最近一些使用URLRewriting的朋友們有時候會遇到asp.net Ajax和AJAX Control Toolkit控件不能正常工作的現象，對于沒有相關經驗的開發者來說相當棘手。本篇通過案例分析和相對的解決方案來討論在使用ASP.NET AJAX 與 URLRewriting 時應當注意到的一些兼容性問題。
一般簡單的URLRewriting應用都是對來自客戶端對資源的Request進行路徑重定向，比較典型的寫法如同下列代碼1 和代碼2：
代碼1：
// If the requested file exists if (File.Exists(Request.PhysicalPath)) { // Do nothing here, just serve the file } // If the file does not exist then else if (!File.Exists(Request.PhysicalPath)) { // Get the URL requested by the user string sRequestedURL = Request.Path.Replace(".aspx", "").Replace("/gratis24/",""); // You can retrieve the ID of the content from database that is // relevant to this requested URL (as per your business logic) string sId; sId = GetContentIDByPath(sRequestedURL); // The ShowContents.aspx page should show contents relevant to // the ID that is passed here string sTargetURL = "~/Kategori.aspx?category=" + sId; // Owing to RewritePath, the user will see requested URL in the // address bar // The second argument should be false, to keep your references // to images, CSS files Context.RewritePath(sTargetURL, false);
代碼2：
//in global.asax void application_BeginRequest(object sender, EventArgs e) { System.Web.HttpContext httpContext = HttpContext.Current; String currentURL = httpContext.Request.Path.ToLower(); //Creates the physical path on the server string physicalPath = httpContext.Server.MapPath(currentURL.Substring(currentURL.LastIndexOf("/") + 1)); //checks to see if the file does not exsists. if (!System.IO.File.Exists(physicalPath) && !currentURL.EndsWith("webresource.axd")) { string reWritePage = "ViewPRofile.aspx"; httpContext.RewritePath(reWritePage); } }
然而，當我們使用上面的代碼進行URLRewriting，并且在頁面中使用ASP.NET AJAX 或 AJAX Control Toolkit的話，將會得到：'sys' is undefined 錯誤警告，而AJAX控件不能正常工作，totally not work.
很顯然，'sys' is undefined 告訴我們 ASP.NET AJAX框架沒有正常加載，根據分析可知，sys的定義是在腳本資源文件ScriptResource.axd中的，然而在上面的URLRewriting代碼中，我們并沒有對ScriptResource.axd進行特殊處理，導致該資源被重定向，沒有正常加載。所以導致了ASP.NET AJAX不工作的問題。
知道了原因，我們就要修改URLRewriting的代碼，為ScriptResource.axd增加一個例外：
代碼1的解決方案：
在CheckPath時加入特例
private static void CheckPath(string path){ if (!string.Equals(path, VirtualPathUtility.ToAbsolute("~/ScriptResource.axd"), StringComparison.OrdinalIgnoreCase)) //it should be at the root. { Throw404(); }}
代碼2的解決方案：
與1同理，在IO判斷時加上特例，修改如下：
void Application_BeginRequest(object sender, EventArgs e) { System.Web.HttpContext httpContext = HttpContext.Current; String currentURL = httpContext.Request.Path.ToLower(); //Creates the physical path on the server string physicalPath = httpContext.Server.MapPath(currentURL.Substring(currentURL.LastIndexOf("/") + 1)); //checks to see if the file does not exsists. if (!System.IO.File.Exists(physicalPath) && !currentURL.EndsWith("webresource.axd") && !currentURL.EndsWith("ScriptResource.axd")) { string reWritePage = "ViewProfile.aspx"; httpContext.RewritePath(reWritePage); } }
至此，可解決該問題。
相關case：
http://forums.asp.net/t/1178119.aspx
http://forums.asp.net/p/1356089/2795441.aspx#2795441
Thanks.
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