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我正在使用 IsolatedStorageSettings 在我的应用程序中存储密钥的联系人列表。但是应用程序只存储列表，直到应用程序处于活动状态（即从一个页面导航到另一个页面）。如果我退出应用程序并重新启动它，则找不到存储的密钥/联系人列表。在安装应用程序之前，如何永久保存应用程序的列表？这是我的视图模型的代码，我正在使用：

   public class ContactsViewModel : ViewModelBase
    {
        private static IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;
        private List<SavedContact> _SavedContactsList;
        public ContactsViewModel()
        {

            Contacts cons = new Contacts();
            cons.SearchAsync(String.Empty, FilterKind.None, null);
            cons.SearchCompleted += new EventHandler<ContactsSearchEventArgs>(OnContactSearchCompleted);
            SaveSavedContactsCommand = new RelayCommand(OnSaveSavedContacts);
        }


        private List<SavedContact> GetSavedContacts()
        {

            if (appSettings.Contains("SavedContacts"))
            {
                var savedContacts = (List<SavedContact>)appSettings["SavedContacts"];
                return savedContacts;
            }
            else
            {
                return new List<SavedContact>();
            }
        }
        public RelayCommand SaveSavedContactsCommand { get; set; }

        private void OnSaveSavedContacts()
        {
            if (!SavedContactsList.Any(x => x.IsSelected == true))
            {
                MessageBox.Show("Please select some contacts and then click on Save button.");
            }
            else
            {
                var selectedSavedContacts = SavedContactsList.Where(x => x.IsSelected == true).ToList();
                SavedContacts = selectedSavedContacts;
                MessageBox.Show("Emergency contact list added successfully.");

                App.RootFrame.GoBack();
            }
        }

        void OnContactSearchCompleted(object sender, ContactsSearchEventArgs e)
        {
            try
            {
                SavedContactsList = new List<SavedContact>();
                var allContacts = new List<Contact>(e.Results.Where(x => x.PhoneNumbers.Count() > 0).OrderBy(c => c.DisplayName));
                // var savedContacts = GetSavedContacts();
                var savedContacts = SavedContacts;
                foreach (Contact contact in allContacts)
                {
                    SavedContact SavedContact = new SavedContact() { Contact = contact };
                    if (savedContacts.Any(x => x.Contact.PhoneNumbers.ElementAt(0).PhoneNumber == contact.PhoneNumbers.ElementAt(0).PhoneNumber))
                    {
                        SavedContact.IsSelected = true;
                    }
                    else
                    {
                        SavedContact.IsSelected = false;
                    }
                    SavedContactsList.Add(SavedContact);
                }

            }
            catch (System.Exception ex)
            {
                MessageBox.Show("Error in retrieving contacts : " + ex.Message);
            }

        }

        [DataMember]
        public List<SavedContact> SavedContactsList
        {
            get { return _SavedContactsList; }
            set
            {
                _SavedContactsList = value;
                RaisePropertyChanged("SavedContactsList");
            }
        }
        private List<SavedContact> SavedContacts
        {
            get
            {
                if (appSettings.Contains("SavedContacts"))
                {
                    var savedContacts = (List<SavedContact>)appSettings["SavedContacts"];
                    return savedContacts;
                }
                else
                {
                    return new List<SavedContact>();
                }
            }
            set
            {
                appSettings["SavedContacts"] = value;
            }
        }


    }

SavedContact 类如下：

  [DataContract]
    public class SavedContact : INotifyPropertyChanged
    {
        public SavedContact() { }
        private bool _isSelected;
        private Contact _contact;

        [DataMember]
        public bool IsSelected
        {
            get
            {
                return _isSelected;
            }
            set
            {
                if (_isSelected != value)
                {
                    _isSelected = value;
                    OnPropertyChanged("IsSelected");
                }

            }
        }

        [DataMember]
        public Contact Contact
        {
            get
            {
                return _contact;
            }
            set
            {
                if (_contact != value)
                {
                    _contact = value;
                    OnPropertyChanged("Contact");
                }

            }
        }
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}

视图模型绑定到<toolKit: LongListMultiSelector />. 该功能就像，我从我的长列表多选器中选择一些联系人并将其保存在存储中以供以后重复使用。但是，如果我退出应用程序并重新启动它，savedContacts 将返回 null。当我在我的应用程序中浏览其他页面时，savedContacts 正在打印。如果我第一次保存列表，则在应用重新启动时 GetSavedContacts() 返回一个新列表。

