实现虚函数C ++

Question

CefRequesthandler类中的

函数（cef_request_handler.h）：

virtual ReturnValue OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback) {


    return RV_CONTINUE;

  }

将函数复制到SimpleHandler类，如下所示。

virtual ReturnValue OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback) OVERRIDE;

将以下内容添加到SimpleHandler类文件中：

 #include "include/cef_request_handler.h"

我没有从Simplehandler类扩展CefRequestHandler类。我不认为这是必要的。

在我的Simplehandler.cc文件中，我实现了如下所示的函数：

CefRequestHandler::ReturnValue SimpleHandler::OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback){

CefRequest::ReferrerPolicy origin = REFERRER_POLICY_ALWAYS;
request->SetReferrer("www.google.com",origin);


    return RV_CONTINUE;

}

我收到以下错误：

error: no ‘CefRequestHandler::ReturnValue SimpleHandler::OnBeforeResourceLoad(CefRefPtr<CefBrowser>, CefRefPtr<CefFrame>, CefRefPtr<CefRequest>, CefRefPtr<CefRequestCallback>)’ member function declared in class ‘SimpleHandler’
       CefRefPtr<CefRequestCallback> callback){
                                             ^

CefRequestHandler::ReturnValue派生自CefRequestHandler类中的以下语句：

typedef cef_return_value_t ReturnValue;

我错过了什么会导致编译器说出no member function declared in class ‘SimpleHandler’？

simple_handler.h / SimpleHandler类

// Copyright (c) 2013 The Chromium Embedded Framework Authors. All rights
// reserved. Use of this source code is governed by a BSD-style license that
// can be found in the LICENSE file.

#ifndef CEF_TESTS_CEFSIMPLE_SIMPLE_HANDLER_H_
#define CEF_TESTS_CEFSIMPLE_SIMPLE_HANDLER_H_

#include "include/cef_client.h"

#include "include/cef_request_handler.h"




#include <list>

class SimpleHandler : public CefClient,
                      public CefDisplayHandler,
                      public CefLifeSpanHandler,
                      public CefLoadHandler {
 public:
  explicit SimpleHandler(bool use_views);
  ~SimpleHandler();

  // Provide access to the single global instance of this object.
  static SimpleHandler* GetInstance();

  // CefClient methods:
  virtual CefRefPtr<CefDisplayHandler> GetDisplayHandler() OVERRIDE {
    return this;
  }
  virtual CefRefPtr<CefLifeSpanHandler> GetLifeSpanHandler() OVERRIDE {
    return this;
  }
  virtual CefRefPtr<CefLoadHandler> GetLoadHandler() OVERRIDE {
    return this;
  }

  // CefDisplayHandler methods:
  virtual void OnTitleChange(CefRefPtr<CefBrowser> browser,
                             const CefString& title) OVERRIDE;

  // CefLifeSpanHandler methods:
  virtual void OnAfterCreated(CefRefPtr<CefBrowser> browser) OVERRIDE;
  virtual bool DoClose(CefRefPtr<CefBrowser> browser) OVERRIDE;
  virtual void OnBeforeClose(CefRefPtr<CefBrowser> browser) OVERRIDE;

  // CefLoadHandler methods:
  virtual void OnLoadError(CefRefPtr<CefBrowser> browser,
                           CefRefPtr<CefFrame> frame,
                           ErrorCode errorCode,
                           const CefString& errorText,
                           const CefString& failedUrl) OVERRIDE;

virtual ReturnValue OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback) OVERRIDE;

//{ return false; }



  // Request that all existing browser windows close.
  void CloseAllBrowsers(bool force_close);

  bool IsClosing() const { return is_closing_; }

 private:
  // Platform-specific implementation.
  void PlatformTitleChange(CefRefPtr<CefBrowser> browser,
                           const CefString& title);

  // True if the application is using the Views framework.
  const bool use_views_;

  // List of existing browser windows. Only accessed on the CEF UI thread.
  typedef std::list<CefRefPtr<CefBrowser> > BrowserList;
  BrowserList browser_list_;

  bool is_closing_;

  // Include the default reference counting implementation.
  IMPLEMENT_REFCOUNTING(SimpleHandler);
};

#endif  // CEF_TESTS_CEFSIMPLE_SIMPLE_HANDLER_H_

simple_handler.cc

// Copyright (c) 2013 The Chromium Embedded Framework Authors. All rights
// reserved. Use of this source code is governed by a BSD-style license that
// can be found in the LICENSE file.

