ASP.NET 8 – 多语言应用程序（单 Resx 文件）– 第 2 部分 – 替代方法

Mark Pelf

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2024年3月13日

CPOL

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如何构建多语言 ASP.NET 8 MVC 应用程序

下载源代码 - 1.6 MB

1. 上篇文章解决方案的变体

在本文中，我们展示了一种在之前关于如何解决只有一个 Resx 文件语言字符串问题的文章中的解决方案的变体。我们展示此变体是因为它在互联网上是一种流行的方法（参见 [7]、[8]、[9]），尽管基本工作原理与上一篇文章相同。这种方法可以看作是使用辅助/包装器对象来实现相同的结果。

我个人更喜欢上一篇文章中的直接方法，但这种方法在互联网上相当流行，所以由开发人员根据自己的偏好选择。

2. 系列文章

本系列文章包括：

3. 共享资源方法

默认情况下，ASP.NET Core 8 MVC 技术为每个控制器和视图都预留了单独的资源文件 .resx。但大多数人不喜欢这样做，因为应用程序的不同地方的大多数多语言字符串都相同，我们希望将它们放在同一个地方。文献 [1] 将这种方法称为“共享资源”方法。为了实现它，我们将创建一个标记类 SharedResources.cs 来 agrupir 所有资源。

然后在我们的应用程序中，我们使用一个工厂函数来创建一个专注于该类/类型的 StringLocalizer 服务，并将其包装到名为 SharedStringLocalizer 的辅助对象中。

然后，在我们的应用程序中，我们将使用依赖注入 (DI) 将该包装器对象/服务注入到需要本地化服务的 메서드 中。

与本系列上一篇文章的解决方案相比，主要区别在于，我们不是直接通过 DI 注入 IStringLocalizer<SharedResource>，而是将其包装到辅助对象 SharedStringLocalizer 中，然后注入该辅助对象。其工作原理的基本原理是相同的。

4. 多语言应用程序步骤

4.1 创建标记类 SharedResources.cs

这只是一个用于 agrupir 共享资源的虚拟标记类。我们需要它是因为它的名称和类型。

似乎命名空间需要与应用程序的根命名空间相同，而根命名空间需要与程序集名称相同。我在更改命名空间时遇到了一些问题，它不起作用。

SharedResource 这个名字并没有什么特别之处，你可以将其命名为 MyResources，并在代码中更改所有对 MyResources 的引用，一切仍然会正常工作。

位置似乎可以是任何文件夹，尽管一些文章（[6]）声称它需要位于项目根文件夹。在此示例中我没有看到此类问题。对我来说，它似乎可以是任何文件夹，只需保持你的命名空间整洁。

//SharedResource.cs===================================================
namespace SharedResources02
{
    /*
    * This is just a dummy marker class to group shared resources
    * We need it for its name and type
    * 
    * It seems the namespace needs to be the same as app root namespace
    * which needs to be the same as the assembly name.
    * I had some problems when changing the namespace, it would not work.
    * If it doesn't work for you, you can try to use full class name
    * in your DI instruction, like this one: SharedResources02.SharedResource
    * 
    * There is no magic in the name "SharedResource", you can
    * name it "MyResources" and change all references in the code
    * to "MyResources" and all will still work
    * 
    * Location seems can be any folder, although some
    * articles claim it needs to be the root project folder.
    * I do not see such problems in this example. 
    * To me, looks it can be any folder, just keep your
    * namespace tidy. 
    */

    public class SharedResource
    {
    }
}

4.2 创建包装器辅助类

我们将创建包装器辅助类/服务，并将它们通过 DI 注入到我们的代码中。

//ISharedStringLocalizer.cs=================================
namespace SharedResources02
{
    //we create this interface to use it for DI dependency setting
    public interface ISharedStringLocalizer
    {
        public LocalizedString this[string key]
        {
            get;
        }

        LocalizedString GetLocalizedString(string key);
    }
}

//SharedStringLocalizer.cs==================================================
namespace SharedResources02
{
    //we create this helper/wrapper class/service
    //that we are going to pass around in DI
    public class SharedStringLocalizer : ISharedStringLocalizer
    {
        //here is object that is doing the real work
        //it is almost the same as IStringLocalizer<SharedResource>
        private readonly IStringLocalizer localizer;

        public SharedStringLocalizer(IStringLocalizerFactory factory)
        {
            var type = typeof(SharedResource);
            var assemblyName = new AssemblyName(
                type.GetTypeInfo().Assembly.FullName ?? String.Empty);
            this.localizer = factory.Create("SharedResource", 
                assemblyName?.Name ?? String.Empty);
        }

        //in our methods, we just pass work to internal object
        public LocalizedString this[string key] => this.localizer[key];

        public LocalizedString GetLocalizedString(string key)
        {
            return this.GetLocalizedString(key);
        }
    }
}

//ISharedHtmlLocalizer.cs===============================================
namespace SharedResources02
{
    //we create this interface to use it for DI dependency setting
    public interface ISharedHtmlLocalizer
    {
        public LocalizedHtmlString this[string key]
        {
            get;
        }

        LocalizedHtmlString GetLocalizedString(string key);
    }
}

//SharedHtmlLocalizer.cs==================================================
namespace SharedResources02
{
    //we create this helper/wrapper class/service
    //that we are going to pass around in DI
    public class SharedHtmlLocalizer: ISharedHtmlLocalizer
    {
        //here is object that is doing the real work
        //it is almost the same as IHtmlLocalizer<SharedResource>
        private readonly IHtmlLocalizer localizer;

        public SharedHtmlLocalizer(IHtmlLocalizerFactory factory)
        {
            var type = typeof(SharedResource);
            var assemblyName = new AssemblyName(
                type.GetTypeInfo().Assembly.FullName ?? String.Empty);
            this.localizer = factory.Create("SharedResource", 
                assemblyName?.Name ?? String.Empty);
        }

        //in our methods, we just pass work to internal object
        public LocalizedHtmlString this[string key] => this.localizer[key];

        public LocalizedHtmlString GetLocalizedString(string key)
        {
            return this.GetLocalizedString(key);
        }
    }
}

4.3 创建语言资源文件

在 Resources 文件夹中，创建你的语言资源文件，并确保将其命名为 SharedResources.xx.resx。

4.4 配置本地化服务和中间件

本地化服务在 Program.cs 中配置

private static void AddingMultiLanguageSupportServices(WebApplicationBuilder? builder)
{
    if (builder == null) { throw new Exception("builder==null"); };

    builder.Services.AddLocalization(options => options.ResourcesPath = "Resources");
    builder.Services.AddMvc()
            .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix);
    builder.Services.Configure<RequestLocalizationOptions>(options =>
    {
        var supportedCultures = new[] { "en", "fr", "de", "it" };
        options.SetDefaultCulture(supportedCultures[0])
            .AddSupportedCultures(supportedCultures)
            .AddSupportedUICultures(supportedCultures);
    });
    builder.Services.AddSingleton<ISharedStringLocalizer, SharedStringLocalizer>();
    builder.Services.AddSingleton<ISharedHtmlLocalizer, SharedHtmlLocalizer>();
}

private static void AddingMultiLanguageSupport(WebApplication? app)
{
    app?.UseRequestLocalization();
}

4.5 选择语言/区域性

基于 [5]，本地化服务有三个默认提供程序

QueryStringRequestCultureProvider
CookieRequestCultureProvider
AcceptLanguageHeaderRequestCultureProvider

由于大多数应用程序通常会提供一种机制来使用 ASP.NET Core 区域性 cookie 来设置区域性，因此在我们的示例中，我们将只关注这种方法。

这是设置 .AspNetCore.Culture cookie 的代码

private void ChangeLanguage_SetCookie(HttpContext myContext, string? culture)
{
    if(culture == null) { throw new Exception("culture == null"); };

    //this code sets .AspNetCore.Culture cookie
    myContext.Response.Cookies.Append(
        CookieRequestCultureProvider.DefaultCookieName,
        CookieRequestCultureProvider.MakeCookieValue(new RequestCulture(culture)),
        new CookieOptions { Expires = DateTimeOffset.UtcNow.AddMonths(1) }
    );
}

可以使用 Chrome DevTools 轻松查看 Cookie

我构建了一个小型应用程序来演示它，这是我更改语言的屏幕

请注意，我在页脚添加了一些调试信息，以显示 **请求语言 Cookie** 的值，以查看应用程序是否按预期工作。

4.6 在控制器中使用本地化服务

在控制器中，当然，依赖注入 (DI) 会到来并填充所有依赖项。因此，这里将注入 SharedStringLocalizer 和 SharedHtmlLocalizer 服务。以下是代码片段

public class HomeController : Controller
{
    private readonly ILogger<HomeController> _logger;
    private readonly ISharedStringLocalizer _stringLocalizer;
    private readonly ISharedHtmlLocalizer _htmlLocalizer;

    /* Here is, of course, the Dependency Injection (DI) coming in and filling 
     * all the dependencies. 
     * So, here, services SharedStringLocalizer and SharedHtmlLocalizer
     * will be injected
     */
    public HomeController(ILogger<HomeController> logger,
        ISharedStringLocalizer stringLocalizer,
        ISharedHtmlLocalizer htmlLocalizer)
    {
        _logger = logger;
        _stringLocalizer = stringLocalizer;
        _htmlLocalizer = htmlLocalizer;
    }
    
    public IActionResult LocalizationExample(LocalizationExampleViewModel model)
{
    //so, here we use ISharedStringLocalizer
    model.IStringLocalizerInController = _stringLocalizer["Wellcome"];
    //so, here we use ISharedHtmlLocalizer
    model.IHtmlLocalizerInController = _htmlLocalizer["Wellcome"];
    return View(model);
}

4.7 在视图中使用本地化服务

在视图中，当然，依赖注入 (DI) 会到来并填充所有依赖项。因此，这里将注入 SharedStringLocalizer 和 SharedHtmlLocalizer 服务。以下是代码片段

@* LocalizationExample.cshtml ====================================================*@
@using Microsoft.AspNetCore.Mvc.Localization
@using Microsoft.Extensions.Localization

@model LocalizationExampleViewModel

@* Here is, of course, the Dependency Injection (DI) coming in and filling
 all the dependencies.
 So, here services SharedStringLocalizer and SharedHtmlLocalizer
 will be injected
*@

@inject ISharedStringLocalizer StringLocalizer
@inject ISharedHtmlLocalizer HtmlLocalizer

@{
    <div style="width:600px">
        <p class="bg-info">
            ISharedStringLocalizer Localized  in Controller:
            @Model.IStringLocalizerInController
        </p>

        <p class="bg-info">
            @{
                string? text1 = StringLocalizer["Wellcome"];
            }
            ISharedStringLocalizer Localized  in View: @text1
        </p>

        <p class="bg-info">
            ISharedHtmlLocalizer Localized  in Controller:
            @Model.IHtmlLocalizerInController
        </p>

        <p class="bg-info">
            @{
                string? text2 = "Wellcome";
            }
            ISharedHtmlLocalizer Localized  in View: @HtmlLocalizer[@text2]
        </p>
    </div>
}

4.8 执行结果

执行结果如下所示