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Abot爬虫和visjs
1. 引言
最近接触Abot爬虫也有几天时间了，闲来无事打算从IMDB网站上爬取一些电影数据玩玩。正好美国队长3正在热映，打算爬取漫威近几年的电影并用vis这个JS库呈现下漫威宇宙的相关电影。
Abot是一个开源的C#爬虫，代码非常轻巧。可以参看这篇文章（利用Abot 抓取博客园新闻数据）入门Abot。
Vis 是一个JS的可视化库类似于D3。vis 提供了像Network 网络图的可视化，TimeLine 可视化等等。这里用到了network,只需要给vis传入简单的节点信息，边的信息就可以自动构建一个网络图。
2. 实现
首先从数据开始，得到漫威宇宙所有相关的电影名称，这个数据网上太多了：
从电影名称到IMDB的电影页面其实有个搜索过程，还好电影数目不多，这里偷个懒直接采用IMDB的电影链接作为种子Url
public static List<string> ImdbFeedMovies = new List<string>() { //Iron man 2008 "http://www.imdb.com/title/tt1233205/", //hunk 2008 "http://www.imdb.com/title/tt0800080/", //Iron man 2 2010 "http://www.imdb.com/title/tt1228705/", //Thor 2011 "http://www.imdb.com/title/tt0800369/", //Captain America "http://www.imdb.com/title/tt0458339/", //Averages "http://www.imdb.com/title/tt0848228/", //Iron man 3 "http://www.imdb.com/title/tt1300854/", //thor 2 "http://www.imdb.com/title/tt1981115/", //Captain America 2 "http://www.imdb.com/title/tt1843866/", //Guardians of the Galaxy; "http://www.imdb.com/title/tt2015381/", //Ultron "http://www.imdb.com/title/tt2395427/", //ant-man "http://www.imdb.com/title/tt0478970/", //Civil war "http://www.imdb.com/title/tt3498820/", //Doctor Strange "http://www.imdb.com/title/tt1211837/", //Guardians of the Galaxy 2; "http://www.imdb.com/title/tt3896198/", //Thor 3 "http://www.imdb.com/title/tt3501632/", // Black Panther "http://www.imdb.com/title/tt1825683/", //Avengers: Infinity War - Part I "http://www.imdb.com/title/tt4154756/" };有了种子Url 就可以利用Abot 爬取电影的数据，这里只爬取电影名称，电影图片以及演员。
这里定义一些需要用到的数据结构：
public class MarvellItem { /// <summary> /// http://www.imdb.com/title/tt0800369/ /// </summary> public string ImdbUrl { get; set; } public string Name { get; set; } public string Image { get; set; } } public class ImdbMovie { public string ImdbUrl { get; set; } public string Name { get; set; } public string Image { get; set; } public DateTime Date { get; set; } public List<MarvellItem> Actors { get; set; } } public static readonly Regex MovieRegex = new Regex("http://www.imdb.com/title/tt\\d+", RegexOptions.Compiled);Abot中爬取页面后最主要的处理函数就是PageCrawlCompletedAsync ，这里给出爬取每个电影页面后的complete Callback函数
private ConcurrentDictionary<string, ImdbMovie> movieResult; //爬取到的电影数据 public void Moviecrawler_ProcessPageCrawlCompletedAsync(object sender, PageCrawlCompletedArgs e) { if (MovieRegex.IsMatch(e.CrawledPage.Uri.AbsoluteUri)) { var csTitle = e.CrawledPage.CsQueryDocument.Select(".title_block > .title_bar_wrapper > .titleBar > .title_wrapper > h1"); string title = HtmlData.HtmlDecode(csTitle.Text().Trim()); var datetime = e.CrawledPage.CsQueryDocument.Select( ".title_block > .title_bar_wrapper > .titleBar > .title_wrapper > .subtext > a:last > meta"); var year = datetime.Attr("content").Trim(); var csImg = e.CrawledPage.CsQueryDocument.Select(".poster > a > img"); string image = csImg.Attr("src").Trim(); if (!string.IsNullOrEmpty(image)) { HttpWebRequest webRequest = (HttpWebRequest) WebRequest.Create(image); webRequest.Credentials = CredentialCache.DefaultCredentials; var stream = webRequest.GetResponse().GetResponseStream(); if (stream != null) { Image