读DataSnap源代码（四）

继续篇中的

 function TCustomWebDispatcher.DispatchAction(Request: TWebRequest;
   Response: TWebResponse): Boolean;
 var
   I: Integer;
   Action, Default: TWebActionItem;
   Dispatch: IWebDispatch;
 begin
   FRequest := Request;
   FResponse := Response;
   I := ;
   Default := nil;
   if Response.Sent then
   begin
     Result := True;
     { Note that WebSnapSvr enabled apps have no way to mark response as sent }
     Exit;
   end;
   Result := DoBeforeDispatch(Request, Response) or Response.Sent;
   while not Result and (I < FActions.Count) do
   begin
     Action := FActions[I];
     Result := Action.DispatchAction(Request, Response, False);
     if Action.Default then Default := Action;
     Inc(I);
   end;
   // Dispatch to self registering components
   I := ;
   while not Result and (I < FDispatchList.Count) do
   begin
     if Supports(IInterface(FDispatchList.Items[I]), IWebDispatch, Dispatch) then
     begin
       Result := DispatchHandler(Self, Dispatch,
         Request, Response, False);
     end;
     Inc(I);
   end;

   if not Result and Assigned(Default) then
     Result := Default.DispatchAction(Request, Response, True);
   if Result and not Response.Sent then
     Result := DoAfterDispatch(Request, Response);

 end;

在第26行代码之前，是执行WebModule中的Action, 然后是遍例WebModule上的Component, 只要支持IWebDispatch，都有机会处理WEB请求。

当然就包括了   TDSHTTPWebDispatcher = class(TDSHTTPServerTransport, IWebDispatch)。 继续代码：

 function DispatchHandler(Sender: TObject; Dispatch: IWebDispatch; Request: TWebRequest; Response: TWebResponse;
   DoDefault: Boolean): Boolean;
 begin
   Result := False;
   if (Dispatch.Enabled and ((Dispatch.MethodType = mtAny) or
     (Request.MethodType = Dispatch.MethodType)) and
     Dispatch.Mask.Matches(string(Request.InternalPathInfo))) then
   begin
     Result := Dispatch.DispatchRequest(Sender, Request, Response);
   end;
 end;

function TDSHTTPWebDispatcher.DispatchRequest(Sender: TObject;
  Request: TWebRequest; Response: TWebResponse): Boolean;
begin
  try
    if Owner is TWebModule then
      DataSnapWebModule := TWebModule(Owner);
    try
      try
        RequiresServer;
        TDSHTTPServerWebBroker(Self.FHttpServer).DispatchDataSnap(Request, Response);
        Result := True;
      except
        on E: Exception do
        begin
          { Default to 500, like web services. }
          Response.StatusCode := 500;
          Result := True;
        end;
      end;
    except
      { Swallow any unexpected exception, it will bring down some web servers }
      Result := False;
    end;
  finally
    { Reset current DataSnapWebModule }
    DataSnapWebModule := nil;
  end;
end;

至此，WEB请求转入到WebModule中的TDSHTTPWebDispatcher来处理了。