为什么在从客户端调用PageMethod时创建页面实例

Question

作为ASP中的PageMethods。. NET需要静态方法并标记为web方法，我的印象是，当调用页面方法时，不会创建该特定页面的实例。

但是当我尝试在构造函数中放置一个断点时，每次调用pagemethod时它都会被击中。谁能告诉我构造实例需要什么?

感谢服务器端

public partial class PageMethod : System.Web.UI.Page
{
    public PageMethod()
    {
    }
    [System.Web.Services.WebMethod()]
    public static string GetMessage()
    {
        return "Page Method Call";
    }
}

客户端(使用JQuery)

$.ajax({ type: 'POST',
                url: /PageMethod.aspx/GetMessage,
                data: null,
                success: onSuccess,
                contentType: "application/json; charset=utf-8",
                dataType: 'JSON',
                error: onError      
            });

Answer 1

EDIT

构造函数确实被调用!!参见pagememethod调用的callstack:

PageMethodTest_WebApplication3.DLL!PageMethodTest_WebApplication3._Default._Default() Line 9    C#
  App_Web_iielssqo.dll!ASP.default_aspx.default_aspx() + 0x43 bytes C#
  App_Web_iielssqo.dll!__ASP.FastObjectFactory_app_web_iielssqo.Create_ASP_default_aspx() + 0x43 bytes  C#
  System.Web.dll!System.Web.Compilation.BuildResultCompiledType.CreateInstance() + 0x21 bytes   
  System.Web.dll!System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(System.Web.VirtualPath virtualPath, System.Type requiredBaseType, System.Web.HttpContext context, bool allowCrossApp, bool noAssert) + 0x78 bytes    
  System.Web.dll!System.Web.UI.PageHandlerFactory.GetHandlerHelper(System.Web.HttpContext context, string requestType, System.Web.VirtualPath virtualPath = {/Default.aspx}, string physicalPath) + 0x22 bytes  
  System.Web.dll!System.Web.UI.PageHandlerFactory.System.Web.IHttpHandlerFactory2.GetHandler(System.Web.HttpContext context, string requestType, System.Web.VirtualPath virtualPath, string physicalPath) + 0x29 bytes  
  System.Web.dll!System.Web.HttpApplication.MapHttpHandler(System.Web.HttpContext context, string requestType, System.Web.VirtualPath path, string pathTranslated = "C:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\PageMethodTest_WebApplication3\PageMethodTest_WebApplication3\Default.aspx", bool useAppConfig) + 0xa1 bytes  

ASP。. NET引擎将请求从pagememethod路由到aspx-handler-factory (PageHandlerFactory)。据我所知，这是ASP.NET的内部逻辑。因此，它是正确的:)

现在检查asmx-webmethod调用:

  PageMethodTest_WebApplication3.DLL!PageMethodTest_WebApplication3.WebService1.HelloWorld() Line 22    C#
  [Native to Managed Transition]    
  [Managed to Native Transition]    
  System.Web.Extensions.dll!System.Web.Script.Services.WebServiceMethodData.CallMethod(object target, System.Collections.Generic.IDictionary<string,object> parameters) + 0x15c bytes   
  System.Web.Extensions.dll!System.Web.Script.Services.WebServiceMethodData.CallMethodFromRawParams(object target, System.Collections.Generic.IDictionary<string,object> parameters) + 0x1f bytes   
  System.Web.Extensions.dll!System.Web.Script.Services.RestHandler.InvokeMethod(System.Web.HttpContext context = {System.Web.HttpContext}, System.Web.Script.Services.WebServiceMethodData methodData = {System.Web.Script.Services.WebServiceMethodData}, System.Collections.Generic.IDictionary<string,object> rawParams) + 0x61 bytes    
  System.Web.Extensions.dll!System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(System.Web.HttpContext context = {System.Web.HttpContext}, System.Web.Script.Services.WebServiceMethodData methodData) + 0x55 bytes    
  System.Web.Extensions.dll!System.Web.Script.Services.RestHandler.ProcessRequest(System.Web.HttpContext context) + 0xc bytes   
  System.Web.Extensions.dll!System.Web.Script.Services.ScriptHandlerFactory.HandlerWrapper.ProcessRequest(System.Web.HttpContext context) + 0xe bytes   
  System.Web.dll!System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() + 0xb6 bytes   

这里使用另一个httphandler-factory - ScriptHandlerFactory.

PS Moorthy，谢谢!好问题:)"活到老学到老!"'

---

static/[WebMethod] - cos page方法由ajax单独调用(不需要创建页面)。

如果你想有Page实例，你应该使用UpdatePanel或AJAX。. NET控件(例如DevExpress, AjaxToolKit)