#include "cefsimple/simple_handler.h"

#include <sstream>
#include <string>

#include "include/base/cef_bind.h"
#include "include/cef_app.h"
#include "include/views/cef_browser_view.h"
#include "include/views/cef_window.h"
#include "include/wrapper/cef_closure_task.h"
#include "include/wrapper/cef_helpers.h"
#include "include/cef_request_handler.h"

namespace {

SimpleHandler* g_instance = NULL;

}  // namespace

SimpleHandler::SimpleHandler(bool use_views)
    : use_views_(use_views),
      is_closing_(false) {
  DCHECK(!g_instance);
  g_instance = this;
}

SimpleHandler::~SimpleHandler() {
  g_instance = NULL;
}

// static
SimpleHandler* SimpleHandler::GetInstance() {
  return g_instance;
}

void SimpleHandler::OnTitleChange(CefRefPtr<CefBrowser> browser,
                                  const CefString& title) {
  CEF_REQUIRE_UI_THREAD();

  if (use_views_) {
    // Set the title of the window using the Views framework.
    CefRefPtr<CefBrowserView> browser_view =
        CefBrowserView::GetForBrowser(browser);
    if (browser_view) {
      CefRefPtr<CefWindow> window = browser_view->GetWindow();
      if (window)
        window->SetTitle(title);
    }
  } else {
    // Set the title of the window using platform APIs.
    PlatformTitleChange(browser, title);
  }
}

void SimpleHandler::OnAfterCreated(CefRefPtr<CefBrowser> browser) {
  CEF_REQUIRE_UI_THREAD();

  // Add to the list of existing browsers.
  browser_list_.push_back(browser);
}

 CefRequestHandler::ReturnValue SimpleHandler::OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback){

CefRequest::ReferrerPolicy origin = REFERRER_POLICY_ALWAYS;
request->SetReferrer("www.google.com",origin);


    return RV_CONTINUE;

}

bool SimpleHandler::DoClose(CefRefPtr<CefBrowser> browser) {
  CEF_REQUIRE_UI_THREAD();

  // Closing the main window requires special handling. See the DoClose()
  // documentation in the CEF header for a detailed destription of this
  // process.
  if (browser_list_.size() == 1) {
    // Set a flag to indicate that the window close should be allowed.
    is_closing_ = true;
  }

  // Allow the close. For windowed browsers this will result in the OS close
  // event being sent.
  return false;
}

void SimpleHandler::OnBeforeClose(CefRefPtr<CefBrowser> browser) {
  CEF_REQUIRE_UI_THREAD();

  // Remove from the list of existing browsers.
  BrowserList::iterator bit = browser_list_.begin();
  for (; bit != browser_list_.end(); ++bit) {
    if ((*bit)->IsSame(browser)) {
      browser_list_.erase(bit);
      break;
    }
  }

  if (browser_list_.empty()) {
    // All browser windows have closed. Quit the application message loop.
    CefQuitMessageLoop();
  }
}

void SimpleHandler::OnLoadError(CefRefPtr<CefBrowser> browser,
                                CefRefPtr<CefFrame> frame,
                                ErrorCode errorCode,
                                const CefString& errorText,
                                const CefString& failedUrl) {
  CEF_REQUIRE_UI_THREAD();

  // Don't display an error for downloaded files.
  if (errorCode == ERR_ABORTED)
    return;

  // Display a load error message.
  std::stringstream ss;
  ss << "<html><body bgcolor=\"white\">"
        "<h2>Failed to load URL " << std::string(failedUrl) <<
        " with error " << std::string(errorText) << " (" << errorCode <<
        ").</h2></body></html>";
  frame->LoadString(ss.str(), failedUrl);
}

void SimpleHandler::CloseAllBrowsers(bool force_close) {
  if (!CefCurrentlyOn(TID_UI)) {
    // Execute on the UI thread.
    CefPostTask(TID_UI,
        base::Bind(&SimpleHandler::CloseAllBrowsers, this, force_close));
    return;
  }

  if (browser_list_.empty())
    return;

  BrowserList::const_iterator it = browser_list_.begin();
  for (; it != browser_list_.end(); ++it)
    (*it)->GetHost()->CloseBrowser(force_close);
}

cef_request_handler.h Cefrequesthandler类

//
// The contents of this file must follow a specific format in order to
// support the CEF translator tool. See the translator.README.txt file in the
// tools directory for more information.
//

