Microsoft.mshtml VS HtmlAgilityPack

爬虫清洗数据时除了正则表达式有时候解析HTML文档能更快更方便的拿到数据

解析HTML的库除了微软自带的Microsoft.mshtml 之外比较受欢迎的是HtmlAgilityPack，之前一直用的是前者，后面发现他俩差别还是蛮大的；

①效率：

 ②代码

Microsoft.mshtml 

static List<string> GetHouseLinks2(string strDoc)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();
            var doc = GetHTMLDocument(strDoc);
            var list = new List<string>();

            var anchors = doc.getElementsByTagName("a");

            foreach (HTMLAnchorElement anchor in anchors)
            {
                var href = ((string)anchor.getAttribute("href"));
                if (href != null)
                {
                    if (href.Contains("property-detail"))
                    {
                        list.Add(href);
                        Console.WriteLine(href);
                    }
                }
            }

            Console.WriteLine(list.Count);
            sw.Stop();
            TimeSpan ts2 = sw.Elapsed;
            Console.WriteLine("MSHtml总共花费{0}ms.", ts2.TotalMilliseconds);
            return list;
        }

public static HTMLDocument GetHTMLDocument(string html)
        {
            var doc = new HTMLDocument();

            var doc2 = doc as IHTMLDocument2;
            doc2.designMode = "on";
            doc2.write(new object[] { html });

            doc = (HTMLDocument)doc2;

            return doc;
        }

HtmlAgilityPack：

static List<string> GetHouseLinks(string strDoc)
        {
            Stopwatch sw = new Stopwatch();
            sw.Start();

            HtmlDocument htmlDoc = new HtmlDocument();
            htmlDoc.LoadHtml(strDoc);//string转HtmlDocument

            //获取属性值
            var houseLinks = new List<string>();
            string url = "https://www.pproperties.com.hk/tc/property-search-result";

            HtmlNodeCollection linkNodes = htmlDoc.DocumentNode.SelectNodes(@"//a[@href]");
            foreach (var link in linkNodes)
            {
                string href = link.Attributes["href"].Value;
                if (href.Contains("detail"))
                {
                    houseLinks.Add(href);
                    Console.WriteLine(href);
                }
            }
            Console.WriteLine(houseLinks.Count);

            
            sw.Stop();
            TimeSpan ts2 = sw.Elapsed;
            Console.WriteLine("HtmlAgilityPack总共花费{0}ms.", ts2.TotalMilliseconds);
            return houseLinks;
        }

传入的strDoc是接响应的Html字符串；后者string转HTML文档只需要两句代码方可实现；

而最大的区别是HtmlAgilityPack可以用XPath获取标签路径属性，非常方便，而Microsoft.mshtml只能一层一层获取或者只能一次性获取某种类型的标签如下获取h1标签下的span标签：

//标题
                var heads = doc.getElementsByTagName("h1");
                foreach (HTMLHeadElement h in heads)
                {
                    if (!string.IsNullOrEmpty(h.innerText))
                    {
                        var spanElement = h.getElementsByTagName("span")?.item(0) as HTMLSpanElement;
                        property.District = spanElement?.innerText?.Trim() ?? string.Empty;
                        var ename = h.innerText.Split(property.District[0]);
                        if (ename.Length > 0)
                            property.EstateName = ename[0];
                        Msg = "  抓取" + "  [" + property.District + "  " + property.EstateName + "]";
                        Console.WriteLine(Msg);
                        break;
                    }
                }

而XPath仅需"//h1/span"即可