Question

我在c＃代码中进行了很多web api调用。我不知道如何捕捉错误。假设，互联网连接不起作用，那么我的代码显示运行时错误。如何正确地将它们放入try catch块中，一般规则是什么。我找到的所有文章都是关于如何丢弃错误和错误信息示例API调用：

 WebResponse webResponse = webRequest.GetResponse();
 string res = webResponse.ToString();

另外

using (var client = new HttpClient())
      client.BaseAddress = new Uri(CairoBaseUrl);
      var getStringTask = client.GetStringAsync(requestUrl);
      response = await getStringTask;

和

HttpResponseMessage response = await client.PostAsync(
                url,requestContent);

Answer 1

如果您正在调用asp.net web api，我建议您使用为此目的而完成的HttpClient

 try    
  {
     HttpResponseMessage response = await client.GetAsync("http://www.contoso.com/");
     response.EnsureSuccessStatusCode();
     string responseBody = await response.Content.ReadAsStringAsync();
     // Above three lines can be replaced with new helper method below 
     // string responseBody = await client.GetStringAsync(uri);

     Console.WriteLine(responseBody);
  }  
  catch(HttpRequestException e)
  {
     Console.WriteLine("\nException Caught!");  
     Console.WriteLine("Message :{0} ",e.Message);
  }

这是MSDN如何使用http客户端

处理异常的示例

在你的例子中你有

using (var client = new HttpClient())
      client.BaseAddress = new Uri(CairoBaseUrl);
      var getStringTask = client.GetStringAsync(requestUrl);
      response = await getStringTask;

但它不会工作，因为await运算符只能用于标记为异步的方法，所以它应该是

  var getStringTask = await client.GetStringAsync(requestUrl);

在进行web api调用时捕获异常

1 个答案: