Blazor hosted Webassembly项目如何基于数据库资源实现本地化

实现方案 #

Blazor WASM 客户端无法直接访问服务端数据库，你需要通过「服务端暴露本地化接口 + 客户端自定义 IStringLocalizer 实现」的方式完成配置，具体步骤如下：

1. 服务端改造 #

你已经完成了数据库本地化的基础配置，只需要新增一个接口提供翻译资源即可：

• 新增 LocalizationController 控制器，注入你已实现的数据库本地化服务/业务DbContext，提供查询接口：

[ApiController]
[Route("api/[controller]")]
public class LocalizationController : ControllerBase
{
    // 你之前教程实现的数据库本地化读取服务
    private readonly IDbLocalizationService _localizationService;

    public LocalizationController(IDbLocalizationService localizationService)
    {
        _localizationService = localizationService;
    }

    [HttpGet]
    public ActionResult<Dictionary<string, string>> GetAll([FromQuery] string culture, [FromQuery] string resourceType = null)
    {
        var resources = _localizationService.GetResources(culture, resourceType);
        return Ok(resources.ToDictionary(x => x.Key, x => x.Value));
    }
}

2. 客户端实现自定义本地化服务 #

替换默认的resx实现，自定义IStringLocalizer和对应工厂，调用服务端接口拉取翻译：

• 先实现自定义字符串定位器：

public class ApiStringLocalizer : IStringLocalizer
{
    private readonly HttpClient _httpClient;
    private readonly string _resourceType;
    private Dictionary<string, string> _localizations = new();

    public ApiStringLocalizer(HttpClient httpClient, string resourceType)
    {
        _httpClient = httpClient;
        _resourceType = resourceType;
    }

    public LocalizedString this[string name]
    {
        get
        {
            if (_localizations.TryGetValue(name, out var value))
            {
                return new LocalizedString(name, value);
            }
            // 未命中时返回键本身，和默认行为一致
            return new LocalizedString(name, name, resourceNotFound: true);
        }
    }

    public LocalizedString this[string name, params object[] arguments]
    {
        get
        {
            var format = this[name];
            return new LocalizedString(name, string.Format(format.Value, arguments), format.ResourceNotFound);
        }
    }

    // 初始化时拉取对应语言的所有翻译缓存到本地
    public async Task LoadResourcesAsync(CultureInfo culture)
    {
        var response = await _httpClient.GetFromJsonAsync<Dictionary<string, string>>(
            $"api/localization?culture={culture.Name}&resourceType={_resourceType}");
        _localizations = response ?? new Dictionary<string, string>();
    }

    // 其余IStringLocalizer接口方法按需求实现即可
    public IEnumerable<LocalizedString> GetAllStrings(bool includeParentCultures)
    {
        return _localizations.Select(kv => new LocalizedString(kv.Key, kv.Value));
    }
}

• 再实现对应的工厂类，用来生成带泛型参数的IStringLocalizer<T>实例：

public class ApiStringLocalizerFactory : IStringLocalizerFactory
{
    private readonly HttpClient _httpClient;

    public ApiStringLocalizerFactory(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public IStringLocalizer Create(Type resourceSource)
    {
        var localizer = new ApiStringLocalizer(_httpClient, resourceSource.FullName);
        // 初始化时加载当前语言资源
        localizer.LoadResourcesAsync(CultureInfo.CurrentCulture).Wait();
        return localizer;
    }

    public IStringLocalizer Create(string baseName, string location)
    {
        var localizer = new ApiStringLocalizer(_httpClient, baseName);
        localizer.LoadResourcesAsync(CultureInfo.CurrentCulture).Wait();
        return localizer;
    }
}

3. 客户端服务注册替换 #

在客户端项目的Program.cs中替换默认的本地化服务实现：

var builder = WebAssemblyHostBuilder.CreateDefault(args);
// 配置指向服务端的HttpClient
builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
// 替换默认的本地化工厂实现
builder.Services.AddSingleton<IStringLocalizerFactory, ApiStringLocalizerFactory>();
builder.Services.AddScoped(typeof(IStringLocalizer<>), typeof(StringLocalizer<>));
// 配置支持的语言
builder.Services.Configure<RequestLocalizationOptions>(options =>
{
    var supportedCultures = new[]
    {
        new CultureInfo("en"),
        new CultureInfo("zh-CN")
    };
    options.DefaultRequestCulture = new RequestCulture("zh-CN");
    options.SupportedCultures = supportedCultures;
    options.SupportedUICultures = supportedCultures;
});

await builder.Build().RunAsync();

注意事项 #

• 可以将拉取到的本地化资源缓存到localStorage中，切换语言时清空缓存重新拉取，减少重复请求
• 如果不需要按资源类型拆分翻译，接口可以去掉resourceType参数，统一返回所有翻译即可
• 首次加载时可以提前拉取一次资源，避免页面显示延迟

内容的提问来源于stack exchange，提问作者T0bi