> 說明

對於Asp.net Core MVC架構的Web程式，可使用MVC自身提供的國際化方法，實現對控制器、檢視、資料註釋內容的國際化處理。

> 實現

1、在Startup.cs中新增國際化服務

* 在ConfigureServices中新增配置，指定資原始檔夾名稱，新增支援的多語言文化，指定預設的語言

```C#
public void ConfigureServices(IServiceCollection services)
{
	#region 多語言支援
	services.AddLocalization(options => options.ResourcesPath = "Resources");

services.AddMvc()
		.AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix)
		.AddDataAnnotationsLocalization();

services.Configure<requestlocalizationoptions>(options =>
	{
		var supportedCultures = new List<cultureinfo>
		{
			new CultureInfo("zh-CN"),
			new CultureInfo("en-US"),
		};

options.DefaultRequestCulture = new RequestCulture("zh-CN");
		options.SupportedCultures = supportedCultures;
		options.SupportedUICultures = supportedCultures;
	});
	#endregion

services.AddControllersWithViews();
}
```

* 在Configure中新增多語言配置

```c#
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
	#region 多語言支援
	IList<cultureinfo> supportedCultures = new List<cultureinfo>
	{
		new CultureInfo("en-US"),
		new CultureInfo("zh-CN"),
	};
	app.UseRequestLocalization(new RequestLocalizationOptions
	{
		DefaultRequestCulture = new RequestCulture("zh-CN"),
		SupportedCultures = supportedCultures,
		SupportedUICultures = supportedCultures
	});
	#endregion
	
	......
```

2、新增多語言切換方法和檢視頁面

* 在HomeController.cs中新增多語言切換方法

```c#
[HttpPost]
public IActionResult SetLanguage(string culture, string returnUrl)
{
	Response.Cookies.Append(
		CookieRequestCultureProvider.DefaultCookieName,
		CookieRequestCultureProvider.MakeCookieValue(new RequestCulture(culture)),
		new CookieOptions { Expires = DateTimeOffset.UtcNow.AddYears(1) }
	);

return LocalRedirect(returnUrl);
}
```

* 在Views=>Shared中新增用於多語言切換操作的分部檢視

_SelectLanguagePartial.cshtml

```html
@using Microsoft.AspNetCore.Builder
@using Microsoft.AspNetCore.Http.Features
@using Microsoft.AspNetCore.Localization
@using Microsoft.AspNetCore.Mvc.Localization
@using Microsoft.Extensions.Options

@inject IViewLocalizer Localizer
@inject IOptions<requestlocalizationoptions> LocOptions

@{
    var requestCulture = Context.Features.Get<irequestculturefeature>();
    var cultureItems = LocOptions.Value.SupportedUICultures
    .Select(c => new SelectListItem { Value = c.Name, Text = c.DisplayName })
    .ToList();
    var returnUrl = string.IsNullOrEmpty(Context.Request.Path) ? "~/" : $"~{Context.Request.Path.Value}";
}

<div title="@Localizer[" request="" culture="" provider:="">
    <form id="selectLanguage" asp-controller="Home" asp-action="SetLanguage" asp-route-returnurl="@returnUrl" method="post" class="form-horizontal" role="form">
        <label asp-for="@requestCulture.RequestCulture.UICulture.Name">@Localizer["Language:"]</label>
        <select name="culture" onchange="this.form.submit();" asp-for="@requestCulture.RequestCulture.UICulture.Name" asp-items="cultureItems">
        </select>
    </form>
</div>
```

將此檢視新增到_Layout.cshtml中，例如新增到腳註欄

```html
<footer class="border-top footer text-muted">
	<div class="row">
		<div class="col-md-6">
			© @System.DateTime.Now.Year - WebApplication1 - <a asp-area="" asp-controller="Home" asp-action="Privacy" rel="nofollow">Privacy</a>
		</div>
		<div class="col-md-6" text-right="">
			@await Html.PartialAsync("_SelectLanguagePartial")
		</div>
	</div>
</footer>
```

3、新增多語言資原始檔

* 在專案根路徑下新增資原始檔夾，名稱與Startup.cs中配置的名稱相同，這裡為Resources資料夾

在Resources下建立Controllers和Views兩個子資料夾，Views子資料夾裡的路徑與檢視資料夾Views的路徑對應，建立簡體中文zh-CN和美國英語en-US的resx資原始檔。例如以下幾個資源路徑