#ifndef CEF_INCLUDE_CEF_REQUEST_HANDLER_H_
#define CEF_INCLUDE_CEF_REQUEST_HANDLER_H_
#pragma once

#include "include/cef_auth_callback.h"
#include "include/cef_base.h"
#include "include/cef_browser.h"
#include "include/cef_frame.h"
#include "include/cef_resource_handler.h"
#include "include/cef_response.h"
#include "include/cef_response_filter.h"
#include "include/cef_request.h"
#include "include/cef_ssl_info.h"


///
// Callback interface used for asynchronous continuation of url requests.
///
/*--cef(source=library)--*/
class CefRequestCallback : public virtual CefBase {
 public:
  ///
  // Continue the url request. If |allow| is true the request will be continued.
  // Otherwise, the request will be canceled.
  ///
  /*--cef(capi_name=cont)--*/
  virtual void Continue(bool allow) =0;

  ///
  // Cancel the url request.
  ///
  /*--cef()--*/
  virtual void Cancel() =0;
};


///
// Implement this interface to handle events related to browser requests. The
// methods of this class will be called on the thread indicated.
///
/*--cef(source=client)--*/
class CefRequestHandler : public virtual CefBase {
 public:
  typedef cef_return_value_t ReturnValue;
  typedef cef_termination_status_t TerminationStatus;
  typedef cef_urlrequest_status_t URLRequestStatus;
  typedef cef_window_open_disposition_t WindowOpenDisposition;

  ///
  // Called on the UI thread before browser navigation. Return true to cancel
  // the navigation or false to allow the navigation to proceed. The |request|
  // object cannot be modified in this callback.
  // CefLoadHandler::OnLoadingStateChange will be called twice in all cases.
  // If the navigation is allowed CefLoadHandler::OnLoadStart and
  // CefLoadHandler::OnLoadEnd will be called. If the navigation is canceled
  // CefLoadHandler::OnLoadError will be called with an |errorCode| value of
  // ERR_ABORTED.
  ///
  /*--cef()--*/
  virtual bool OnBeforeBrowse(CefRefPtr<CefBrowser> browser,
                              CefRefPtr<CefFrame> frame,
                              CefRefPtr<CefRequest> request,
                              bool is_redirect) {
    return false;
  }

  ///
  // Called on the UI thread before OnBeforeBrowse in certain limited cases
  // where navigating a new or different browser might be desirable. This
  // includes user-initiated navigation that might open in a special way (e.g.
  // links clicked via middle-click or ctrl + left-click) and certain types of
  // cross-origin navigation initiated from the renderer process (e.g.
  // navigating the top-level frame to/from a file URL). The |browser| and
  // |frame| values represent the source of the navigation. The
  // |target_disposition| value indicates where the user intended to navigate
  // the browser based on standard Chromium behaviors (e.g. current tab,
  // new tab, etc). The |user_gesture| value will be true if the browser
  // navigated via explicit user gesture (e.g. clicking a link) or false if it
  // navigated automatically (e.g. via the DomContentLoaded event). Return true
  // to cancel the navigation or false to allow the navigation to proceed in the
  // source browser's top-level frame.
  ///
  /*--cef()--*/
  virtual bool OnOpenURLFromTab(CefRefPtr<CefBrowser> browser,
                                CefRefPtr<CefFrame> frame,
                                const CefString& target_url,
                                WindowOpenDisposition target_disposition,
                                bool user_gesture) {
    return false;
  }

  ///
  // Called on the IO thread before a resource request is loaded. The |request|
  // object may be modified. Return RV_CONTINUE to continue the request
  // immediately. Return RV_CONTINUE_ASYNC and call CefRequestCallback::
  // Continue() at a later time to continue or cancel the request
  // asynchronously. Return RV_CANCEL to cancel the request immediately.
  //
  ///
  /*--cef(default_retval=RV_CONTINUE)--*/
  virtual ReturnValue OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback) {

//CefRequest::ReferrerPolicy origin = REFERRER_POLICY_ALWAYS;
 // request->SetReferrer("www.google.com",origin);
    return RV_CONTINUE;

