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IHttpHandlerFactory.GetHandler(HttpContext, String, String, String) Metoda

Definice

Vrátí instanci třídy, která implementuje IHttpHandler rozhraní .

public:
 System::Web::IHttpHandler ^ GetHandler(System::Web::HttpContext ^ context, System::String ^ requestType, System::String ^ url, System::String ^ pathTranslated);
public System.Web.IHttpHandler GetHandler (System.Web.HttpContext context, string requestType, string url, string pathTranslated);
abstract member GetHandler : System.Web.HttpContext * string * string * string -> System.Web.IHttpHandler
Public Function GetHandler (context As HttpContext, requestType As String, url As String, pathTranslated As String) As IHttpHandler

Parametry

context
HttpContext

Instance HttpContext třídy, která poskytuje odkazy na vnitřní objekty serveru (například Request, Response, Sessiona Server) používané ke službě požadavků HTTP.

requestType
String

Metoda přenosu dat HTTP (GET nebo POST), kterou klient používá.

url
String

Hodnota RawUrl požadovaného prostředku.

pathTranslated
String

k PhysicalApplicationPath požadovanému prostředku.

Návraty

Nový IHttpHandler objekt, který zpracovává požadavek.

Příklady

Následující příklad kódu ukazuje, jak vytvořit vlastní objekty obslužné rutiny v reakci na požadavek klienta. Příklad má dvě části:

  • Třída továrny obslužné rutiny.

  • Výňatek ze souboru Web.config

První část příkladu ukazuje, jak vytvořit vlastní objekty obslužné rutiny v reakci na požadavek klienta na stránku s názvem abc.aspx nebo xyz.aspx. Třída objektu továrny obslužné rutiny s názvem hwf vytvoří příslušný objekt obslužné rutiny v závislosti na požadované stránce.

// Name this C# file HandlerFactoryTest.cs and compile it with the
// command line: csc /t:Library /r:System.Web.dll HandlerFactoryTest.cs.
// Copy HandlerFactoryTest.dll to your \bin directory.

namespace test
{
   using System;
   using System.Web;

   // Factory class that creates a handler object based on a request
   // for either abc.aspx or xyz.aspx as specified in the Web.config file.
   public class MyFactory : IHttpHandlerFactory
   {
      [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
      public virtual IHttpHandler GetHandler(HttpContext context,
                                             String requestType,
                                             String url,
                                             String pathTranslated)
      {
         String fname = url.Substring(url.LastIndexOf('/')+1);
         String cname = fname.Substring(0, fname.IndexOf('.'));
         String className = "test." + cname;

         Object h = null;

         // Try to create the handler object.
         try
         {
            // Create the handler by calling class abc or class xyz.
            h = Activator.CreateInstance(Type.GetType(className));
         }
         catch(Exception e)
         {
            throw new HttpException("Factory couldn't create instance " +
                                    "of type " + className, e);
         }
         return (IHttpHandler)h;
      }

      // This is a must override method.
      public virtual void ReleaseHandler(IHttpHandler handler)
      {
      }
   }

   // Class definition for abc.aspx handler.
   public class abc : IHttpHandler
   {
      public virtual void ProcessRequest(HttpContext context)
      {
         context.Response.Write("<html><body>");
         context.Response.Write("<p>ABC Handler</p>\n");
         context.Response.Write("</body></html>");
      }

      public virtual bool IsReusable
      {
         get { return true; }
      }
   }

   // Class definition for xyz.aspx handler.
   public class xyz : IHttpHandler
   {
      public virtual void ProcessRequest(HttpContext context)
      {
         context.Response.Write("<html><body>");
         context.Response.Write("<p>XYZ Handler</p>\n");
         context.Response.Write("</body></html>");
      }

      public virtual bool IsReusable
      {
         get { return true; }
      }
   }
}

/*
______________________________________________________________

To use the handler factory, use the following lines in a
Web.config file.

