从零到多页复用：我的WPF MVVM国际化实践

第一步：基础实现，资源文件入门

我的项目是一个基于WPF和MVVM的配置工具，界面上有“Save”和“Refresh”两个按钮，需要支持英文和中文切换。WPF的国际化通常从资源文件（.resx）入手，于是我先尝试了最简单的方法。

在项目中，我创建了一个Resources文件夹，添加了两个资源文件：

• Resources.resx（默认英文）：
  • save: Save
  • refresh: Refresh
• Resources.zh-CN.resx（中文）：
  • save: 保存
  • refresh: 刷新

在XAML中，我尝试直接绑定到资源：

<Button Content="{Binding Source={x:Static local:Resources.save}}" />

但很快发现，这种方式在运行时切换语言时不会更新UI，因为静态绑定无法响应动态变化。于是，我转向代码隐藏文件，在UserControl中定义属性：

public partial class PageTemplate : UserControl
{
    public string Save => Resources.ResourceManager.GetString("save");
    public string Refresh => Resources.ResourceManager.GetString("refresh");

    public PageTemplate()
    {
        InitializeComponent();
        DataContext = this;
    }
}

XAML改为：

<Button Content="{Binding Save}" />

这时候，按钮显示了英文，但点击“中文”按钮后，文本没变。我意识到，语言切换需要更新CultureInfo，于是引入了一个单例类LanguageManager：

public class LanguageManager
{
    private static readonly Lazy<LanguageManager> _instance = new Lazy<LanguageManager>(() => new LanguageManager());
    public static LanguageManager Instance => _instance.Value;

    private CultureInfo _currentCulture = new CultureInfo("en-US");

    public CultureInfo CurrentCulture
    {
        get => _currentCulture;
        set
        {
            _currentCulture = value;
            Thread.CurrentThread.CurrentUICulture = value;
        }
    }

    public string GetString(string key) => Resources.ResourceManager.GetString(key, _currentCulture) ?? $"[{key}]";
}

在PageTemplate中使用：

private readonly LanguageManager _languageManager = LanguageManager.Instance;
public string Save => _languageManager.GetString("save");

加上切换命令：

<Button CommandParameter="zh-CN" Command="{Binding SwitchLanguageCommand}" Content="中文" />

public ICommand SwitchLanguageCommand => new RelayCommand<string>(lang =>
{
    _languageManager.CurrentCulture = new CultureInfo(lang);
});

然而，切换后UI还是没更新。我调试发现，虽然CultureInfo变了，但绑定没有刷新。加上INotifyPropertyChanged后问题解决：

public partial class PageTemplate : UserControl, INotifyPropertyChanged
{
    private readonly LanguageManager _languageManager = LanguageManager.Instance;
    public string Save => _languageManager.GetString("save");

    public PageTemplate()
    {
        InitializeComponent();
        DataContext = this;
        _languageManager.PropertyChanged += (s, e) => OnPropertyChanged(null);
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

终于，切换语言时按钮文本正常更新了！

第二步：依赖属性，提升WPF体验

虽然基础功能实现了，但这种只读属性方式让我觉得不够“WPF”。在WPF中，依赖属性更适合绑定场景。于是我改用依赖属性：

public static readonly DependencyProperty SaveProperty = DependencyProperty.Register(
    nameof(Save), typeof(string), typeof(PageTemplate), new PropertyMetadata(string.Empty));

public string Save
{
    get => (string)GetValue(SaveProperty);
    set => SetValue(SaveProperty, value);
}

public PageTemplate()
{
    InitializeComponent();
    DataContext = this;
    UpdateLocalizedStrings();
    _languageManager.PropertyChanged += (s, e) => UpdateLocalizedStrings();
}

private void UpdateLocalizedStrings()
{
    Save = _languageManager.GetString("save");
    Refresh = _languageManager.GetString("refresh");
}

