c# - WebBrowser 没有到达 DocumentCompleted 事件

Question

我是 c# 的新手，我正在尝试构建一个登录网站并返回其源代码的程序。问题是，我为页面加载时注册了一个事件监听器，但是当我调试它时，它在设置相同事件后退出，实际上并没有在页面“加载”后执行我希望它执行的操作。

这是来源-

using System;
using System.Windows.Forms;

namespace WIN
{
    class Program
    {
        string url = -snip-;
        string username = -snip-;
        string password = -snip-;
        string task = -snip-;
        string action = -snip-;
        string timezone = -snip-;

        private void Login()
        {
            Console.WriteLine("Started.");
            Console.ReadLine();
            Console.WriteLine("Declaring WebBrowser instance browser...");
            WebBrowser browser = new WebBrowser();
            Console.WriteLine("Done.");
            Console.ReadLine();
            Console.WriteLine("Registering an event for when the page finishes loading...");
            browser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(pageLoaded);
            Console.WriteLine("Done.");
            Console.ReadLine();
            Console.WriteLine("Using method Navigate of browser instance with url parameter...");
            browser.Navigate(url);
            Console.WriteLine("Done.");
            Console.ReadLine();

        }

        private void pageLoaded(object sender, WebBrowserDocumentCompletedEventArgs e)
        {
            Console.WriteLine("Declaring WebBrowser instance browser as sender...");
            WebBrowser browser = sender as WebBrowser;
            Console.WriteLine("Done.");
            Console.ReadLine();
            string response = browser.DocumentText;

            Console.WriteLine("Searching for authenticity token...");
            // looks in the page source to find the authenticity token.
            // could also use regular expressions here.
            int index = response.IndexOf("authenticity_token");
            int startIndex = index + 41;
            string authenticityToken = response.Substring(startIndex, 40);
            Console.WriteLine("Found authenticity token.");

            Console.WriteLine("Unregistering first event handler...");
            // unregisters the first event handler
            // adds a second event handler
            browser.DocumentCompleted -= new WebBrowserDocumentCompletedEventHandler(pageLoaded);
            Console.WriteLine("Done.");
            Console.WriteLine("Adding second event handler...");
            browser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(pageLoaded2);
            Console.WriteLine("Done.");
            Console.Read();

            Console.WriteLine("Formatting data to be posted to server...");
            string postData = string.Format("_user={0}&_pass={1}&authenticity_token={2}&_task{3}&_action{4}&_timezone{5}", username, password, authenticityToken, task, action, timezone);
            Console.WriteLine("Done.");
            Console.Read();

            Console.WriteLine("Declaring ASCIIEncoding instance enc...");
            System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding();
            Console.WriteLine("Done.");
            Console.Read();

            //  we are encoding the postData to a byte array
            Console.WriteLine("Encoding postData to a byte array...");
            browser.Navigate(url, "", enc.GetBytes(postData), "Content-Type: application/x-www-form-urlencoded\r\n");
            Console.WriteLine("Done..");
            Console.Read();

        }

        [STAThread]
        static void Main(string[] args)
        {
            Program p = new Program();
            p.Login();
        }
    }
}

从所有这些控制台输出中，它只会到达使用方法 Navigate of browser instance with url parameter...

Answer 1

WebBrowser 要求您的程序提供一个消息循环。否则它不会触发事件。这通常是任何使用单线程 COM 组件的程序的要求。或者用更易于理解的术语来说:您不能让程序忙于从控制台读取数据，同时触发 DocumentCompleted 等事件。一个线程一次只能做一件事。您可以通过编写一个 Winforms 应用程序或使用 Application.Run() 自己启动一个来泵送消息循环。使用消息循环，一个线程可以一次做不止一件事。但这确实需要与您现在编写的代码截然不同的代码，您仍然不能使用 Console.ReadLine()，而是使用 TextBox。

您可以通过在单独的线程中运行浏览器来挽救您所拥有的，您将在 this answer 中找到您需要的代码.