4

2 回答 2

1

问题与IsolatedStorageSettings您的RelayCommand. 更详细地看问题在于Contact对象的序列化和反序列化。如果你将你的实现更新为下面的例子，你应该没问题。

public class ContactsViewModel : ViewModelBase
{
    private static IsolatedStorageSettings appSettings = IsolatedStorageSettings.ApplicationSettings;

    private List<UserContact> _contactList;

    public ContactsViewModel()
    {

        Contacts cons = new Contacts();
        cons.SearchAsync(String.Empty, FilterKind.None, null);
        cons.SearchCompleted += new EventHandler<ContactsSearchEventArgs>(OnContactSearchCompleted);
        SaveSavedContactsCommand = new RelayCommand(OnSaveSavedContacts);
    }

    public RelayCommand SaveSavedContactsCommand { get; private set; }

    private void OnSaveSavedContacts()
    {
        if (!Contacts.Any(x => x.IsSelected == true))
        {
            MessageBox.Show("Please select some contacts and then click on Save button.");
        }
        else
        {
            var selectedSavedContacts = Contacts.Where(x => x.IsSelected == true).Select(x => new SavedContact{ Name = x.Contact.DisplayName, PhoneNumber = x.Contact.PhoneNumbers.ElementAt(0).PhoneNumber}).ToList();
            SavedContacts = selectedSavedContacts;
            MessageBox.Show("Emergency contact list added successfully.");

            App.RootFrame.GoBack();
        }
    }

    void OnContactSearchCompleted(object sender, ContactsSearchEventArgs e)
    {
        try
        {
            Contacts = new List<UserContact>();
            var allContacts = new List<Contact>(e.Results.Where(x => x.PhoneNumbers.Count() > 0).OrderBy(c => c.DisplayName));

            foreach (Contact contact in allContacts)
            {
                UserContact SavedContact = new UserContact() { Contact = contact };
                if (SavedContacts.Any(x => x.PhoneNumber == contact.PhoneNumbers.ElementAt(0).PhoneNumber))
                {
                    SavedContact.IsSelected = true;
                }
                else
                {
                    SavedContact.IsSelected = false;
                }
                Contacts.Add(SavedContact);
            }

        }
        catch (System.Exception ex)
        {
            MessageBox.Show("Error in retrieving contacts : " + ex.Message);
        }

    }

    [DataMember]
    public List<UserContact> Contacts
    {
        get { return _contactList; }
        set
        {
            _contactList = value;
            RaisePropertyChanged("Contacts");
        }
    }

    public List<SavedContact> SavedContacts
    {
        get
        {
            if (appSettings.Contains("SavedContacts"))
            {
                var savedContacts = (List<SavedContact>)IsolatedStorageSettings.ApplicationSettings["SavedContacts"];
                return savedContacts;
            }
            else
            {
                return new List<SavedContact>();
            }
        }
        set
        {
            if (value != null)
            {
                IsolatedStorageSettings.ApplicationSettings["SavedContacts"] = value;
                IsolatedStorageSettings.ApplicationSettings.Save();
            }
        }
    }
}

public class SavedContact
{
    public string Name { get; set; }

    public string PhoneNumber { get; set; }
}

[DataContract]
public class UserContact : INotifyPropertyChanged
{
    public UserContact() { }
    private bool _isSelected;
    private Contact _contact;

    [DataMember]
    public bool IsSelected
    {
        get
        {
            return _isSelected;
        }
        set
        {
            if (_isSelected != value)
            {
                _isSelected = value;
                OnPropertyChanged("IsSelected");
            }

        }
    }

    [DataMember]
    public Contact Contact
    {
        get
        {
            return _contact;
        }
        set
        {
            if (_contact != value)
            {
                _contact = value;
                OnPropertyChanged("Contact");
            }

        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
}
于 2013-10-13T15:21:47.073 回答
0

添加到应用程序 IsolatedStorageSettings 的键/值对将一直保留，直到卸载应用程序或从字典中删除该项目。这适用于应用程序重新启动和设备开机和关机之间。

您的 SaveList 方法可以简化为下面的示例，因为它只需要在.Contains从设置字典中检索值时进行检查，因为如果找不到该条目，它将引发异常。

private void SaveList()
{
    appSettings["SavedContacts"] = urls;
}

或者，您可以使用属性来处理对 IsolatedStorageSettings 的所有访问，如下例所示：

private IList<Contact> Contacts
{
    get
    {
        return appSettings.Contains("SavedContacts") ? (List<Contact>)appSettings["SavedContacts"] : null;
    }
    set
    {
        appSettings["SavedContacts"] = value;
    }
}
于 2013-10-09T19:09:47.073 回答