主要思想：通过后台WebView载入指定网页，再提取出WebView中的内容

关键代码：

var html = await webView.InvokeScriptAsync("eval", new string[] { "document.documentElement.outerHTML;" });

有一个很简单的思路，

订阅WebView NavigationCompleted事件，然后让Navigate到指定的网址，发生事件时执行这行代码

 

 

除此之外，这里还有一个异步的方法，用到了TaskCompletionSource这个东西

首先，创建一个TaskCompletionSource：

TaskCompletionSource
     
       completionSource = new TaskCompletionSource
      
       ();
      
     

因为返回的东西是string（html），所以泛型T设置成string

然后使用lambda的形式订阅Navigation事件：

1 webView.NavigationCompleted += async (sender, args) => 2 { 3     if (args.Uri != uri) 4         return; 5     await Task.Delay(200); 6     var html = await sender.InvokeScriptAsync("eval", new string[] { "document.documentElement.outerHTML;" }); 7     webView.NavigateToString(""); 8     webView = null; 9     completionSource.SetResult(html);10 };

Line5的延迟200ms，是为了Navigation完成之后再给页面里的其他一些元素（比如一些js脚本）一些加载的时间（讲道理订阅事件里也应该写一个的）

Line7的导航到空是为了防止WebView里的东西继续运行从而导致一些灵异事件（尤其是一些带视频的网页，咳咳）

Line9，给Task设置个Result，await就会结束

 

最后：

1 return completionSource.Task;

 

封装成类：

public class WebHelper    {        public class WebLoadedArgs:EventArgs        {            public bool Success { get; private set; }            public WebErrorStatus WebErrorStatus { get; private set; }            public string Html { get; private set; }            public WebLoadedArgs(WebErrorStatus webErrorStatus)            {                WebErrorStatus = webErrorStatus;                Success = false;            }            public WebLoadedArgs(string Html,WebErrorStatus webErrorStatus)            {                this.Html = Html;                WebErrorStatus = webErrorStatus;                Success = true;            }        }        public string Url { get; private set; }        public event EventHandler
     
       WebLoaded;        private WebView webView;        public WebHelper(string Url)        {            this.Url = Url;            webView = new WebView(WebViewExecutionMode.SeparateThread);            webView.Navigate(new Uri(Url));            webView.NavigationCompleted += WebView_NavigationCompleted;            webView.NavigationFailed += WebView_NavigationFailed;        }        private void WebView_NavigationFailed(object sender, WebViewNavigationFailedEventArgs e)        {            WebLoaded(this, new WebLoadedArgs(e.WebErrorStatus));        }        private async void WebView_NavigationCompleted(WebView sender, WebViewNavigationCompletedEventArgs args)        {                        var html = await sender.InvokeScriptAsync("eval", new string[] { "document.documentElement.outerHTML;" });            webView = null;            WebLoaded(this, new WebLoadedArgs(html,args.WebErrorStatus));        }        /// 
      
        /// 异步实现获取Web内容        /// 
        /// 
      网址        /// 
      超时时间        /// 
      
       Web的Html内容
              public static Task
      
        LoadWebAsync(string Url,int Timeout)        {            return LoadWebAsync(Url, "", Timeout);        }        /// 
       
        /// 异步实现获取Web内容        /// 
        /// 
       网址        /// 
       Header[Referer]，用以解决一些盗链效验        /// 
       超时时间        /// 
       
        Web的Html内容
               public static Task
       
         LoadWebAsync(string Url,string Referer, int TimeOut)        {                        WebView webView = new WebView(WebViewExecutionMode.SeparateThread);            Uri uri = new Uri(Url);            HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Get, uri);            requestMessage.Headers.Add("Referer", Referer);            webView.NavigateWithHttpRequestMessage(requestMessage);            TaskCompletionSource
        
          completionSource = new TaskCompletionSource
         
          ();            webView.NavigationCompleted += async (sender, args) =>            {                if (args.Uri != uri)                    return;                await Task.Delay(200);                var html = await sender.InvokeScriptAsync("eval", new string[] { "document.documentElement.outerHTML;" });                webView.NavigateToString("");                webView = null;                completionSource.SetResult(html);            };            webView.NavigationFailed += (sender, args) =>            {                webView = null;                completionSource.SetException(new WebException("", (WebExceptionStatus)args.WebErrorStatus));            };            DispatcherTimer timer = new DispatcherTimer();            timer.Interval = TimeSpan.FromSeconds(TimeOut);            timer.Tick += (sender, args) =>            {                timer = null;                webView.NavigateToString("");                webView = null;                completionSource.SetException(new TimeoutException());            };            timer.Start();            return completionSource.Task;        }    }
         
        
       
      
     

 

使用方法：

（事件订阅的方式）

WebHelper webHelper = new WebHelper("http://www.baidu.com/");        webHelper.WebLoaded += WebHelper_WebLoaded;        private void WebHelper_WebLoaded(object sender, WebHelper.WebLoadedArgs e)        {            if(e.Success)            {                var html = e.Html;            }        }

 

（异步的方式）

var html = await WebHelper.LoadWebAsync("http://www.baidu.com", 120);