異步 HttpContext.Current實(shí)現(xiàn)取值的方法(解決異步Application,Session,Cache...等失效的問(wèn)題)

2020-01-18 01:11:23

字體：大中小

供稿：網(wǎng)友

回答的也多數(shù)都是:引用System.Web,不要用HttpContext.Current.Application應(yīng)該用System.Web.HttpContext.Current.Application,后來(lái)在網(wǎng)上看到一篇關(guān)于System.Runtime.Remoting.Messaging.CallContext這個(gè)類的詳細(xì)介紹才知道,原來(lái)HttpContext.Current是基于System.Runtime.Remoting.Messaging.CallContext這個(gè)類,子線程和異步線程都無(wú)法訪問(wèn)到主線程在CallContext中保存的數(shù)據(jù)。所以在異步執(zhí)行的過(guò)程會(huì)就會(huì)出現(xiàn)HttpContext.Current為null的情況,為了解決子線程能夠得到主線程的HttpContext.Current數(shù)據(jù),需要在異步前面就把HttpContext.Current用HttpContext的方式存起來(lái),然后能過(guò)參數(shù)的形式傳遞進(jìn)去,下面看看實(shí)現(xiàn)的方法:

復(fù)制代碼代碼如下:

public HttpContext context 
{ 
get { return HttpContext.Current; } 
set { value = context; } 
} 

然后建立一個(gè)委托

復(fù)制代碼代碼如下:

public delegate string delegategetResult(HttpContext context);

下面就是實(shí)現(xiàn)過(guò)程的編碼

復(fù)制代碼代碼如下:

protected void Page_Load(object sender, EventArgs e) 
{ 
context = HttpContext.Current; 
delegategetResult dgt = testAsync; 
IAsyncResult iar = dgt.BeginInvoke(context, null, null); 
string result = dgt.EndInvoke(iar); 
Response.Write(result); 
} 

public static string testAsync(HttpContext context) 
{ 
if (context.Application["boolTTS"] == null) 
{ 
Hashtable ht = (Hashtable)context.Application["TTS"]; 
if (ht == null) 
{ 
ht = new Hashtable(); 
} 

if (ht["A"] == null) 
{ 
ht.Add("A", "A"); 
} 

if (ht["B"] == null) 
{ 
ht.Add("B", "B"); 
} 

context.Application["TTS"] = ht; 
} 

Hashtable hts = new Hashtable(); 
hts = (Hashtable)context.Application["TTS"]; 
if (hts["A"] != null) 
{ 
return "恭喜,中大獎(jiǎng)呀"; 
} 
else 
{ 
return "我猜你快中獎(jiǎng)了"; 
} 
} 