IsolatedStorage 在应用重启 WP7 后不保存列表 <MyObject>

Question

我正在开发一个应用程序，我需要在其中保存 ExerciseObject 类型的对象列表。我不明白为什么在应用程序重新启动后此数据没有保留在 IsolatedStorageSettings 中，而我的所有其他数据（包括我创建的其他对象）。

这是 ExerciseObject class，我在其中创建了一个列表，其中包含要存储到 IsolatedStorageSettings 的此对象类型。有趣的是，当应用程序打开时，数据被保存了，只是一旦我重新启动应用程序，只有 ExerciseObject 数据列表丢失了。

public class ExerciseObject
{
    public ExerciseObject(string description, int caloriesBurned, bool burned)
    {
        this.Description = description;
        this.CaloriesBurned = caloriesBurned;
        this.Burned = burned; // true if activity, false if food

        if (this.Burned) // text should be green
            this.TextColor = new SolidColorBrush(Colors.Green);
        else
            this.TextColor = new SolidColorBrush(Colors.Red);
    }

    public string Description { get; set; }
    public int CaloriesBurned { get; set; }
    public bool Burned { get; set; }
    public SolidColorBrush TextColor { get; set; }
}

这就是我添加到列表中的方式：

    ExerciseObject exerciseObj = new ExerciseObject(this.txtActivity.Text, int.Parse(this.txtBurned.Text), true);
    List<ExerciseObject> tempList = (List<ExerciseObject>)IsolatedStorageSettings.ApplicationSettings["ListExerciseObjects"];
    tempList.Add(exerciseObj);
    IsolatedStorageSettings.ApplicationSettings["ListExerciseObjects"] = tempList;

这就是我访问列表的方式：

        // Get the list of exercise objects from the isolated storage
        List<ExerciseObject> exerciseObjects = (List<ExerciseObject>)IsolatedStorageSettings.ApplicationSettings["ListExerciseObjects"];       

        // Setting data context of listBox to the list of exercise objects for now
        this.listBoxEntries.DataContext = exerciseObjects;

Answer 1

我试过你的例子，SolidColorBrush 类型似乎不可序列化。当应用程序存在时，phone 内部调用 iso storage "Save" 方法，但它会静默失败。要重现，删除 TextColor 属性或在属性上应用 "IgnoreDataMemberAttribute" 并观察问题是否消失。

有多种方法可以解决这个问题。我个人会从您的 "burned" 属性中推导出在运行时应用的画笔类型。

我附上了您的代码的工作示例，如果您仍然希望存储它，它现在存储实际颜色而不是 SolidColorBrush 对象。

Main.cs

// Constructor
    public MainPage()
    {
        InitializeComponent();

        BindExercises();
    }

    private void AddExercise(object sender, RoutedEventArgs e)
    {
        var exercise = new ExerciseObject("Activity added at: " + DateTime.Now.Ticks, (DateTime.Now.Second + 200), true);

        IsolatedStorageSettingsManager.AddToCollection("ListExerciseObjects", exercise);

        this.BindExercises();
    }

    private void BindExercises()
    {
        // Setting data context of listBox to the list of exercise objects for now
        this.listBoxEntries.ItemsSource = IsolatedStorageSettingsManager.Get<IEnumerable<ExerciseObject>>("ListExerciseObjects").ToObservableCollection();
    }

    private void RemoveAllExercises(object sender, RoutedEventArgs e)
    {
        IsolatedStorageSettingsManager.Remove("ListExerciseObjects");

        this.BindExercises();
    }

public static class EnumerableExtensions
{
    public static ObservableCollection<T> ToObservableCollection<T>(this IEnumerable<T> myList)
    {
        if (myList == null) return null;

        var oc = new ObservableCollection<T>();
        foreach (var item in myList)
            oc.Add(item);
        return oc;
    }
}

public class ExerciseObject
{
    public ExerciseObject() { }

    public ExerciseObject(string description, int caloriesBurned, bool burned)
    {
        this.Description = description;
        this.CaloriesBurned = caloriesBurned;
        this.Burned = burned; // true if activity, false if food

        if (this.Burned) // text should be green
            this.Color = Colors.Green;
        else
            this.Color = Colors.Red;
    }

    public string Description { get; set; }
    public int CaloriesBurned { get; set; }
    public bool Burned { get; set; }

    public Color Color { get; set; }

    [IgnoreDataMemberAttribute]
    public SolidColorBrush TextColor
    {
        get
        {
            return new SolidColorBrush(this.Color);
        }
    }
}

public class IsolatedStorageSettingsManager
{
    private static readonly IsolatedStorageSettings isolatedStorageSettings = IsolatedStorageSettings.ApplicationSettings;

    public static void Add<T>(string key, T value)
    {
        if (isolatedStorageSettings.Contains(key))
        {
            isolatedStorageSettings[key] = value;
        }
        else
        {
            isolatedStorageSettings.Add(key, value);

        }

        Save();
    }

    public static T Get<T>(string key, T @default = default(T))
    {
        T value;

        if (isolatedStorageSettings.TryGetValue(key, out value))
        {
            return value;
        }

        return @default; // TODO: tell it what to do if the key is not found.
    }

    /// <summary>
    /// Special [very crude] method which handles collections.
    /// </summary>
    /// <typeparam name="T">
    /// The type of object to be serialized.
    /// </typeparam>
    /// <param name="key">
    /// The key to assign to the object.
    /// </param>
    /// <param name="newValue">
    /// The new record to add.
    /// </param>
    /// <returns>
    /// The newly updated collection.
    /// </returns>
    public static IEnumerable<T> AddToCollection<T>(string key, T newValue) where T : class 
    {
        List<T> currentValues;

        if (isolatedStorageSettings.Contains(key))
        {
            currentValues = isolatedStorageSettings[key] as List<T>;

            if (currentValues == null)
            {
                throw new InvalidCastException("The current values in the isolated storage settings " + key + "is not of a valid type");
            }

            currentValues.Add(newValue);
            isolatedStorageSettings[key] = currentValues;
        }
        else
        {
            currentValues = new List<T> { newValue };
            isolatedStorageSettings.Add(key, currentValues);
        }

        Save();

        return currentValues;
    }

    public static void Remove(string key)
    {
        if (isolatedStorageSettings.Contains(key))
        {
            isolatedStorageSettings.Remove(key);
            Save();
        }
    }

    private static void Save()
    {
        isolatedStorageSettings.Save();
    }
}

Xaml

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Button Content="Add Exercise" Click="AddExercise" />
        <Button Grid.Row="1" Content="Clear All" Click="RemoveAllExercises" />

        <ListBox x:Name="listBoxEntries" Grid.Row="2">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Description }" />
                        <TextBlock Margin="15 0 0 0" Text="{Binding CaloriesBurned }" Foreground="{Binding TextColor}" />
                    </StackPanel>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>
    </Grid>

IsolatedStorage 在应用重启 WP7 后不保存列表 <MyObject>

IsolatedStorage not saving List<MyObject> after app restart WP7

list

windows-phone-7

save

isolatedstorage

persist