使用ASP.NET AJAX访问Script Method时启用客户端缓存

<asp:ScriptManager ID="ScriptManager1" runat="server" ScriptMode="Debug">
<Services>
<asp:ServiceReference Path="CacheService.asmx" />
</Services>
</asp:ScriptManager>
<script language="javascript" type="text/javascript">
var count = 0;

function getServerTime()
{
window.count ++;
CacheService.GetServerTime(onSucceeded);
}

function onSucceeded(result)
{
Sys.Debug.trace(result.format("HH:mm:ss"));

if (count < 6)
{
window.setTimeout(getServerTime, 3000);
}
else
{
window.count = 0;
}
}
</script>
<input type="button" value="GetCurrentTime" onclick="getServerTime()" />
<br /><br />
<textarea cols="20" rows="10" id="TraceConsole"></textarea>

[ScriptService]
public class CacheService  : System.Web.Services.WebService
{
[WebMethod]
public DateTime GetServerTime()
{
return DateTime.Now;
}    
}

[WebMethod(CacheDuration=10)]
public DateTime GetServerTime()
{
return DateTime.Now;
}