Question

此代码必须根据页码查找有效页面。这应该实现逻辑 - 如果具有地址http://hostname/page/x的页面返回了OK状态，则url有效，如果响应状态为NotFound，则url无效。我想在if语句中处理HttpStatusCode，但它总是被try / catch块捕获。

    public void GetAllLinks()
            {
                const string baselink = "http://buzzon.khaleejtimes.com/ad-category/real-estate/page/";
                //Check if OK status answer from server, page link is valid
                for (int i = 1; i < 10000; i++)
                {
                    var url = baselink + i;
                    if (LinkExist(url) != true)
                    {
                      try {
                        HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);
                        // Sends the HttpWebRequest and waits for a response.
                        HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 
                        if (myHttpWebResponse.StatusCode == HttpStatusCode.NotFound)
                        {  
                            //Exit loop if status 404.  
                            break;
                        }
                        WriteUrl(url);
                        myHttpWebResponse.Close();
                  }
                  catch (Exception ex) {
                     throw new Exception(ex.Message);
                   } 
                }
                ParsePages();
        }

Answer 1

试试这个

 public string GetAllLinks()
            {
                const string baselink = "http://buzzon.khaleejtimes.com/ad-category/real-estate/page/";
                //Check if OK status answer from server, page link is valid
                for (int i = 1; i < 10000; i++)
                {
                    var url = baselink + i;
                    if (LinkExist(url) != true)
                    {
                      try 
                      {
                        HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);
                        // Sends the HttpWebRequest and waits for a response.
                        HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 
                      using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                      {
                        if (HttpStatusCode.OK == response.StatusCode)
                        {                           
                          WriteUrl(url);
                          myHttpWebResponse.Close();
                        }
                        else
                           break;
                     }
                  }
                  catch (Exception wex) 
                  {
                     string pageContent = new StreamReader(wex.Response.GetResponseStream()).ReadToEnd().ToString();
                     return pageContent;
                   } 
                }
                ParsePages();
                return "Response Established";
        }

Answer 2

try adding a null check ..

HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create(url);
// Sends the HttpWebRequest and waits for a response.
var temp = myHttpWebRequest.GetResponse();

if (temp == null)
{
         //break code
}
HttpWebResponse myHttpWebResponse = (HttpWebResponse) temp;

Answer 3

好吧，如果有人提供更好的解决方案，我会很高兴，但现在这个解决了：

                    catch (WebException ex)
                    {
                        var resp = (HttpWebResponse) ex.Response;
                        if (resp.StatusCode == HttpStatusCode.NotFound)
                        break;
                    }

我不喜欢这个解决方案，因为它并不美丽。所以如果有人有更好的想法 - 欢迎你。

在if语句中处理HttpStatusCode，而不是try / catch

3 个答案: