枚舉的多語言顯示

關于枚舉類型的多語言顯示，其實就是Globalization的問題。解決方案當然不止一種，這里介紹一種可用性和擴展性的比較好的通用方法。   顯然這里自己去實現自定義格式化，即通過IFo...

關于枚舉類型的多語言顯示，其實就是Globalization的問題。解決方案當然不止一種，這里介紹一種可用性和擴展性的比較好的通用方法。

 

顯然這里自己去實現自定義格式化，即通過IFormatable、IFormatProvider、ICustomFormatter等接口已達到Globalization有點小題大作了，而另外一個很容易想到的點是通過DiaplayMember實現顯示值得自定義（對于簡單Binding，例如ComboBox、ListBox等只用重載ToString就可以了）。

 

首先，我們希望Binding整個枚舉類型的每一個值，也就是說，我們需要把這個枚舉的所有值變成一個數據源，為了實現這一點，我們可以使用Enum上的helper方法Enum.GetValues(Type)來返回一個對所有值得枚舉，然后依次添加到IList對象或者IListSource接口即可。

 

if (!typeof(EnumType).IsEnum)
{
    throw new NotSupportedException("Can not support type: " + typeof(EnumType).FullName);
    // It's better use resource version as below.
    // throw new NotSupportedException(SR.GetString("TYPE_NOT_SUPPORT",  typeof(EnumType).FullName));
}

// Use Enum helper enumerator list all enum values and add to current context.
foreach (EnumType value in Enum.GetValues(typeof(EnumType)))
{
    //TODO: add each value to IList
    base.Add(new EnumAdapter(value));
}

 

然后，取到了值，由于我們希望自定義Binding顯示，那么需要對枚舉值進行封裝，而在這個封裝里面，我們可以實現多語言的支持。

 

/// <summary>
///   Enum value adapter, used to get values from each Cultures.
/// </summary>
public sealed class EnumAdapter
{
    /**//// <summary>
    ///   Storage the actual Enum value.
    /// </summary>
    private EnumType _value;

    /**//// <summary>
    ///   Constructor an <see cref="EnumAdapter"/>.
    /// </summary>
    /// <param name="value">The enum value.</param>
    /// <exception cref="">
    ///   
    /// </exception>
    public EnumAdapter(EnumType value)
    {
        if (!Enum.IsDefined(typeof(EnumType), value))
        {
            throw new ArgumentException(string.Format("{0} is not defined in {1}", value, typeof(EnumType).Name), "value");
            // It's better use resource version as below.
            // throw new ArgumentException(SR.GetString("ENUM_NOT_DEFINED_FMT_KEY", value, typeof(EnumType).Name), "value");
        }
        _value = value;
    }

    /**//// <summary>
    ///   Gets the actual enum value.
    /// </summary>
    public EnumType Value
    {
        get { return _value; }
    }

    /**//// <summary>
    ///   Gets the display value for enum value by search local resource with currrent UI lture 
    ///   and special key which is concated from Enum type name and Enum value name.
    /// </summary>
    /// <remarks>
    ///   This would get correct display value by accessing location resource with current UI Culture.
    /// </remarks>
    public string DisplayValue
    {
        get { return SR.GetString(string.Format("{0}.{1}", typeof(EnumType).Name, _value.ToString())); }
    }

    //TODO: If you want more, please add below
}

 

至此，整個功能的框架已經完成，下面我們來看看一些細節——如何對資源讀取和管理的封裝：

 

/// <summary>
///   Constructor a new <see cref="SR"/>.
/// </summary>
internal SR()
{
    //TODO: If you modified resource location, please update here
    this.resources = new System.Resources.ResourceManager(
        string.Concat(typeof(EnumAdapter).Namespace, ".Resource"), 
        base.GetType().Assembly);
}

/**//// <summary>
///   Get singleton instance.
/// </summary>
/// <returns>A singleton <see cref="SR"/></returns>
private static SR GetLoader()
{
    if (loader == null)
    {
        lock (SR.InternalSyncObject)
        {
            if (loader == null)
            {
                loader = new SR();
            }
        }
    }
    return loader;
}

/**//// <summary>
///   Gets an object from resources by special key, which provided by <paramref name="name"/>.
/// </summary>
/// <param name="name">Resource accessed key</param>
/// <returns>return stored object in resource. if resource not found, return <paramref name="name"/> as object.</returns>
public static object GetObject(string name)
{
    SR loader = GetLoader();
    if (loader == null)
    {
        return null;
    }
    try
    {
        return loader.resources.GetObject(name, Culture);
    }
    catch { }
    return name;
}

/**//// <summary>
///   Gets a string from resources by special key, which provided by <paramref name="name"/>.
/// </summary>
/// <param name="name">Resource accessed key</param>
/// <returns>return stored string in resource. If resource not found, retuen <paramref name="name"/> as result.</returns>
public static string GetString(string name)
{
    SR loader = GetLoader();
    if (loader == null)
    {
        return null;
    }
    try
    {
        return loader.resources.GetString(name, Culture);
    }
    catch { }
    return name;
}

/**//// <summary>
///   Gets a formatted string from resources by special key, which provided by <paramref name="name"/> and optional parameters.
/// </summary>
/// <param name="name">Resource accessed key</param>
/// <param name="args">format arguments.</param>
/// <returns>return stored string in resource. If resource not found, use <paramref name="name"/> as formator, return the formatted string.</retur
public static string GetString(string name, params object[] args)
{
    SR loader = GetLoader();
    if (loader == null)
    {
        return null;
    }
    string format = name;
    try
    {
        format = loader.resources.GetString(name, Culture);
    }
    catch { }

    if ((args == null) || (args.Length <= 0))
    {
        return format;
    }

    // It's better cut long arg for formating.
    for (int i = 0; i < args.Length; i++)
    {
        string arg = args[i] as string;
        if ((arg != null) && (arg.Length > 0x400))
        {
            args[i] = arg.Substring(0, 0x3fd) + "";
        }
    }
    return string.Format(System.Globalization.CultureInfo.CurrentCulture, format, args);
}

 

OK，大功告成，有了這么一個封裝，在應用里就可以簡單的這么幾句夠搞定。

 

private void Form1_Load(object sender, EventArgs e)
{
    this.comboBox1.DataSource = new EnumDataSource<Sex>();
    this.comboBox1.DisplayMember = "DisplayValue";
    this.comboBox1.ValueMember = "Value";
}

public enum Sex
{
    Male,
    Female
}