaWebService.Models.RestfulClient.InternalServerError（异常例外）中的“ExceptionType”：“System.NotImplementedException”，“StackTrace”在C：\ Users \ attsuap1 \ Desktop \ Server Project \ ApiClientJavaWebService \ ApiClientJavaWebService \ Models \ RestfulClient.cs中的ApiClientJavaWebService.Models.RestfulClient.d__3.MoveNext（）中的第43行\ r \ n：第36行\ r \ n ---从抛出异常的上一个位置结束堆栈跟踪--- System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）中的\ r \ n \ System.Runtim中的\ r \ n e.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n在System.Runtime.CompilerServices.TaskAwaiter 1.GetResult（）\ r \ n在ApiClientJavaWebService.Controllers.AdditionController.d__1.MoveNext（）在C：\ Users \ attsuap1 \ Desktop \ Server Project \ ApiClientJavaWebService \ ApiClientJavaWebService \ Controllers \ AdditionController.cs：第20行\ r \ n ---从以前位置抛出异常的堆栈跟踪结束--- \ r \ n在System.Runtime.CompilerServices .TaskAwaiter.ThrowForNonSuccess（任务任务）\ r \ n在System.Threading.Tasks.TaskHelpersExtensions.d__3`1.MoveNext（）\ r \ n System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n ---从以前位置抛出异常的堆栈跟踪结束---在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）上的\ r \ n在System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n在System.Web.Http.Controllers.ApiControl lerActionInvoker.d__0.MoveNext（）\ r \ n ---从之前的位置抛出异常的堆栈跟踪结束--- \ r \ n在System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\ r \ n System.Web.Http.Controllers.ActionFilterResult.d__2.MoveNext（）\ r \ n下System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n ---以前位置的堆栈跟踪结束，其中异常在System.Web的System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）\ r \ n处，System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）\ r \ n处抛出--- \ r \ n。 Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext（）“}

我要如何改变这种去显示为{"The server is not running."}错误信息？

这里是我的代码：

AdditionClient.cs

public class RestfulClient 
{ 
    private static HttpClient client; 
    private static string BASE_URL = "http://localhost:8080/"; 

    static RestfulClient() 
    { 
     client = new HttpClient(); 
     client.BaseAddress = new Uri(BASE_URL); 
     client.DefaultRequestHeaders.Accept.Add(
      new MediaTypeWithQualityHeaderValue("application/json")); 
    } 

    public async Task<string> addition(int firstNumber, int secondNumber) 
    { 

     try 
     { 
      var endpoint = string.Format("addition/{0}/{1}", firstNumber, secondNumber); 
      var response = await client.GetAsync(endpoint); 
      return await response.Content.ReadAsStringAsync(); 
     } 

     catch (Exception e) 
     { 

     } 

     return null; 
    } 
} 

AdditionController.cs

public class AdditionController : ApiController 
{ 
    private RestfulClient restfulClient = new RestfulClient(); 
    public async Task<IHttpActionResult> Get(int firstNumber, int secondNumber) 
    { 
     var result = await restfulClient.addition(firstNumber, secondNumber); 
     var resultDTO = JsonConvert.DeserializeObject<Temp>(result); 
     return Json(resultDTO); 
    } 
} 

有人请你帮帮我。提前谢谢你。

Answer 1

我已经达到了我想要的。我意识到try catch方法应该在控制器类中而不是AdditionClient.cs类中。

这里是我的编辑类：

AdditionClient.cs

public class RestfulClient 
{ 
    private static HttpClient client; 
    private static string BASE_URL = "http://localhost:8080/"; 

    static RestfulClient() 
    { 
     client = new HttpClient(); 
     client.BaseAddress = new Uri(BASE_URL); 
     client.DefaultRequestHeaders.Accept.Add(
      new MediaTypeWithQualityHeaderValue("application/json")); 
    } 

    public async Task<string> addition(int firstNumber, int secondNumber) 
    { 
      var endpoint = string.Format("addition/{0}/{1}", firstNumber, secondNumber); 
      var response = await client.GetAsync(endpoint); 
      return await response.Content.ReadAsStringAsync(); 
    } 
} 

AdditionController.cs（聚焦在尝试捕捉部分）

 try 
     { 
      var result = await restfulClient.addition(firstNumber, secondNumber); 
      var resultDTO = JsonConvert.DeserializeObject<Temp>(result); 
      return Json(resultDTO); 
     } 

     catch (Exception e) 
     { 
      var result = @"Server is down"; 
      return Ok(new { ErrorMessage = result }); 
     } 

，这将是结果当服务器没有运行时，在浏览器上显示的是{"ErrorMessage":"Server is down"}。

Answer 2

我想，你不能管理抛出你想要拉动数据的服务器的异常消息。那么，为什么不过滤这个异常呢？

 try 
     { 
      var endpoint = string.Format("addition/{0}/{1}", firstNumber, secondNumber); 
      var response = await client.GetAsync(endpoint); 
      return await response.Content.ReadAsStringAsync(); 
     } 

     catch (Exception e) 
     { 
      if (e.InnerException.Message == "The method or operation is not implemented") 
      { 
       //Do something 
      } 
     }