Prism使用Options选项
Options是微软提供的选项模块，该模块依赖于容器使用。除了微软的IServiceCollection，当然也可以使用其它的依赖注入容器。本文演示如何在prism中使用Options。创建应用项目
创建一个Avalonia应用（或其它类型应用），然后使用NuGet包管理器添加Prism.DryIoc.Avalonia包。创建Views和ViewModels文件夹，将MainWindow移动到Views文件夹中（注意修改namespace），在ViewModels文件夹中创建MainWindowViewModel，以便Prism自动绑定ViewModel。
public partial class App : PrismApplication
{
public override void Initialize()
{
AvaloniaXamlLoader.Load(this);
base.Initialize();
}
protected override AvaloniaObject CreateShell()
{
return Container.Resolve<MainWindow>();
}
protected override void RegisterTypes(IContainerRegistry containerRegistry)
{
containerRegistry.Register<MainWindow>();
}
}添加Options功能
[*]首先使用NuGet添加Microsoft.Extentions.Options和Microsoft.Extensions.Options.ConfigurationExtensions。使用json配置文件进行测试，因此再添加上Microsoft.Extensions.Configuration.Json及Microsoft.Extensions.Configuration.Binder。
[*]添加Options静态类，提供DefaultName：
public static class Options
{
public static readonly string DefaultName = string.Empty;
internal const DynamicallyAccessedMemberTypes DynamicallyAccessedMembers =
DynamicallyAccessedMemberTypes.PublicParameterlessConstructor;
}
[*]由于UnnamedOptionsManager为内部类，无法直接使用，因此添加一个UnnamedOptionsManager类，实现IOptions接口，直接拷贝源码即可：
public class UnnamedOptionsManager< TOptions> :
IOptions<TOptions>
where TOptions : class
{
private readonly IOptionsFactory<TOptions> _factory;
private volatile object _syncObj;
private volatile TOptions _value;
public UnnamedOptionsManager(IOptionsFactory<TOptions> factory) => _factory = factory;
public TOptions Value
{
get
{
if (_value is TOptions value)
return value;
lock (_syncObj ?? Interlocked.CompareExchange(ref _syncObj, new object(), null) ?? _syncObj)
{
return _value ??= _factory.Create(Options.DefaultName);
}
}
}
}
[*]添加OptionsPrismExtensions扩展类，添加AddOptions扩展方法，将选项泛型接口、工厂、缓存注册到容器中。工厂注册为瞬时，其它注册为单例。客户端不需要添加IOptionsSnapshot，只添加IOptions和IOptionsMonitor即可，前者获取选项不会监听修改，后者可以监听选项修改：
public static class OptionsPrismExtensions
{
public static IContainerExtension AddOptions(this IContainerExtension container)
{
ArgumentNullException.ThrowIfNull(container, nameof(container));
container.RegisterSingleton(typeof(IOptions<>), typeof(UnnamedOptionsManager<>));
container.RegisterSingleton(typeof(IOptionsMonitor<>), typeof(OptionsMonitor<>));
container.Register(typeof(IOptionsFactory<>), typeof(OptionsFactory<>));
container.RegisterSingleton(typeof(IOptionsMonitorCache<>), typeof(OptionsCache<>));
return container;
}
}
[*]添加OptionsConfigurationPrismExtensions扩展类，提供Configuration相关的扩展方法，可以直接将选项和配置Section进行绑定：
public static class OptionsConfigurationPrismExtensions
{
public static IContainerExtension Configure<[DynamicallyAccessedMembers(
DynamicallyAccessedMemberTypes.All)] TOptions>(this IContainerExtension container,
IConfiguration config) where TOptions : class
=> container.Configure<TOptions>(Options.DefaultName, config, _ => { });
public static IContainerExtension Configure<[DynamicallyAccessedMembers(
DynamicallyAccessedMemberTypes.All)] TOptions>(this IContainerExtension container,
string name, IConfiguration config, Action<BinderOptions> configureBinder)
where TOptions : class
{
ArgumentNullException.ThrowIfNull(container, nameof(container));
ArgumentNullException.ThrowIfNull(config, nameof(config));
container.AddOptions();
container.RegisterInstance<IOptionsChangeTokenSource<TOptions>>(
new ConfigurationChangeTokenSource<TOptions>(name, config));
container.RegisterInstance<IConfigureOptions<TOptions>>(
new NamedConfigureFromConfigurationOptions<TOptions>(name, config, configureBinder));
return container;
}
}使用
[*]添加一个settings.json配置文件，设置属性复制到输出目录：如果较新则复制：
{
"Test": {
"Name": "louzi",
"Age": 18,
"Sex": "Male"
}
}
[*]添加Test对应的Option实体：
public class TestOption
{
public string Name { get; set; }
public int Age { get; set; }
public Gender Sex { get; set; }
}
public enum Gender
{
Male,
Female
}
[*]创建IConfiguration并绑定到选项：
// App
protected override IContainerExtension CreateContainerExtension()
{
var container =base.CreateContainerExtension();
IConfiguration config = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("settings.json", optional: true, reloadOnChange: true).Build();
container.AddOptions().Configure<TestOption>(config.GetSection("Test"));
return container;
}
[*]ViewModel中通过依赖注入获取选项：
public class MainWindowViewModel : BindableBase
{
private string _name;
private int _age;
private Gender _sex;
public MainWindowViewModel(IOptions<TestOption> options)
{
var testOption = options.Value;
_name = testOption.Name;
_age = testOption.Age;
_sex = testOption.Sex;
}
public string Name { get => _name; set => SetProperty(ref _name, value); }
public int Age { get => _age; set => SetProperty(ref _age, value); }
public Gender Sex { get => _sex; set => SetProperty(ref _sex, value); }
}
[*]View中显示
<Grid RowDefinitions="1*,1*,1*" ColumnDefinitions="1*,1*">
<TextBlock Text="Name: " TextAlignment="Right"/>
<TextBlock Text="{Binding Name}" Grid.Column="1"/>
<TextBlock Text="Age: " Grid.Row="1" TextAlignment="Right"/>
<TextBlock Text="{Binding Age}" Grid.Row="1" Grid.Column="1"/>
<TextBlock Text="Sex: " Grid.Row="2" TextAlignment="Right"/>
<TextBlock Text="{Binding Sex}" Grid.Row="2" Grid.Column="1"/>
</Grid>项目结构及运行效果如下图：
来源:https://www.cnblogs.com/louzixl/archive/2023/12/05/17877961.html
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