Question

我收到此错误

未处理的类型＆＃39; System.InvalidCastException＆＃39;发生了在WindowsFormsApplication2.exe中附加信息：无法强制转换类型对象System.Windows.Forms.Button＆＃39;输入＆＃39; System.Windows.Forms.WebBrowser＆＃39;

继承代码

private void button6_Click(object sender, EventArgs e)
    {
        int counter = 0;
        string line;
        System.IO.StreamReader file = new System.IO.StreamReader("test.txt");

        while ((line = file.ReadLine()) != null)
        {
            textBox6.Text = "";
            textBox5.Text = "";
            textBox4.Text = "";
            textBox2.Text = "";

            textBox6.Text = counter.ToString();
            string link = line.ToString() ;
            textBox5.Text = link;
         //   WebRequest req = HttpWebRequest.Create(link);
         //   req.Method = "GET";


            WebBrowser wb = (WebBrowser)sender;
            wb.Navigate(link);
            wb.Document.ExecCommand("SelectAll", false, null);

            wb.Document.ExecCommand("Copy", false, null);

            string html = wb.DocumentText;
            textBox1.Text = html;
            textBox2.Text = Clipboard.GetText();
            textBox3.Text = "done";

            if (html.Contains("<title>"))
            {
                string title = ExtractFromString(html, "<title>", "</title>");
                textBox4.Text = title;
            }
            else
            {
                string title = ExtractFromString(html, "<TITLE>", "</TITLE>");
                textBox4.Text = title;
            }

            wb.Dispose();
            createpage(textBox4.Text, textBox2.Text, textBox5.Text);


            counter++;
        }
        file.Close();
        textBox3.Text = counter.ToString();


    }
  }
}

Answer 1

sender几乎肯定是Button（来自函数名称＆＃34; button6_click＆＃34;）。

WebBrowser wb = (WebBrowser)sender;

Button无法投放到WebBrowser（原因很明显）。在这种情况下，您可能需要按名称引用WebBrowser控件。

WebBrowser wb = someExistingNamedWebBrowser;

Answer 2

你的问题在于这一行：

WebBrowser wb = (WebBrowser)sender;

因为这是按钮点击事件，sender将是Button。试试这个：

WebBrowser wb = new WebBrowser();

或者，如果表单上已有表格，请参考：

WebBrowser wb = webBrowser1;

无法转换为按钮

2 个答案: