使用一个HttpModule拦截Http请求，来检测页面刷新(F5或正常的请求)

01    function newGuid() {
02        var g = "";
03        for (var i = 0; i < 32; i++) {
04            g += Math.floor(Math.random() * 0xF).toString(0xF);
05        }
06        return g;
07    }
08     
09    //gets a new guid and assigns its value to the hidden field
10    function createPageIdentifier() {
11        var guid = this.newGuid();
12        document.getElementById(‘__REFRESH_FIELD‘).value = guid;
13    }

01    private static Guid GetPageGuid(Page page)
02            {
03                string str = page.Request.Form["__REFRESH_FIELD"];
04                return (!string.IsNullOrEmpty(str) ? new Guid(str) : Guid.Empty);
05            }
06     
07            public void Init(HttpApplication application)
08            {
09                guids = new Queue(queueSize);
10     
11                application.PreRequestHandlerExecute += new EventHandler(RefreshModule.Application_PreRequestHandlerExecute);
12            }
13     
14            private static void Page_Init(object sender, EventArgs e)
15            {
16                Page page = sender as Page;
17                if (page != null)
18                {
19                    page.ClientScript.RegisterOnSubmitStatement(typeof(RefreshModule), "onsubmit", "createPageIdentifier();");
20                    page.ClientScript.RegisterHiddenField("__REFRESH_FIELD", "");
21     
22                    HttpContext.Current.Items["IsRefreshed"] = false;
23                    if (page.Request.HttpMethod == "POST")
24                    {
25                        Guid pageGuid = GetPageGuid(page);
26                        bool flag = guids.Contains(pageGuid);
27                        HttpContext.Current.Items["IsRefreshed"] = flag;
28                        if (!flag && (pageGuid != Guid.Empty))
29                        {
30                            guids.Enqueue(pageGuid);
31                            if (guids.Count > queueSize)
32                            {
33                                guids.Dequeue();
34                            }
35                        }
36                    }
37                }
38            }