Resources=>Controllers=>HomeController.zh-CN.resx

Resources=>Controllers=>HomeController.en-US.resx

Resources=>Views=>Shared=>Layout.zh-CN.resx

Resources=>Views=>Shared=>Layout.en-US.resx

Resources=>Views=>Home=>Index.zh-CN.resx

Resources=>Views=>Home=>Index.en-US.resx

Resources=>Views=>Home=>Privacy.zh-CN.resx

Resources=>Views=>Home=>Privacy.en-US.resx

4、控制器內容的國際化

在控制器中，透過引入`IStringLocalizer`介面實現。`IStringLocalizer` 不要求在資原始檔中儲存預設語言字串，開發針對本地化應用時無需在開發初期建立資原始檔。 下面的程式碼演示如何針對本地化包裝字串“Hello!”，收集這些需要本地化的詞條，新增到多語言資原始檔中。

```c#
public class HomeController : Controller
{
	// 控制器程式碼的國際化支援
	private readonly IStringLocalizer<homecontroller> _localizer;

public HomeController(IStringLocalizer<homecontroller> localizer)
	{
		_localizer = localizer;
	}
	
	...
	
    // 一個演示方法
    public IActionResult Hello()
    {
    return Content(_localizer["Hello!"]);
    }
}
```

頁面位址列鍵入如下URL: https://localhost:44392/Home/Hello，顯示內容將根據選擇的語言自動切換。也可以在URL中附加文化引數，來觀察顯示語言的變化，如

https://localhost:44392/Home/Hello?culture=zh-CN 將切換為中文顯示，

https://localhost:44392/Home/Hello?culture=en-US 將切換為英文顯示。

5、檢視頁面內容的國際化

在檢視中，透過引入`IViewLocalizer`介面實現。`IViewLocalizer`同樣不要求在資原始檔中儲存預設語言字串，開發針對本地化應用時無需在開發初期建立資原始檔。收集這些需要本地化的詞條，新增到多語言資原始檔中。

```c#
@using Microsoft.AspNetCore.Mvc.Localization

@inject IViewLocalizer Localizer

@{
    ViewData["Title"] = Localizer["Home Page"];
}

<div class="text-center">
    <h1 class="display-4">@Localizer["Welcome"]</h1>
    <p>@Localizer["Learn about"] <a href="https://docs.microsoft.com/aspnet/core" rel="nofollow">@Localizer["building Web apps with ASP.NET Core"]</a>.</p>
</div>
```

6、DataAnnotations（資料註釋）的國際化

DataAnnotations 錯誤訊息已使用 `IStringLocalizer<t>` 本地化。 直接收集這些需要本地化的詞條，新增到多語言資原始檔中。

```C#
public class RegisterViewModel
{
    [Required(ErrorMessage = "The Email field is required.")]
    [EmailAddress(ErrorMessage = "The Email field is not a valid email address.")]
    [Display(Name = "Email")]
    public string Email { get; set; }

[Required(ErrorMessage = "The Password field is required.")]
    [StringLength(8, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 6)]
    [DataType(DataType.Password)]
    [Display(Name = "Password")]
    public string Password { get; set; }

[DataType(DataType.Password)]
    [Display(Name = "Confirm password")]
    [Compare("Password", ErrorMessage = "The password and confirmation password do not match.")]
    public string ConfirmPassword { get; set; }
}
```

![資原始檔目錄結構](http://img.blog.itpub.net/blog/2021/09/26/a7db71db2621e7e1.png?x-oss-process=style/bb "資原始檔目錄結構")

![中文頁面](http://img.blog.itpub.net/blog/2021/09/26/47e9889f7ff0f393.png?x-oss-process=style/bb "中文頁面")

![英文頁面](http://img.blog.itpub.net/blog/2021/09/26/ff148df5632a7133.png?x-oss-process=style/bb "英文頁面")</t></homecontroller></homecontroller></irequestculturefeature></requestlocalizationoptions></cultureinfo></cultureinfo></cultureinfo></requestlocalizationoptions>

Asp.net Core MVC 程式的國際化處理

相關文章