如何使用HtmlAgilityPack检查它是否是404错误页面(页面不存在)

Question

在这里,我试图阅读网址并在页面中获取图像.我需要排除页面,如果它是404并停止从404错误页面获取图像.如何使用HtmlAgilityPack？这是我的代码

var document = new HtmlWeb().Load(completeurl);
var urls = document.DocumentNode.Descendants("img")
          .Select(e => e.GetAttributeValue("src", null))
          .Where(s => !String.IsNullOrEmpty(s)).ToList();

Answer 1

您需要PostRequestHandler在HtmlWeb实例上注册一个事件,它将在每个下载的文档之后引发,您将可以访问该HttpWebResponse对象.它有一个属性StatusCode.

 HtmlWeb web = new HtmlWeb();
 HttpStatusCode statusCode = HttpStatusCode.OK;
 web.PostRequestHandler += (request, response) =>
 {
     if (response != null)
     {
         statusCode = response.StatusCode;
     }
 }

 var doc = web.Load(completeUrl)
 if (statusCode == HttpStatusCode.OK)
 {
     // received a read document
 }

看一下GutHub上HtmlAgilityPack的代码,它更简单,HtmlWeb有一个属性StatusCode设置值:

var web = new HtmlWeb();
var document = web.Load(completeurl);

if (web.StatusCode == HttpStatusCode.OK)
{
    var urls = document.DocumentNode.Descendants("img")
          .Select(e => e.GetAttributeValue("src", null))
          .Where(s => !String.IsNullOrEmpty(s)).ToList();
}

更新

AgilityPack API已有更新.诀窍仍然是一样的:

var htmlWeb = new HtmlWeb();
var lastStatusCode = HttpStatusCode.OK;

htmlWeb.PostResponse = (request, response) =>
{
    if (response != null)
    {
        lastStatusCode = response.StatusCode;
    }
};