  }

  ///
  // Called on the IO thread before a resource is loaded. To allow the resource
  // to load normally return NULL. To specify a handler for the resource return
  // a CefResourceHandler object. The |request| object should not be modified in
  // this callback.
  ///
  /*--cef()--*/
  virtual CefRefPtr<CefResourceHandler> GetResourceHandler(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request) {

    return NULL;
    return new MyResourceHandler();
    //new MyResourceHandler();
  }

class MyResourceHandler : public CefResourceHandler
{
public:
MyResourceHandler()
//offset_(0)
{}

  bool ProcessRequest(CefRefPtr<CefRequest> request,
                              CefRefPtr<CefCallback> callback) {

    CefRefPtr<CefRequest> cef   = CefRequest::Create();
    request = cef;
    CefRequest::ReferrerPolicy origin = REFERRER_POLICY_ALWAYS;
    request->SetReferrer("www.google.com",origin);
    return true;
    //cef->SetReferrer("www.google.com",origin);};
};

   void GetResponseHeaders(CefRefPtr<CefResponse> response,
                                  int64& response_length,
                                  CefString& redirectUrl) ;


   bool ReadResponse(void* data_out,
                            int bytes_to_read,
                            int& bytes_read,
                            CefRefPtr<CefCallback> callback) ;

  bool CanGetCookie(const CefCookie& cookie) { return true; }


   bool CanSetCookie(const CefCookie& cookie) { return true; }


   void Cancel() ;

   void AddRef()const {} ;

bool Release() const { return true; }

 bool HasOneRef() const { return true; };

    //bool CefBase::HasOneRef();

    //void CefBase::AddRef() const;

 // bool ProcessRequest (CefRefPtr<CefRequest> request,
//CefRefPtr<CefCallback> callback){

//CefRefPtr<CefRequest> cef   = CefRequest::Create();
//cef = request;
//CefRequest::ReferrerPolicy origin = REFERRER_POLICY_ALWAYS;
//request->SetReferrer("www.google.com",origin);
//cef->SetReferrer("www.google.com",origin);

//}

//IMPLEMENT_REFCOUNTING(MyResourceHandler);
//IMPLEMENT_LOCKING(MyResourceHandler);
};

//void AddRef();

  ///
  // Called on the IO thread when a resource load is redirected. The |request|
  // parameter will contain the old URL and other request-related information.
  // The |new_url| parameter will contain the new URL and can be changed if
  // desired. The |request| object cannot be modified in this callback.
  ///
  /*--cef()--*/
  virtual void OnResourceRedirect(CefRefPtr<CefBrowser> browser,
                                  CefRefPtr<CefFrame> frame,
                                  CefRefPtr<CefRequest> request,
                                  CefString& new_url) {}

  ///
  // Called on the IO thread when a resource response is received. To allow the
  // resource to load normally return false. To redirect or retry the resource
  // modify |request| (url, headers or post body) and return true. The
  // |response| object cannot be modified in this callback.
  ///
  /*--cef()--*/
  virtual bool OnResourceResponse(CefRefPtr<CefBrowser> browser,
                                  CefRefPtr<CefFrame> frame,
                                  CefRefPtr<CefRequest> request,
                                  CefRefPtr<CefResponse> response) {
    return false;
  }

  ///
  // Called on the IO thread to optionally filter resource response content.
  // |request| and |response| represent the request and response respectively
  // and cannot be modified in this callback.
  ///
  /*--cef()--*/
  virtual CefRefPtr<CefResponseFilter> GetResourceResponseFilter(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefResponse> response) {
    return NULL;
  }

  ///
  // Called on the IO thread when a resource load has completed. |request| and
  // |response| represent the request and response respectively and cannot be
  // modified in this callback. |status| indicates the load completion status.
  // |received_content_length| is the number of response bytes actually read.
  ///
  /*--cef()--*/
  virtual void OnResourceLoadComplete(CefRefPtr<CefBrowser> browser,
                                      CefRefPtr<CefFrame> frame,
                                      CefRefPtr<CefRequest> request,
                                      CefRefPtr<CefResponse> response,
                                      URLRequestStatus status,
                                      int64 received_content_length) {}

