DefaultHttpHandler 類別

定義

public ref class DefaultHttpHandler : System::Web::IHttpAsyncHandler

public class DefaultHttpHandler : System.Web.IHttpAsyncHandler

type DefaultHttpHandler = class
    interface IHttpAsyncHandler
    interface IHttpHandler

Public Class DefaultHttpHandler
Implements IHttpAsyncHandler

繼承

Object

DefaultHttpHandler

實作

IHttpAsyncHandler IHttpHandler

範例

以下程式碼範例示範如何從類別衍生 DefaultHttpHandler 出自訂的 HTTP 處理器。

public class AsyncDefaultHttpHandler : DefaultHttpHandler
{
    private HttpContext _context;

    public override IAsyncResult BeginProcessRequest(
      HttpContext context, AsyncCallback callback, object state)
    {
        AsyncResultSample ar = new AsyncResultSample(callback, state);
        _context = context;

        return ar;
    }

    public override void EndProcessRequest(IAsyncResult result)
    {
        _context.Response.Write("EndProcessRequest called.");
    }

    // This method should not be called asynchronously.
    public override void ProcessRequest(HttpContext context)
    {
        throw new InvalidOperationException(
                  "Asynchronous processing failed.");
    }

    // Enables pooling when set to true
    public override bool IsReusable
    {
        get { return true; }
    }
}

// Tracks state between the begin and end calls.
class AsyncResultSample : IAsyncResult
{
    private AsyncCallback callback = null;
    private Object asyncState;
    private Boolean isCompleted;

    internal AsyncResultSample(AsyncCallback cb, Object state)
    {
        this.callback = cb;
        asyncState = state;
        isCompleted = false;
    }

    public object AsyncState
    {
        get
        {
            return asyncState;
        }
    }

    public bool CompletedSynchronously
    {
        get
        {
            return false;
        }
    }

    public WaitHandle AsyncWaitHandle
    {
        get
        {
            throw new InvalidOperationException(
                      "ASP.NET should not use this property .");
        }
    }

    public bool IsCompleted
    {
        get
        {
            return isCompleted;
        }
    }

    internal void SetCompleted()
    {
        isCompleted = true;
        if (callback != null)
        {
            callback(this);
        }
    }
}

Public Class defaulthttpexampleVB
    Inherits DefaultHttpHandler

    Private _context As HttpContext

    Public Overrides Function BeginProcessRequest _
        (ByVal context As HttpContext, _
         ByVal callback As AsyncCallback, _
         ByVal state As Object) As IAsyncResult

        Dim ar As New AsyncResultSample(callback, state)
        _context = context

        Return (ar)
    End Function

    Public Overrides Sub EndProcessRequest(ByVal result As IAsyncResult)
        _context.Response.Write("EndProcessRequest called.")
    End Sub

    ' This method should not be called asynchronously.
    Public Overrides Sub ProcessRequest(ByVal context As HttpContext)
        Throw New InvalidOperationException _
          ("Asynchronous processing failed.")
    End Sub

    ' Enables pooling when set to true
    Public Overrides ReadOnly Property IsReusable() As Boolean
        Get
            Return True
        End Get
    End Property
End Class

' Tracks state between the begin and end calls.
Class AsyncResultSample
    Implements IAsyncResult
    Private callback As AsyncCallback = Nothing
    Private _asyncState As Object
    Private _isCompleted As Boolean

    Friend Sub New(ByVal cb As AsyncCallback, ByVal state As Object)
        Me.callback = cb
        _asyncState = state
        _isCompleted = False
    End Sub

    Public ReadOnly Property AsyncState() As Object _
      Implements IAsyncResult.AsyncState
        Get
            Return _asyncState
        End Get
    End Property

    Public ReadOnly Property CompletedSynchronously() _
      As Boolean Implements IAsyncResult.CompletedSynchronously
        Get
            Return False
        End Get
    End Property

    Public ReadOnly Property AsyncWaitHandle() _
      As WaitHandle Implements IAsyncResult.AsyncWaitHandle
        Get
            Throw New InvalidOperationException _
              ("ASP.NET should not use this property .")
        End Get
    End Property

    Public ReadOnly Property IsCompleted() _
      As Boolean Implements IAsyncResult.IsCompleted
        Get
            Return IsCompleted
        End Get
    End Property

    Friend Sub SetCompleted()
        _isCompleted = True
        If (callback <> Nothing) Then
            callback(Me)
        End If
    End Sub
End Class

備註

當 DefaultHttpHandler 物件在 HTTP 管線中攔截了兩個請求攔截都已透過 Internet Information Services（IIS） 6.0 配置，且請求的擴充名沒有明確綁定時，會攔截 HTTP 管線中的來電請求。

請求攔截可透過 IIS 6.0 引入的通配碼應用程式映射功能設定。

該 DefaultHttpHandler 類別實作介面 IHttpAsyncHandler 以提供非同步請求處理。 關於 HTTP 處理器的一般資訊，請參閱 HTTP 處理器與 HTTP 模組概述。 此外，欲了解更多資訊，請參閱以下內容：

• 關於建立非同步 HTTP 處理器，請參見 「攻略：建立非同步 HTTP 處理器」。

• 關於註冊 HTTP 處理器，請參見 「如何註冊：註冊 HTTP 處理器」。

類別可以從該 DefaultHttpHandler 類別衍生，以提供客製化的請求處理。 從 DefaultHttpHandler 衍生出的非同步 HTTP 處理器可以覆寫該 BeginProcessRequest 方法，改變請求的處理方式。

DefaultHttpHandler 不使用 ASP.NET 錯誤。 現有使用 IIS 錯誤或專有 ISAPI 自訂錯誤機制的內容，則可保持不變。

另請參閱

• 如何：註冊 HTTP 處理器
• 如何：建立非同步 HTTP 處理器