建立自定义的数据驱动的本地化资源provider

原文很长,为了便于阅读和理解,特将该文章改写成通俗易懂而且内容精炼的中文.

预备知识:系统默认的处理资源和本地化的方法是使用resx文件存储资源.

要使用自定义的resource provider,需要2个步骤:
a) 修改web.config 文件,以便系统使用自定义的资源提供者
b) 建立自定义资源提供者类,最少包括3个:
1.ResourceProviderFactory,工厂类,用来建立ResourceProvider对象.
2.ResourceProvider,实现IResourceProvider,IImplicitResourceProvider,IwwResourceProvider 接口.
3.ResourceReader 实现IResourceReader.

修改web.config 文件,以使用自定义的资源提供者。

复制代码代码如下:

建立自定义资源提供者类:
1.工厂类

复制代码代码如下:

[DesignTimeResourceProviderFactoryAttribute(typeof(DbDesignTimeResourceProviderFactory))]
public class DbSimpleResourceProviderFactory : ResourceProviderFactory
{

public override IResourceProvider CreateGlobalResourceProvider(string classname)
{
return new DbSimpleResourceProvider(null, classname);
}

public override IResourceProvider CreateLocalResourceProvider(string virtualPath)
{

string ResourceSetName = DbResourceConfiguration.Current.StripVirtualPath(virtualPath);
return new DbSimpleResourceProvider(null,ResourceSetName.ToLower());
}
}

2.提供者类

复制代码代码如下:

public class DbSimpleResourceProvider : IResourceProvider, IImplicitResourceProvider
{

private string _ResourceSetName;

private IDictionary _resourceCache;

private DbSimpleResourceProvider()
{ }

public DbSimpleResourceProvider(string virtualPath, string className)
{
_ResourceSetName = className;
}

private IDictionary GetResourceCache(string cultureName)
{
if (cultureName == null)
cultureName = "";

if (this._resourceCache == null)
this._resourceCache = new ListDictionary();

IDictionary Resources = this._resourceCache[cultureName] as IDictionary;
if (Resources == null)
{
// *** DEPENDENCY HERE (#1): Using DbResourceDataManager to retrieve resources

// *** Use datamanager to retrieve the resource keys from the database
DbResourceDataManager Data = new DbResourceDataManager();
Resources = Data.GetResourceSet(cultureName as string, this._ResourceSetName);
this._resourceCache[cultureName] = Resources;
}

return Resources;
}

public void ClearResourceCache()
{
this._resourceCache.Clear();
}

object IResourceProvider.GetObject(string ResourceKey, CultureInfo Culture)
{
string CultureName = null;
if (Culture != null)
CultureName = Culture.Name;
else
CultureName = CultureInfo.CurrentUICulture.Name;

return this.GetObjectInternal(ResourceKey, CultureName);
}

object GetObjectInternal(string ResourceKey, string CultureName)
{
IDictionary Resources = this.GetResourceCache(CultureName);

object value = null;
if (Resources == null)
value = null;
else
value = Resources[ResourceKey];

// *** If we're at a specific culture (en-Us) and there's no value fall back
// *** to the generic culture (en)
if (value == null && CultureName.Length > 3)
{
// *** try again with the 2 letter locale
return GetObjectInternal(ResourceKey,CultureName.Substring(0,2) );
}

// *** If the value is still null get the invariant value
if (value == null)
{
Resources = this.GetResourceCache("");
if (Resources == null)
value = null;
else
value = Resources[ResourceKey];
}

// *** If the value is still null and we're at the invariant culture
// *** let's add a marker that the value is missing
// *** this also allows the pre-compiler to work and never return null
if (value == null && string.IsNullOrEmpty(CultureName))
{
// *** No entry there
value = "";

// *** DEPENDENCY HERE (#2): using DbResourceConfiguration and DbResourceDataManager to optionally
// add missing resource keys

// *** Add a key in the repository at least for the Invariant culture
// *** Something's referencing but nothing's there
if (DbResourceConfiguration.Current.AddMissingResources)
new DbResourceDataManager().AddResource(ResourceKey, value.ToString(), "", this._ResourceSetName);

}

return value;
}

3.Reader类

复制代码代码如下:

public class DbSimpleResourceReader : IResourceReader
{
private IDictionary _resources;

public DbSimpleResourceReader(IDictionary resources)
{
_resources = resources;
}
IDictionaryEnumerator IResourceReader.GetEnumerator()
{
return _resources.GetEnumerator();
}
void IResourceReader.Close()
{
}
IEnumerator IEnumerable.GetEnumerator()
{
return _resources.GetEnumerator();
}
void IDisposable.Dispose()
{
}
}