C# Frame.SetValue方法代码示例

        /// <summary>
        /// Registers a <see cref="Frame"/> instance to allow its navigation history to be saved to
        /// and restored from <see cref="SessionState"/>.  Frames should be registered once
        /// immediately after creation if they will participate in session state management.  Upon
        /// registration if state has already been restored for the specified key
        /// the navigation history will immediately be restored.  Subsequent invocations of
        /// <see cref="RestoreAsync"/> will also restore navigation history.
        /// </summary>
        /// <param name="frame">An instance whose navigation history should be managed by
        /// <see cref="SuspensionManager"/></param>
        /// <param name="sessionStateKey">A unique key into <see cref="SessionState"/> used to
        /// store navigation-related information.</param>
        /// <param name="sessionBaseKey">An optional key that identifies the type of session.
        /// This can be used to distinguish between multiple application launch scenarios.</param>
        public static void RegisterFrame(Frame frame, String sessionStateKey, String sessionBaseKey = null)
        {
            if (frame.GetValue(FrameSessionStateKeyProperty) != null)
            {
                throw new InvalidOperationException("Frames can only be registered to one session state key");
            }

            if (frame.GetValue(FrameSessionStateProperty) != null)
            {
                throw new InvalidOperationException("Frames must be either be registered before accessing frame session state, or not registered at all");
            }

            if (!string.IsNullOrEmpty(sessionBaseKey))
            {
                frame.SetValue(FrameSessionBaseKeyProperty, sessionBaseKey);
                sessionStateKey = sessionBaseKey + "_" + sessionStateKey;
            }

            // Use a dependency property to associate the session key with a frame, and keep a list of frames whose
            // navigation state should be managed
            frame.SetValue(FrameSessionStateKeyProperty, sessionStateKey);
            _registeredFrames.Add(new WeakReference<Frame>(frame));

            // Check to see if navigation state can be restored
            RestoreFrameNavigationState(frame);
        }

        /// <summary>
        /// Provides storage for session state associated with the specified <see cref="Frame"/>.
        /// Frames that have been previously registered with RegisterFrame have
        /// their session state saved and restored automatically as a part of the global
        /// SessionState.  Frames that are not registered have transient state
        /// that can still be useful when restoring pages that have been discarded from the
        /// navigation cache.
        /// </summary>
        /// <remarks>Apps may choose to rely on <see cref="LayoutAwarePage"/> to manage
        /// page-specific state instead of working with frame session state directly.</remarks>
        /// <param name="frame">The instance for which session state is desired.</param>
        /// <returns>A collection of state subject to the same serialization mechanism as
        /// SessionState.</returns>
        public static Dictionary<String, Object> SessionStateForFrame(Frame frame)
        {
            var frameState = (Dictionary<String, Object>)frame.GetValue(FrameSessionStateProperty);

            if (frameState == null)
            {
                var frameSessionKey = (String)frame.GetValue(FrameSessionStateKeyProperty);
                if (frameSessionKey != null)
                {
                    // Registered frames reflect the corresponding session state
                    if (!SessionState.ContainsKey(frameSessionKey))
                    {
                        SessionState[frameSessionKey] = new Dictionary<String, Object>();
                    }
                    frameState = (Dictionary<String, Object>)SessionState[frameSessionKey];
                }
                else
                {
                    // Frames that aren't registered have transient state
                    frameState = new Dictionary<String, Object>();
                }
                frame.SetValue(FrameSessionStateProperty, frameState);
            }
            return frameState;
        }

        public static void RegisterFrame(Frame frame, string sessionStateKey, string sessionBaseKey = null)
        {
            if (frame.GetValue(FrameSessionStateKeyProperty) != null)
            {
                throw new InvalidOperationException("Frames can only be registered to one session state key");
            }

            if (frame.GetValue(FrameSessionStateProperty) != null)
            {
                throw new InvalidOperationException("Frames must be either be registerd before accessing frame session staet, or not registered at all");
            }

            if (!string.IsNullOrEmpty(sessionBaseKey))
            {
                frame.SetValue(FrameSessionBaseKeyProperty, sessionBaseKey);
                sessionStateKey = sessionStateKey + "_" + sessionStateKey;
            }

            frame.SetValue(FrameSessionStateKeyProperty, sessionStateKey);
            _registeredFrames.Add(new WeakReference<Frame>(frame));