这样，绑定更符合WPF的习惯，而且UI更新更可靠。下一步，我把语言切换按钮改成了下拉框：

<ComboBox ItemsSource="{Binding Languages}"
          DisplayMemberPath="DisplayName"
          SelectedValuePath="CultureName"
          SelectedValue="{Binding SelectedLanguage, Mode=TwoWay}"/>

public List<LanguageOption> Languages { get; } = new List<LanguageOption>
{
    new LanguageOption("English", "en-US"),
    new LanguageOption("中文", "zh-CN")
};

public static readonly DependencyProperty SelectedLanguageProperty = DependencyProperty.Register(
    nameof(SelectedLanguage), typeof(string), typeof(PageTemplate),
    new PropertyMetadata("en-US", OnSelectedLanguageChanged));

public string SelectedLanguage
{
    get => (string)GetValue(SelectedLanguageProperty);
    set => SetValue(SelectedLanguageProperty, value);
}

private static void OnSelectedLanguageChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    var page = (PageTemplate)d;
    page._languageManager.CurrentCulture = new CultureInfo((string)e.NewValue);
}

这让界面更友好，用户体验也提升了。

第三步：多页面复用，减少重复代码

项目发展到有多个页面时，我发现每个页面都重复定义Save、Refresh和语言切换逻辑，太繁琐了。我决定把国际化集中化，先创建了一个基类：

public class BaseViewModel : INotifyPropertyChanged
{
    protected readonly LanguageService _languageService = LanguageService.Instance;

    public string Save => _languageService.GetString("save");
    public string Refresh => _languageService.GetString("refresh");

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

LanguageService接管了语言管理：

public class LanguageService : INotifyPropertyChanged
{
    private static readonly Lazy<LanguageService> _instance = new Lazy<LanguageService>(() => new LanguageService());
    public static LanguageService Instance => _instance.Value;

    private CultureInfo _currentCulture = new CultureInfo("en-US");
    public CultureInfo CurrentCulture
    {
        get => _currentCulture;
        set
        {
            _currentCulture = value;
            Thread.CurrentThread.CurrentUICulture = value;
            OnPropertyChanged(null);
        }
    }

    public string GetString(string key) => Resources.ResourceManager.GetString(key, _currentCulture) ?? $"[{key}]";

    public List<LanguageOption> Languages { get; } = new List<LanguageOption>
    {
        new LanguageOption("English", "en-US"),
        new LanguageOption("中文", "zh-CN")
    };

    public string SelectedLanguage
    {
        get => _currentCulture.Name;
        set => CurrentCulture = new CultureInfo(value);
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

页面只需继承BaseViewModel：

public class PageTemplateViewModel : BaseViewModel { }
public partial class PageTemplate : UserControl
{
    public PageTemplate()
    {
        InitializeComponent();
        DataContext = new PageTemplateViewModel();
    }
}

XAML绑定到全局服务：

<ComboBox ItemsSource="{Binding Languages, Source={x:Static services:LanguageService.Instance}}"
          SelectedValue="{Binding SelectedLanguage, Source={x:Static services:LanguageService.Instance}, Mode=TwoWay}"/>

第四步：动态化，应对更多字符串

页面越来越多，字符串也从save、refresh扩展到title、user等十几个。我不想在BaseViewModel中为每个字符串写属性，于是尝试了动态方案：

public class BaseViewModel : INotifyPropertyChanged
{
    protected readonly LanguageService _languageService = LanguageService.Instance;

    public dynamic Strings => new LocalizedStrings(_languageService);

    public BaseViewModel()
    {
        _languageService.PropertyChanged += (s, e) => OnPropertyChanged(nameof(Strings));
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}

public class LocalizedStrings : DynamicObject
{
    private readonly LanguageService _languageService;

    public LocalizedStrings(LanguageService languageService)
    {
        _languageService = languageService;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        result = _languageService.GetString(binder.Name.ToLower());
        return true;
    }
}

XAML改为：

<Button Content="{Binding Strings.save}" />
<TextBlock Text="{Binding Strings.title}" />

现在，无论有多少字符串，我只需在资源文件里添加键值对，代码完全不用改动。这种方式让我从繁琐的属性定义中解放出来。

总结与反思

从最初的简单资源文件，到依赖属性，再到多页面复用，最后用动态对象优化，我的国际化之旅走了不少弯路，但每一步都让我更理解WPF和MVVM的精髓：

• 起步简单：资源文件和基本绑定能快速实现单页面国际化。
• 提升体验：依赖属性和下拉框让切换更自然。
• 复用为王：集中化管理避免重复劳动。
• 动态扩展：用动态对象应对未来需求。

如果你的项目也有国际化需求，不妨从基础开始，根据规模逐步优化。你遇到过哪些国际化难题？欢迎留言分享！