定期從客戶端調用服務器,如果沒有答案或不期待答案 - 顯示錯誤消息。
爲網絡形成: 創建的處理程序與ProcessRequest
implemetation這樣的:
public void ProcessRequest(HttpContext context)
{
context.Response.ContentType = "text/plain";
context.Response.Write("Ok");
}
爲MVC: 創建一個簡單的結果是這樣的動作:
public ActionResult CheckInternetConnection()
{
return Json("Ok");
}
當然
,這個請求處理程序不應該要求任何授權或其他預處理
然後創建JS timer
和方法,用於請求
var maxTime = <your interval time>;
var timer;
//write own method for check request
function performRequest() {
var xhr = new XMLHttpRequest();
// reserve 1 sec for timeout function execution
// if we didn't - you can get a situation when
// simultaneously performing more than 1 request
xhr.timeout = maxTime - 1000;
xhr.ontimeout = function {
//waiting to long
alert('<your message>');
window.clearInterval(timer);
};
xhr.open('GET', '<url of your check connection handler>', true);
xhr.send();
xhr.onreadystatechange = function() {
if (xhr.readyState != 4)
return;
if (xhr.responseText !== 'OK') {
//Can't access to handler
alert('<your message>');
window.clearInterval(timer);
}
}
}
//after page load start request timer
document.onload += function() {
timer = window.setInterval(performRequest, maxTime);
}
我還沒有調試代碼。
Aehem。未找到服務器,無法連接意味着瀏覽器無法連接到服務器。那麼服務器應該怎樣才能向瀏覽器發送消息呢? – Thomas
選中此項:http://www.asp.net/web-forms/overview/older-versions-getting-started/deploying-web-site-projects/displaying-a-custom-error-page-cs –
是的。但有什麼辦法來顯示緩存中的消息? – deepak