            RestoreFrameNavigationState(frame);
        }

        /// <summary>
        /// 为与指定的 <see cref="Frame"/> 相关联的会话状态提供存储。
        /// 之前已向 <see cref="RegisterFrame"/> 注册的框架已自动
        /// 保存其会话状态且还原为全局
        /// <see cref="SessionState"/> 的一部分。  未注册的框架具有
        /// 在还原已从导航缓存中丢弃的页面时仍然有用的
        /// 导航缓存。
        /// </summary>
        /// <remarks>应用程序可能决定依靠 <see cref="NavigationHelper"/> 管理
        /// 特定于页面的状态，而非直接使用框架会话状态。</remarks>
        /// <param name="frame">需要会话状态的实例。</param>
        /// <returns>状态集合受限于与
        /// <see cref="SessionState"/>。</returns>
        public static Dictionary<String, Object> SessionStateForFrame(Frame frame)
        {
            var frameState = (Dictionary<String, Object>)frame.GetValue(FrameSessionStateProperty);

            if (frameState == null)
            {
                var frameSessionKey = (String)frame.GetValue(FrameSessionStateKeyProperty);
                if (frameSessionKey != null)
                {
                    // 已注册框架反映相应的会话状态
                    if (!_sessionState.ContainsKey(frameSessionKey))
                    {
                        _sessionState[frameSessionKey] = new Dictionary<String, Object>();
                    }
                    frameState = (Dictionary<String, Object>)_sessionState[frameSessionKey];
                }
                else
                {
                    // 未注册框架具有瞬时状态
                    frameState = new Dictionary<String, Object>();
                }
                frame.SetValue(FrameSessionStateProperty, frameState);
            }
            return frameState;
        }

        /// <summary>
        /// 注册 <see cref="Frame"/> 实例以允许将其导航历史记录保存到
        /// <see cref="SessionState"/> 并从中还原。如果框架将参与会话状态管理，
        /// 则应在创建框架后立即注册。在
        /// 注册时，如果已还原指定键的状态，
        /// 则将立即还原导航历史记录。
        /// <see cref="RestoreAsync"/> 还将还原导航历史记录。
        /// </summary>
        /// <param name="frame">其导航历史记录应由
        /// <see cref="SuspensionManager"/></param>
        /// <param name="sessionStateKey"><see cref="SessionState"/> 的唯一键，用于
        /// 存储与导航相关的信息。</param>
        public static void RegisterFrame(Frame frame, String sessionStateKey)
        {
            if (frame.GetValue(FrameSessionStateKeyProperty) != null)
            {
                throw new InvalidOperationException("Frames can only be registered to one session state key");
            }

            if (frame.GetValue(FrameSessionStateProperty) != null)
            {
                throw new InvalidOperationException("Frames must be either be registered before accessing frame session state, or not registered at all");
            }

            // 使用依赖项属性可会话键与框架相关联，并记录其
            // 导航状态应托管的框架
            frame.SetValue(FrameSessionStateKeyProperty, sessionStateKey);
            _registeredFrames.Add(new WeakReference<Frame>(frame));

            // 查看导航状态是否可还原
            RestoreFrameNavigationState(frame);
        }

        /// <summary>
        /// Provides storage for session state associated with the specified <see cref="Frame"/>.
        /// Frames that have been previously registered with <see cref="RegisterFrame"/> have
        /// their session state saved and restored automatically as a part of the global
        /// <see cref="SessionState"/>.  Frames that are not registered have transient state
        /// that can still be useful when restoring pages that have been discarded from the
        /// navigation cache.
        /// </summary>
        /// <remarks>Apps may choose to rely on <see cref="NavigationHelper"/> to manage
        /// page-specific state instead of working with frame session state directly.</remarks>
        /// <param name="frame">The instance for which session state is desired.</param>
        /// <returns>A collection of state subject to the same serialization mechanism as
        /// <see cref="SessionState"/>.</returns>
        public static Dictionary<String, Object> SessionStateForFrame(Frame frame)
        {
            var frameState = (Dictionary<String, Object>)frame.GetValue(FrameSessionStateProperty);

            if (frameState == null)
            {
                var frameSessionKey = (String)frame.GetValue(FrameSessionStateKeyProperty);
                if (frameSessionKey != null)
                {
                    // Registered frames reflect the corresponding session state
                    if (!_sessionState.ContainsKey(frameSessionKey))
                        _sessionState[frameSessionKey] = Json.Instance.Serialize(new Dictionary<String, Object>());

                    frameState = Json.Instance.Deserialize<Dictionary<String, Object>>(_sessionState[frameSessionKey].ToString());
                    //frameState = (Dictionary<String, Object>);
                }
                else
                {
                    // Frames that aren't registered have transient state
                    frameState = new Dictionary<String, Object>();
                }
                frame.SetValue(FrameSessionStateProperty, frameState);
            }
            return frameState;
        }

