ASP.NET Core WebAPI實現本地化（單資源文件）

在Startup ConfigureServices 註冊本地化所需要的服務AddLocalization和 Configure<RequestLocalizationOptions>

      public void ConfigureServices(IServiceCollection services)
        {
            services.AddLocalization();
            services.Configure<RequestLocalizationOptions>(options =>
            {
                var supportedCultures = new List<CultureInfo>
                {
                    new CultureInfo("en-us"),
                    new CultureInfo("zh-cn")
                };

                options.DefaultRequestCulture = new RequestCulture(culture: "en-us", uiCulture: "en-us");
                options.SupportedCultures = supportedCultures;
                options.SupportedUICultures = supportedCultures;
                options.RequestCultureProviders = new IRequestCultureProvider[] { new RouteDataRequestCultureProvider { IndexOfCulture = 1, IndexofUiCulture = 1 } };
            });
            services.Configure<RouteOptions>(options =>
            {
                options.ConstraintMap.Add("culture", typeof(LanguageRouteConstraint));
            });
            services.AddControllers();
        }

在Startup.cs類的Configure 方法中添加請求本地化中間件。

    var localizeOptions = app.ApplicationServices.GetService<IOptions<RequestLocalizationOptions>>();
            app.UseRequestLocalization(localizeOptions.Value);

RequestCultureProvider 它使用簡單的委托來確定當前的本地化區域性，當然我們還可以通過RequestCultureProvider自定義源的請求區域信息比如說配置文件或者資料庫都是可以的.或者說我們可以選用預設的一些方式讓我們去獲取到當前區域.

ASP.NET Core 本地化預設向我們提供了四個方式，可用於確定正在執行的請求的當前區域性：

• QueryStringRequestCultureProvider
• CookieRequestCultureProvider
• AcceptLanguageHeaderRequestCultureProvider
• CustomRequestCultureProvider

如下所示我將通過路由的方式,去確定當前區域

   public class RouteDataRequestCultureProvider : RequestCultureProvider
    {
        public int IndexOfCulture;
        public int IndexofUiCulture;

        public override Task<ProviderCultureResult> DetermineProviderCultureResult(HttpContext httpContext)
        {
            if (httpContext == null)
                throw new ArgumentNullException(nameof(httpContext));
            string uiCulture;

            string culture = uiCulture = httpContext.Request.Path.Value.Split('/')[IndexOfCulture];

            var providerResultCulture = new ProviderCultureResult(culture, uiCulture);

            return Task.FromResult(providerResultCulture);
        }
    }

通過如下代碼片段實現IRouteConstraint對路由做相應的約束

    public class LanguageRouteConstraint : IRouteConstraint
    {
        public bool Match(HttpContext httpContext, IRouter route, string routeKey, RouteValueDictionary values, RouteDirection routeDirection)
        {

            if (!values.ContainsKey("culture"))
                return false;

            var culture = values["culture"].ToString();
            return culture == "en-us" || culture == "zh-cn";
        }
    }

添加區域資源文件

註入IStringLocalizer<T>，StringLocalizer將通過傳遞的共用資源(T)的值映射到資源文件,然後將本地化根據字元串的名稱從資源文件返迴響應的值

    [Route("{culture:culture}/[controller]")]
    [ApiController]
    public class HomeController : ControllerBase
    {
        private readonly IStringLocalizer<Resource> localizer;
        public HomeController(IStringLocalizer<Resource> localizer)
        {
            this.localizer = localizer;
        }
        public string Get()
        {
            return localizer["Home"];
        }
    }

如下圖所示

Reference

https://github.com/hueifeng/BlogSample/tree/master/src/LocalizationSingleResx