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，我在页面加载时注册了一个事件监听器，但是当我调试它时，它在设置相同的事件后退出，而不是在页面“加载”之后实际执行我想要它做的事情。

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，它只能到达使用方法使用url参数导航浏览器实例...

Answer 1

WebBrowser要求您的程序泵出消息循环。否则它不会发射它的事件。这通常是对使用单线程COM组件的任何程序的要求。或者用更易理解的术语来说：你不能让程序忙于从控制台读取数据，同时解雇像DocumentCompleted这样的事件。一个线程一次只能做一件事。您可以通过编写Winforms应用程序或使用Application.Run（）自行启动消息循环。使用消息循环，线程可以一次执行多个操作。但这确实需要与您现在编写的代码完全不同的代码，您仍然无法使用Console.ReadLine（），而是使用TextBox代替。

您可以通过在单独的线程中运行浏览器来拯救您拥有的内容，您将在this answer中找到所需的代码。

WebBrowser无法访问DocumentCompleted事件

1 个答案: