asp.net在打开弹出窗口之前检查URL是否存在 [英] asp.net check if url exists before opening popup

问题描述

当前，我在ButtonClick上运行以下代码:

Currently I have the following code that is run on ButtonClick:

Page.ClientScript.RegisterStartupScript(this.GetType(), "OpenWindow", 
"window.open('" + DocumentData.Tables[0].Rows[0]["WebAddress"].ToString() 
                + "','_blank');", true);

它会打开一个弹出窗口，其中包含来自数据库的给定链接(通常是指向文档，图像或视频的链接).但是我需要稍微修改一下代码，而且我不知道应该使用哪种方法:

It opens popup window with given link from DataBase (usually it is a link to document or image or video). But I need to modify code a bit and I do not know which methods should I use:

1)我需要检查url是否确实存在(如果URL响应)，如果不存在，请不要打开弹出窗口，而是显示一些消息.在这里我不知道如何检查网址是否存在?例如，如果url类似于www.thesitedoesntexists.com，则不要加载弹出窗口.

1) I need to check if url really exists (if URL is responsive) and if not do not open popup, but show some message. Here I do not know how to check if Url exists? For example, if url is something like www.thesitedoesntexists.com then Do not load popup.

2)如果url的格式为www.yahoo.com而不是 http://www.yahoo.com 或 https://someurl.com ，则以上操作无效.

2) If url is in format www.yahoo.com instead of http://www.yahoo.com or https://someurl.com then above doesn't work.

如果我的Web应用程序是 www.myapplication.com ，则在上述情况下，系统将打开URL www.myapplication.com/www.yahoo.com 而不是www.yahoo.com .怎么处理呢?这可能与问题#1相关.这是主要问题.

If my web application is www.myapplication.com then in above scenario system opens url www.myapplication.com/www.yahoo.com instead of www.yahoo.com. How to deal with it? It could be somehow related with question #1. And this is the main problem.

推荐答案

以下代码(未经测试)应完成以下任务:

The following code (untested) should accomplish these tasks:

1. 将验证网址是否已定义
2. 将确保使用http://或https://
3. 将通过HttpRequest验证URL是否存在
4. 将显示加载了URL的弹出窗口，或者如果URL未定义或不存在，则显示警告警报.

按钮点击处理程序代码:

Button click handler code:

string url = DocumentData.Tables[0].Rows[0]["WebAddress"].ToString();
string script;

if (!string.IsNullOrEmpty(url))
{
    // prepend http to url if it isn't there.
    if(!url.ToLower().StartsWith("http://") || !url.ToLower().StartsWith("https://"))
    {
        url = "http://" + url;
    }

    // verify URL exists:
    if (UrlExists(url))
    {
        script = "window.open('" + url  + "','_blank');";   
    }
    else
    {
        script = "alert('URL does not exist')";
    }
}
else
{
    script = "alert('No URL specified!')";
}

Page.ClientScript.RegisterStartupScript(this.GetType(), "WindowScript", script, true);

并在您的课程中定义以下URL检查方法:

and define the following URL check method in your class:

public static bool UrlExists(string url)
{
   try
   {
      var request = WebRequest.Create(url) as HttpWebRequest;
      if (request == null) return false;
      request.Method = "HEAD";
      using (var response = (HttpWebResponse)request.GetResponse())
      {
         return response.StatusCode == HttpStatusCode.OK;
      }
   }
   catch (UriFormatException)
   {
      //Invalid Url
      return false;
   }
   catch (WebException)
   {
      //Unable to access url
      return false;
   }
}

我完全相信UrlExists方法能够: http://paigecsharp.blogspot.ca/2011/01/verify-url-exists.html

I give full credit to the UrlExists method to: http://paigecsharp.blogspot.ca/2011/01/verify-url-exists.html

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