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。
代码如下:

<configuration> 
<system.web> 
<globalization resourceProviderFactoryType="Westwind.Globalization.DbSimpleResourceProviderFactory,Westwind.Globalization" /> 
</system.web> 
</configuration> 
 

建立自定义资源提供者类: 
1.工厂类 
 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 
 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 
 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() 
{ 
} 
} 
 
完毕。 
本人没有测试过,待测试通过,献上最精炼的源代码.敬请稍候.