在WPF中使用.NET Core 3.0依赖项注入和服务提供程序

前言

我们都知道.NET Core提供了对依赖项注入的内置支持。我们通常在ASP.NET Core中使用它(从Startup.cs文件中的ConfigureServices方法开始),但是该功能不限于此框架,我们可以在WPF和Windows Forms应用程序中使用它。

实践

  1. 新建项目

    1572333532.jpg

  2. 将所需的NuGet包添加到项目中。

    • Microsoft.Extensions.DependencyInjection
    • Microsoft.Extensions.Options.ConfigurationExtensions
    • Microsoft.Extensions.Configuration.Json
      1572334178_1_.jpg
  3. 然后,将一个名为appsettings.json的文件添加到项目的根文件夹。将其“ 构建操作”属性设置为“ 内容”,将“复制到输出目录”设置为“ 复制”(如果较新):

    {
    "AppSettings": {
        "AppName": "SampleNetCore3WpfDependencyInjection"
        }
    }
    
  4. 创建一个AppSettings.cs文件来保存配置设置。该文件将映射我们在appsettings.json中编写的设置:

    public class AppSettings
        {
            public string AppName { get; set; } 
        }
    
  5. 创建一个示例服务:

    public interface ISampleService
        {
            Task<string> GetCurrentDate();
        }
    
    public class SampleService : ISampleService
        {
            public async Task<string> GetCurrentDate() => 
            await Task.FromResult(DateTime.Now.ToLongDateString());
        }
    

    然后像往常一样在IOC容器中注册服务:

    services.AddScoped<ISampleService, SampleService>();
    
    
  6. 打开App.xaml文件并删除Application类的StartupUri属性。然后,我们需要重写App.xaml.cs中的OnStartup方法:

    public partial class App : Application
        {
            public IServiceProvider ServiceProvider { get; private set; }
            public IConfiguration Configuration { get; private set; }
    
            protected override void OnStartup(StartupEventArgs e)
            {
                var builder = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
    
                Configuration = builder.Build();
    
                var serviceCollection = new ServiceCollection();
                ConfigureServices(serviceCollection);
    
                ServiceProvider = serviceCollection.BuildServiceProvider();
    
                var mainWindow = ServiceProvider.GetRequiredService<MainWindow>();
                mainWindow.Show();
            }
    
            private void ConfigureServices(IServiceCollection services)
            {
                services.Configure<AppSettings>(Configuration.GetSection(nameof(AppSettings)));
                services.AddScoped<ISampleService, SampleService>();
                services.AddTransient(typeof(MainWindow));
            }
        }
    
  7. MainWindow简单布局及代码改造

    如上所述,MainWindow位于IOC容器中。因此,当我们从服务提供商处获得服务时,它将自动注入所有必需的服务(如果有)。:

    public partial class MainWindow : Window
        {
            private readonly ISampleService sampleService;
            private readonly AppSettings settings;
    
            public MainWindow(ISampleService sampleService,
                IOptions<AppSettings> settings)
            {
                InitializeComponent();
    
                this.sampleService = sampleService;
                this.settings = settings.Value;
            }
    
            private async void Button_Click(object sender, RoutedEventArgs e)
            {
                var serviceData =await sampleService.GetCurrentDate();
                var settingsData = settings;
                TextBox1.Text = $"serviceData:{serviceData}{Environment.NewLine}settingsData:{settings.AppName}";
            }
        }
    
    

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  8. Demo地址:github

posted @ 2019-10-29 17:03  WalterGao  阅读(1175)  评论(4编辑  收藏