检查网站是否在线，限制超时时间

本文关键字：超时 时间 网站 是否 在线 检查 | 更新日期: 2023-09-27 17:50:11

我想做一个功能，检查一个网站是否在线，但超时有一些问题。我想将其限制为最大3秒，如果在3秒内没有响应，我应该将页面视为离线。

我的尝试:

class OnlineCheck
    {
        public static bool IsOnline(string url)
        {
            try
            {
                WebClient webclient = new WebClient();
                webclient.Headers.Add(HttpRequestHeader.KeepAlive, "1000");
                webclient.OpenRead(url);
            }
            catch { return false; }
            return true;
        }
    }

检查网站是否在线，限制超时时间

WebClient不支持超时。但是你可以使用HttpWebRequest!

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Endpoint);
request.Timeout=3000;
request.GetResponse();

如果您想检查站点是否在线，那么您对页面的内容并不真正感兴趣，只是希望得到一个响应。为了提高效率，您应该只请求http头。下面是一个简单的例子:

private static IEnumerable<HttpStatusCode> onlineStatusCodes = new[]
{
    HttpStatusCode.Accepted,
    HttpStatusCode.Found,
    HttpStatusCode.OK,
    // add more codes as needed
};
private static bool IsSiteOnline(string url, int timeout)
{
    HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
    {
        if (request != null)
        {
            request.Method = "HEAD"; // get headers only
            request.Timeout = timeout;
            using (var response = request.GetResponse() as HttpWebResponse)
            {
                return response != null && onlineStatusCodes.Contains(response.StatusCode);
            }
        }
    }
    return false;
}

使用HttpWebRequest而不是WebClient。HttpWebRequest类有一个timeout属性

你可以试试下面的代码:

        System.Net.WebRequest r = System.Net.WebRequest.Create("http://www.google.com");
        r.Timeout = 3000;
        System.Net.WebProxy proxy = new System.Net.WebProxy("<proxy address>");
        System.Net.NetworkCredential credentials = new System.Net.NetworkCredential();
        credentials.Domain = "<domain>";
        credentials.UserName = "<login>";
        credentials.Password = "<pass>";
        proxy.Credentials = credentials;
        r.Proxy = proxy;
        try
        {
            System.Net.WebResponse rsp = r.GetResponse();
        }
        catch (Exception)
        {
            MessageBox.Show("Is not avaliable");
            return;
        }
        MessageBox.Show("Avaliable!");

static bool isOnline (string URL)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
    request.Timeout = 3000;
    try
    {
        WebResponse resp = request.GetResponse();
    }
    catch (WebException e)
    {
        if (((HttpWebResponse)e.Response).StatusCode == HttpStatusCode.NotFound)
        {
            return false;
        }
    }
    return true;
}
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