bitmap = new Bitmap(stream); image = e.CrawledPage.Uri.AbsoluteUri.GetHashCode() + ".jpg"; bitmap.Save(image); } } var csTable = e.CrawledPage.CsQueryDocument.Select("#titleCast > table"); var csTrs = csTable.Select("tr", csTable); List<MarvellItem> actors = new List<MarvellItem>(); foreach (var tr in csTrs) { var csTr = new CsQuery.CQ(tr); var cslink = csTr.Select("td > a", csTr); if (cslink.Any()) { string url = NormUrl(cslink.Attr("href").Trim()); string actorTitle = cslink.Select("img", cslink).Attr("title").Trim(); string actorImage = cslink.Select("img", cslink).Attr("src").Trim(); actors.Add(new MarvellItem() { Name = actorTitle, ImdbUrl = url, Image = actorImage }); } } this.movieResult.TryAdd(e.CrawledPage.Uri.AbsoluteUri, new ImdbMovie() { Name = title, Image = image, Date = DateTime.Parse(year), ImdbUrl = e.CrawledPage.Uri.AbsoluteUri, Actors = actors }); } }该函数的主要功能就是解析电影页面，得到电影名字 电影图片 和 演员信息。这里面还有一个小trick ,由于IMDB的限制，需要把爬到的图片下载下来，否则在生产环境下<img src=http://www.mamicode.com/””/> 图片是无法显示的.
更多这个trick的细节可以参看 关于img 403 forbidden的一些思考
对于所有的电影链接，可以采用Task 并行执行：
Task[] movieTasks = new Task[ImdbFeedMovies.Count]; System.Console.WriteLine("Start crawl Movies"); for (var i = 0; i < ImdbFeedMovies.Count; i++) { var url = ImdbFeedMovies[i]; movieTasks[i] = new Task(() => { System.Console.WriteLine("Start crawl:" + url); var crawler = GetManuallyConfiguredWebCrawler(); ConfigMovieCrawl(crawler); crawler.Crawl(new Uri(url)); System.Console.WriteLine("End crawl:" + url); }); movieTasks[i].Start(); } Task.WaitAll(movieTasks); System.Console.WriteLine("End crawl Movies");结束后我们得到一堆JSON 数据
把它传到前端：
@model List<ImdbMovie><div class="clearfix" style=" position: relative"> <div id="marvel-graph"> </div></div>@section PostScripts{ <script type="text/javascript"> $(function () { var nodes = []; var edges = []; @for (int i = 0; i < Model.Count; i++) { var film = Model[i]; <text> nodes.push({ id: ‘@film.ImdbUrl‘, title: ‘@film.Name‘, borderWidth: 4, shapeProperties: {useBorderWithImage: true}, shape: "image", image: ‘@(string.IsNullOrEmpty(film.Image) ? "" : (film.Image.StartsWith("http") ? film.Image : Href("../../Images/marvel/"+film.Image)))‘, color: { border: ‘#4db6ac‘, background: ‘#009688‘ } }); @if (i != Model.Count - 1) { <text> edges.push({ from: ‘@film.ImdbUrl‘, to: ‘@Model[i+1].ImdbUrl‘, arrows: { to: true }, width: 4, length:360, color: "red" }); </text> } @foreach (var actor in film.Actors) { <text> nodes.push({ id: ‘@film.ImdbUrl‘ + ‘@actor.ImdbUrl‘, title: ‘@actor.Name‘, borderWidth: 4, shapeProperties: { useBorderWithImage: true }, shape: "circularImage", image: ‘@(string.IsNullOrEmpty(actor.Image) ? "" : (actor.Image.StartsWith("http") ? actor.Image : Href("../../Images/marvel/"+actor.Image)))‘, }); edges.push({ from: ‘@film.ImdbUrl‘, to: ‘@film.ImdbUrl‘ + ‘@actor.ImdbUrl‘, arrows: { to: true } }); </text> } </text> } var container = document.getElementById("marvel-graph"); var visNodes = new vis.DataSet(nodes); var data = http://www.mamicode.com/{>vis network 主要就是 new Network(container, data, options); 传入节点 和 边即可。
最终的效果如图：
Abot爬虫和visjs
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