如何使用Html Agility Pack超时请求

.net asp.net-mvc-3 c# html-agility-pack timeout

我正在向当前处于脱机状态的远程Web服务器发出请求(故意)。

我想找出超时请求的最佳方法。基本上,如果请求的运行时间超过“X”毫秒,则退出请求并返回null响应。

目前网络请求只是坐在那里等待响应.....

我怎样才能最好地解决这个问题?

这是一个当前的代码片段

    public JsonpResult About(string HomePageUrl)
    {
        Models.Pocos.About about = null;
        if (HomePageUrl.RemoteFileExists())
        {
            // Using the Html Agility Pack, we want to extract only the
            // appropriate data from the remote page.
            HtmlWeb hw = new HtmlWeb();
            HtmlDocument doc = hw.Load(HomePageUrl);
            HtmlNode node = doc.DocumentNode.SelectSingleNode("//div[@class='wrapper1-border']");

            if (node != null)
            { 
                about = new Models.Pocos.About { html = node.InnerHtml };
            }
                //todo: look into whether this else statement is necessary
            else 
            {
                about = null;
            }
        }

        return this.Jsonp(about);
    }

一般承认的答案

我不得不对我最初发布的代码做一个小调整

    public JsonpResult About(string HomePageUrl)
    {
        Models.Pocos.About about = null;
        // ************* CHANGE HERE - added "timeout in milliseconds" to RemoteFileExists extension method.
        if (HomePageUrl.RemoteFileExists(1000))
        {
            // Using the Html Agility Pack, we want to extract only the
            // appropriate data from the remote page.
            HtmlWeb hw = new HtmlWeb();
            HtmlDocument doc = hw.Load(HomePageUrl);
            HtmlNode node = doc.DocumentNode.SelectSingleNode("//div[@class='wrapper1-border']");

            if (node != null)
            { 
                about = new Models.Pocos.About { html = node.InnerHtml };
            }
                //todo: look into whether this else statement is necessary
            else 
            {
                about = null;
            }
        }

        return this.Jsonp(about);
    }

然后我修改了我的RemoteFileExists扩展方法以使其超时

    public static bool RemoteFileExists(this string url, int timeout)
    {
        try
        {
            //Creating the HttpWebRequest
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;

            // ************ ADDED HERE
            // timeout the request after x milliseconds
            request.Timeout = timeout;
            // ************

            //Setting the Request method HEAD, you can also use GET too.
            request.Method = "HEAD";
            //Getting the Web Response.
            HttpWebResponse response = request.GetResponse() as HttpWebResponse;
            //Returns TRUE if the Status code == 200
            return (response.StatusCode == HttpStatusCode.OK);
        }
        catch
        {
            //Any exception will returns false.
            return false;
        }
    }

在这种方法中,如果我的超时在RemoteFileExists可以确定标头响应之前RemoteFileExists ,那么我的bool将返回false。


热门答案

Html Agility Pack是开源的。这就是为什么你可以修改源自己。首先将此代码添加到类HtmlWeb

private int _timeout = 20000;

public int Timeout 
    { 
        get { return _timeout; } 
        set
        {
            if (_timeout < 1) 
                throw new ArgumentException("Timeout must be greater then zero.");
            _timeout = value;
        }
    }

然后找到这个方法

private HttpStatusCode Get(Uri uri, string method, string path, HtmlDocument doc, IWebProxy proxy, ICredentials creds)

并修改它:

req = WebRequest.Create(uri) as HttpWebRequest;
req.Method = method;
req.UserAgent = UserAgent;
req.Timeout = Timeout; //add this

或类似的东西:

htmlWeb.PreRequest = request =>
            {
                request.Timeout = 15000;
                return true;
            };


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这个KB合法吗? 是的,了解原因
许可下: CC-BY-SA with attribution
不隶属于 Stack Overflow
这个KB合法吗? 是的,了解原因