  ///
  // Called on the IO thread when the browser needs credentials from the user.
  // |isProxy| indicates whether the host is a proxy server. |host| contains the
  // hostname and |port| contains the port number. |realm| is the realm of the
  // challenge and may be empty. |scheme| is the authentication scheme used,
  // such as "basic" or "digest", and will be empty if the source of the request
  // is an FTP server. Return true to continue the request and call
  // CefAuthCallback::Continue() either in this method or at a later time when
  // the authentication information is available. Return false to cancel the
  // request immediately.
  ///
  /*--cef(optional_param=realm,optional_param=scheme)--*/
  virtual bool GetAuthCredentials(CefRefPtr<CefBrowser> browser,
                                  CefRefPtr<CefFrame> frame,
                                  bool isProxy,
                                  const CefString& host,
                                  int port,
                                  const CefString& realm,
                                  const CefString& scheme,
                                  CefRefPtr<CefAuthCallback> callback) {
    return false;
  }

  ///
  // Called on the IO thread when JavaScript requests a specific storage quota
  // size via the webkitStorageInfo.requestQuota function. |origin_url| is the
  // origin of the page making the request. |new_size| is the requested quota
  // size in bytes. Return true to continue the request and call
  // CefRequestCallback::Continue() either in this method or at a later time to
  // grant or deny the request. Return false to cancel the request immediately.
  ///
  /*--cef()--*/
  virtual bool OnQuotaRequest(CefRefPtr<CefBrowser> browser,
                              const CefString& origin_url,
                              int64 new_size,
                              CefRefPtr<CefRequestCallback> callback) {
    return false;
  }

  ///
  // Called on the UI thread to handle requests for URLs with an unknown
  // protocol component. Set |allow_os_execution| to true to attempt execution
  // via the registered OS protocol handler, if any.
  // SECURITY WARNING: YOU SHOULD USE THIS METHOD TO ENFORCE RESTRICTIONS BASED
  // ON SCHEME, HOST OR OTHER URL ANALYSIS BEFORE ALLOWING OS EXECUTION.
  ///
  /*--cef()--*/
  virtual void OnProtocolExecution(CefRefPtr<CefBrowser> browser,
                                   const CefString& url,
                                   bool& allow_os_execution) {}

  ///
  // Called on the UI thread to handle requests for URLs with an invalid
  // SSL certificate. Return true and call CefRequestCallback::Continue() either
  // in this method or at a later time to continue or cancel the request. Return
  // false to cancel the request immediately. If
  // CefSettings.ignore_certificate_errors is set all invalid certificates will
  // be accepted without calling this method.
  ///
  /*--cef()--*/
  virtual bool OnCertificateError(
      CefRefPtr<CefBrowser> browser,
      cef_errorcode_t cert_error,
      const CefString& request_url,
      CefRefPtr<CefSSLInfo> ssl_info,
      CefRefPtr<CefRequestCallback> callback) {
    return false;
  }

  ///
  // Called on the browser process UI thread when a plugin has crashed.
  // |plugin_path| is the path of the plugin that crashed.
  ///
  /*--cef()--*/
  virtual void OnPluginCrashed(CefRefPtr<CefBrowser> browser,
                               const CefString& plugin_path) {}

  ///
  // Called on the browser process UI thread when the render view associated
  // with |browser| is ready to receive/handle IPC messages in the render
  // process.
  ///
  /*--cef()--*/
  virtual void OnRenderViewReady(CefRefPtr<CefBrowser> browser) {}

  ///
  // Called on the browser process UI thread when the render process
  // terminates unexpectedly. |status| indicates how the process
  // terminated.
  ///
  /*--cef()--*/
  virtual void OnRenderProcessTerminated(CefRefPtr<CefBrowser> browser,
                                         TerminationStatus status) {}
};

#endif  // CEF_INCLUDE_CEF_REQUEST_HANDLER_H_

Answer 1

SimpleHandler不是从CefRequestHandler派生的。然而，在SimpleHandler中使用ReturnValue而没有CefRequestHandler限定符，其中函数实现中ReturnValue与CrefRequestHandler限定符一起使用。 - CrefRequestHandler :: ReturnValue SimpleHandler :: OnBeforeResourceLoad。

这意味着SimpleHandler的一个基类也声明了ReturnValue（并且与CrefRequestHandler声明不同），因此在定义中它使用基类值，并且在它使用CefRequestHandler的实现中导致不匹配。

将定义更改为以下。

virtual CefRequestHandler::ReturnValue OnBeforeResourceLoad(
      CefRefPtr<CefBrowser> browser,
      CefRefPtr<CefFrame> frame,
      CefRefPtr<CefRequest> request,
      CefRefPtr<CefRequestCallback> callback) OVERRIDE;