<configuration>
   <system.web>
      <httpHandlers>
         <add verb="*" path="abc.aspx" type="test.MyFactory,HandlerFactoryTest" />
         <add verb="*" path="xyz.aspx" type="test.MyFactory,HandlerFactoryTest" />
      </httpHandlers>
   </system.web>
</configuration>
*/
' Name this Visual Basic file HandlerFactoryTest.vb and compile it with 
' the command line: vbc /t:Library /r:System.Web.dll HandlerFactoryTest.vb.
' Copy HandlerFactoryTest.dll to your \bin directory.
Imports System.Web

Namespace test    
    
    ' Factory class that creates a handler object based on a request 
    ' for either abc.aspx or xyz.aspx as specified in the Web.config file.
    Public Class MyFactory
        Implements IHttpHandlerFactory
        
        <System.Security.Permissions.PermissionSetAttribute(System.Security.Permissions.SecurityAction.Demand, Name:="FullTrust")> _
        Public Overridable Function GetHandler(context As HttpContext, _
        requestType As String, url As String, pathTranslated As String) _
        As IHttpHandler _
        Implements IHttpHandlerFactory.GetHandler
        
            Dim fname As String = url.Substring(url.LastIndexOf("/"c) + 1)
            Dim cname As String = fname.Substring(0, fname.IndexOf("."c))
            Dim className As String = "test." & cname
            
            Dim h As Object = Nothing
            
            Try ' to create the handler object.
                ' Create by calling class abc or class xyz.
                h = Activator.CreateInstance(Type.GetType(className))
            Catch e As Exception
                Throw New HttpException("Factory couldn't create instance " & _
                    "of type " & className, e)
            End Try
            Return CType(h, IHttpHandler)
        End Function
        
        
        ' This is a must override method.
        Public Overridable Sub ReleaseHandler(handler As IHttpHandler) _
        Implements IHttpHandlerFactory.ReleaseHandler
        
        End Sub
        
    End Class
    
    
    ' Class definition for abc.aspx handler.
    Public Class abc
        Implements IHttpHandler
        
        Public Overridable Sub ProcessRequest(context As HttpContext) _
        Implements IHttpHandler.ProcessRequest
        
            context.Response.Write("<html><body>")
            context.Response.Write("<p>ABC Handler</p>" & _
                Microsoft.VisualBasic.ControlChars.CrLf)
            context.Response.Write("</body></html>")
        End Sub        
        
        Public Overridable ReadOnly Property IsReusable() As Boolean _
        Implements IHttpHandler.IsReusable
        
            Get
                Return True
            End Get
        End Property
    End Class
     
    ' Class definition for xyz.aspx handler.
    Public Class xyz
        Implements IHttpHandler
        
        Public Overridable Sub ProcessRequest(context As HttpContext) _
        Implements IHttpHandler.ProcessRequest
        
            context.Response.Write("<html><body>")
            context.Response.Write("<p>XYZ Handler</p>" & _
                Microsoft.VisualBasic.ControlChars.CrLf)
            context.Response.Write("</body></html>")
        End Sub
        
        
        Public Overridable ReadOnly Property IsReusable() As Boolean _
        Implements IHttpHandler.IsReusable
        
            Get
                Return True
            End Get
        End Property
    End Class
End Namespace

'______________________________________________________________
'
'To use the handler factory, use the following lines in a
'Web.config file. (be sure to remove the comment markers)
'
'         <add verb="*" path="abc.aspx" type="test.MyFactory,HandlerFactoryTest" />
'         <add verb="*" path="xyz.aspx" type="test.MyFactory,HandlerFactoryTest" />

Druhá část příkladu ukazuje Web.config výňatek ze souboru. Pokud chcete použít výše uvedený objekt pro vytváření obslužných rutin, přidejte do souboru Web.config následující řádky.

<configuration>   
  <system.web>   
    <httpHandlers>   
      <add verb="*" path="abc.aspx" type="test.MyFactory,HandlerFactoryTest" />   
      <add verb="*" path="xyz.aspx" type="test.MyFactory,HandlerFactoryTest" />   
    </httpHandlers>   
  </system.web>  
</configuration>   

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