ASP.NET AJAX in Action—ScriptManager异常处理示例
使用 OnAsyncPostBackError="ScriptManager1_AsyncPostBackError" 捕获异常，
使用ScriptManager1.AsyncPostBackErrorMessage = e.Exception.Message; 输出异常信息，在前台添加Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler); 方法，当回发结束时，在div中显示异常消息！
类似的方法有：
add_beginRequest() add_beginRequest(handler) Variant
add_endRequest() add_endRequest(handler) Variant
add_initializeRequest() add_initializeRequest(handler) Variant
add_pageLoaded() add_pageLoaded(handler) Variant
add_pageLoading() add_pageLoading(handler) Variant
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
protected void ErrorProcessClick_Handler(object sender, EventArgs e)
{
// This handler demonstrates an error condition. In this example
// the server error gets intercepted on the client and an alert is shown.
throw new ArgumentException();
}
protected void SuccessProcessClick_Handler(object sender, EventArgs e)
{
// This handler demonstrates no server side exception.
UpdatePanelMessage.Text = "The asynchronous postback completed successfully.";
}
protected void ScriptManager1_AsyncPostBackError(object sender, AsyncPostBackErrorEventArgs e)
{
ScriptManager1.AsyncPostBackErrorMessage = e.Exception.Message;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>PageRequestManager endRequestEventArgs Example</title>
<style type="text/css">
body {
font-family: Tahoma;
}
#AlertDiv{
left: 40%; top: 40%;
position: absolute; width: 200px;
padding: 12px;
border: #000000 1px solid;
background-color: white;
text-align: left;
visibility: hidden;
z-index: 99;
}
#AlertButtons{
position: absolute;
right: 5%;
bottom: 5%;
}
</style>
</head>
<body >
<form runat="server">
<div>
<asp:ScriptManager runat="server"
OnAsyncPostBackError="ScriptManager1_AsyncPostBackError">
</asp:ScriptManager>
<script type="text/javascript" language="javascript">
var divElem = 'AlertDiv';
var messageElem = 'AlertMessage';
var errorMessageAdditional = 'Please try again.';
var bodyTag = 'bodytag';
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(EndRequestHandler);
function ToggleAlertDiv(visString)
{
if (visString == 'hidden')
{
$get(bodyTag).style.backgroundColor = 'white';
}
else
{
$get(bodyTag).style.backgroundColor = 'gray';
}
var adiv = $get(divElem);
adiv.style.visibility = visString;
}
function ClearErrorState() {
$get(messageElem).innerHTML = '';
ToggleAlertDiv('hidden');
}
function EndRequestHandler(sender, args)
{
if (args.get_error() != undefined && args.get_error().httpStatusCode == '500')
{
var errorMessage = args.get_error().message
args.set_errorHandled(true);
ToggleAlertDiv('visible');
$get(messageElem).innerHTML = '"' +
errorMessage + '" ' + errorMessageAdditional;
}
}
</script>
<asp:UpdatePanel runat="Server" UpdateMode="Conditional" >
<ContentTemplate>
<asp:Panel runat="server" GroupingText="Update Panel">
<asp:Label runat="server" />
<br />
Last update:
<%= DateTime.Now.ToString() %>
.
<br />
<asp:Button runat="server" Text="Submit Successful Async Postback"
OnClick="SuccessProcessClick_Handler" OnClientClick="ClearErrorState()" />
<asp:Button runat="server" Text="Submit Async Postback With Error"
OnClick="ErrorProcessClick_Handler" OnClientClick="ClearErrorState()" />
<br />
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
<div >
<div >
</div>
<br />
<div >
<input type="button" value="OK"
runat="server" onclick="ClearErrorState()" />
</div>
</div>
</form>
</body>
</html>