我正在开发通用Windows平台应用程序,但Visual Studio中没有“设置”模板。

如何实现一个简单的,类型强且可观察的类,将我的设置存储在LocalSettings或RoamingSettings中?

最佳答案

  • 创建一个新的类,该类继承自ObservableSettings。
  • 调用基类构造函数,以指示是要将设置存储在 LocalSettings 还是 RoamingSettings 中。
  • 添加所有调用基类成员的属性
    设置在getter和setter中获取。无需传递属性名称或使用 nameof()运算符!
  • (可选)您可以设置一个默认值,以 DefaultSettingValue 属性装饰该属性。

  • 这里是一个设置类的例子:
    namespace Test
    {
        public class Settings : ObservableSettings
        {
            private static Settings settings = new Settings();
            public static Settings Default
            {
                get { return settings; }
            }
    
            public Settings()
                : base(ApplicationData.Current.LocalSettings)
            {
            }
    
            [DefaultSettingValue(Value = 115200)]
            public int Bauds
            {
                get { return Get<int>(); }
                set { Set(value); }
            }
    
            [DefaultSettingValue(Value = "Jose")]
            public string Name
            {
                get { return Get<string>(); }
                set { Set(value); }
            }
    
        }
    }
    

    以及如何在您的app.xaml中添加实例:
    <Application
        x:Class="Test.App"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Test"
        RequestedTheme="Light">
        <Application.Resources>
            <local:Settings x:Key="settings"/>
        </Application.Resources>
    </Application>
    

    以MVVM方式访问和修改值:
    <Page
        x:Class="Test.MainPage"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:Test"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d"
        DataContext="{StaticResource settings}">
    
        <StackPanel Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
            <TextBlock Text="Bauds"/>
            <TextBox Text="{Binding Default.Bauds, Mode=TwoWay}"/>
            <TextBlock Text="Name"/>
            <TextBox Text="{Binding Default.Name, Mode=TwoWay}"/>
        </StackPanel>
    </Page>
    

    一切都将正确存储在您的设置存储库中。

    在这里,您可以实现 DefaultSettingValue ObservableSettings 的实现:
    using System.Collections.Generic;
    using System.Linq;
    using System.Runtime.CompilerServices;
    using System.Reflection;
    using System.ComponentModel;
    using Windows.Storage;
    
    
    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
    public sealed class DefaultSettingValueAttribute : Attribute
    {
        public DefaultSettingValueAttribute()
        {
        }
    
        public DefaultSettingValueAttribute(object value)
        {
            Value = value;
        }
    
        public object Value { get; set; }
    }
    
    public class ObservableSettings : INotifyPropertyChanged
    {
        private readonly ApplicationDataContainer settings;
    
        public ObservableSettings(ApplicationDataContainer settings)
        {
            this.settings = settings;
        }
    
        public event PropertyChangedEventHandler PropertyChanged;
    
        protected bool Set<T>(T value, [CallerMemberName] string propertyName = null)
        {
            if (settings.Values.ContainsKey(propertyName))
            {
                var currentValue = (T)settings.Values[propertyName];
                if (EqualityComparer<T>.Default.Equals(currentValue, value))
                    return false;
            }
    
            settings.Values[propertyName] = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            return true;
        }
    
        protected T Get<T>([CallerMemberName] string propertyName = null)
        {
            if (settings.Values.ContainsKey(propertyName))
                return (T)settings.Values[propertyName];
    
            var attributes = GetType().GetTypeInfo().GetDeclaredProperty(propertyName).CustomAttributes.Where(ca => ca.AttributeType == typeof(DefaultSettingValueAttribute)).ToList();
            if (attributes.Count == 1)
                return (T)attributes[0].NamedArguments[0].TypedValue.Value;
    
            return default(T);
        }
    

    您可以从GitHub中创建的存储库中下载带有功能示例的解决方案。

    10-05 23:02
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