    /// <summary>
    /// Registriert eine <see cref="Frame"/>-Instanz, um den zugehörigen Navigationsverlauf mithilfe von
    /// <see cref="SessionState"/> speichern und wiederherstellen zu können.  Rahmen sollten direkt nach der Erstellung
    /// registriert werden, wenn diese Bestandteil der Verwaltung des Sitzungszustands sind.  Wenn der
    /// Zustand für den speziellen Schlüssel bereits wiederhergestellt wurde,
    /// wird der Navigationsverlauf bei der Registrierung sofort wiederhergestellt.  Bei nachfolgenden Aufrufen von
    /// <see cref="RestoreAsync"/> wird der Navigationsverlauf ebenfalls wiederhergestellt.
    /// </summary>
    /// <param name="frame">Eine Instanz, deren Navigationsverlauf von
    /// <see cref="SuspensionManager"/></param>
    /// <param name="sessionStateKey">Ein eindeutiger Schlüssel in <see cref="SessionState"/> zum
    /// Speichern von navigationsbezogenen Informationen.</param>
    /// <param name="sessionBaseKey">Ein optionaler Schlüssel zum Identifizieren des Typs der Sitzung.
    /// Damit können verschiedene Szenarien für den Anwendungsstart unterschieden werden.</param>
    public static void RegisterFrame(Frame frame, String sessionStateKey, String sessionBaseKey = null)
    {
      if (frame.GetValue(FrameSessionStateKeyProperty) != null)
      {
        throw new InvalidOperationException("Frames can only be registered to one session state key");
      }

      if (frame.GetValue(FrameSessionStateProperty) != null)
      {
        throw new InvalidOperationException("Frames must be either be registered before accessing frame session state, or not registered at all");
      }

      if (!string.IsNullOrEmpty(sessionBaseKey))
      {
        frame.SetValue(FrameSessionBaseKeyProperty, sessionBaseKey);
        sessionStateKey = sessionBaseKey + "_" + sessionStateKey;
      }

      // Eine Abhängigkeitseigenschaft verwenden, um den Sitzungsschlüssel mit einem Rahmen zu verknüpfen, und eine Liste von Rahmen speichern, deren
      // Navigationszustand verwaltet werden soll
      frame.SetValue(FrameSessionStateKeyProperty, sessionStateKey);
      _registeredFrames.Add(new WeakReference<Frame>(frame));

      // Überprüfen, ob der Navigationszustand wiederhergestellt werden kann
      RestoreFrameNavigationState(frame);
    }

        public static Dictionary<string, object> SessionStateForFrame(Frame frame)
        {
            var frameState = (Dictionary<string, object>)frame.GetValue(mFrameSessionStateProperty);
            if (frameState == null)
            {
                var frameSessionKey = (string)frame.GetValue(mFrameSessionStateKeyProperty);
                if (frameSessionKey != null)
                {
                    if (!mSessionState.ContainsKey(frameSessionKey))
                    {
                        mSessionState[frameSessionKey] = new Dictionary<string, object>();
                    }
                    frameState = (Dictionary<string, object>)mSessionState[frameSessionKey];
                }
                else
                {
                    frameState = new Dictionary<string, object>();
                }
                frame.SetValue(mFrameSessionStateProperty, frameState);
            }

            return frameState;
        }

    /// <summary>
    /// Bietet Speichermöglichkeit für den Sitzungszustand, der mit dem angegebenen <see cref="Frame"/> verknüpft ist.
    /// Für Rahmen, die zuvor mit <see cref="RegisterFrame"/> registriert wurden, wird der
    /// Sitzungszustand automatisch als Teil des globalen <see cref="SessionState"/>
    /// gespeichert und wiederhergestellt.  Rahmen, die nicht registriert sind, verfügen über einen vorübergehenden Zustand,
    /// der weiterhin nützlich sein kann, wenn Seiten wiederhergestellt werden, die aus dem
    /// im Navigationscache verworfen wird.
    /// </summary>
    /// <remarks>Apps können beim Verwalten des seitenspezifischen Zustands auf <see cref="NavigationHelper"/> zurückgreifen,
    /// anstatt direkt mit dem Rahmensitzungszustand zu arbeiten.</remarks>
    /// <param name="frame">Die Instanz, für die der Sitzungszustand gewünscht wird.</param>
    /// <returns>Eine Auflistung des Zustands, für den der gleiche Serialisierungsmechanismus wie für
    /// <see cref="SessionState"/>.</returns>
    public static Dictionary<String, Object> SessionStateForFrame(Frame frame)
    {
      var frameState = (Dictionary<String, Object>)frame.GetValue(FrameSessionStateProperty);

      if (frameState == null)
      {
        var frameSessionKey = (String)frame.GetValue(FrameSessionStateKeyProperty);
        if (frameSessionKey != null)
        {
          // Registrierte Rahmen geben den entsprechenden Sitzungszustand wieder.
          if (!_sessionState.ContainsKey(frameSessionKey))
          {
            _sessionState[frameSessionKey] = new Dictionary<String, Object>();
          }
          frameState = (Dictionary<String, Object>)_sessionState[frameSessionKey];
        }
        else
        {
          // Rahmen, die nicht registriert sind, verfügen über einen vorübergehenden Zustand
          frameState = new Dictionary<String, Object>();
        }
        frame.SetValue(FrameSessionStateProperty, frameState);
      }
      return frameState;
    }