Creating Multilingual Websites - Part 3

using System;
using System.Collections;
using System.Collections.Specialized;
using System.IO;
using System.Web;
using System.Web.Caching;
using System.Xml;

namespace Localization
{
  /// <summary>
  /// The ResourceManagerXml is an implementation of the ResourceManager driven by XML files
  /// </summary>
  public class ResourceManagerXml : ResourceManager
  {
    #region Fields and Properties
    private string fileName;
    #endregion


    #region Constructors
    public ResourceManagerXml(NameValueCollection parameters)
    {
      if (parameters == null || parameters["languageFilePath"] == null)
      {
        throw new ApplicationException("ResourceManagerXml requires fileName attribute in configuraiton.");
      }
      fileName = parameters["languageFilePath"];
    }
    #endregion


    #region Provider API
    /// <remarks>
    ///   When in DEBUG mode, an ApplicationException will be thrown if the key isn't found
    /// </remarks>
    protected override string RetrieveString(string key)
    {
      NameValueCollection messages = GetResources();
      if (messages[key] == null)
      {
        messages[key] = string.Empty;
#if DEBUG
        throw new ApplicationException("Resource value not found for key: " + key);
#endif
      }
      return messages[key];
    }
    protected override LocalizedImageData RetrieveImage(string key)
    {
      Hashtable imageData = GetImages();
      if (imageData[key] == null)
      {
        imageData[key] = new LocalizedImageData(0, 0, string.Empty);
#if DEBUG
        throw new ApplicationException("Resource value not found for key: " + key);
#endif            
      }
      return (LocalizedImageData)imageData[key];
    }
    #endregion


    #region Private Methods
    private NameValueCollection GetResources()
    {
      string currentCulture = ResourceManager.CurrentCultureName;
      string defaultCulture = LocalizationConfiguration.GetConfig().DefaultCultureName;
      string cacheKey = "Localization:" + defaultCulture + ':' + currentCulture;
      if (HttpRuntime.Cache[cacheKey] == null)
      {
        NameValueCollection resource = new NameValueCollection();
        LoadResources(resource, defaultCulture, cacheKey);
        if (defaultCulture != currentCulture)
        {
          try
          {
            LoadResources(resource, currentCulture, cacheKey);
          }
          catch (FileNotFoundException)
          {}
        }
      }
      return (NameValueCollection)HttpRuntime.Cache[cacheKey];
    }
    private void LoadResources(NameValueCollection resource, string culture, string cacheKey)
    {
      string file = string.Format("{0}\\{1}\\Resource.xml", fileName, culture);
      XmlDocument xml = new XmlDocument();
      xml.Load(file);
      foreach (XmlNode n in xml.SelectSingleNode("Resource"))
      {
        if (n.NodeType != XmlNodeType.Comment)
        {
          resource[n.Attributes["name"].Value] = n.InnerText;
        }
      }
      HttpRuntime.Cache.Insert(cacheKey, resource, new CacheDependency(file), DateTime.MaxValue, TimeSpan.Zero);
    }
    private Hashtable GetImages()
    {
      string currentCulture = ResourceManager.CurrentCultureName;
      string defaultCulture = LocalizationConfiguration.GetConfig().DefaultCultureName;
      string cacheKey = "LocalizationImage:" + defaultCulture + ':' + currentCulture;
      if (HttpRuntime.Cache[cacheKey] == null)
      {
        Hashtable resource = new Hashtable();
        LoadImage(resource, defaultCulture, cacheKey);
        if (defaultCulture != currentCulture)
        {
          try
          {
            LoadImage(resource, currentCulture, cacheKey);
          }
          catch (FileNotFoundException)
          {}
        }
      }
      return (Hashtable)HttpRuntime.Cache[cacheKey];
    }
    private void LoadImage(Hashtable resource, string culture, string cacheKey)
    {
      string file = string.Format("{0}\\{1}\\Images.xml", fileName, culture);
      XmlDocument xml = new XmlDocument();
      xml.Load(file);
      foreach (XmlNode n in xml.SelectSingleNode("Images"))
      {
        if (n.NodeType != XmlNodeType.Comment)
        {
          LocalizedImageData data = new LocalizedImageData();
          data.Alt = n.InnerText;
          data.Height = Convert.ToInt32(n.Attributes["height"].Value);
          data.Width = Convert.ToInt32(n.Attributes["width"].Value);
          resource[n.Attributes["name"].Value] = data;
        }
      }
      HttpRuntime.Cache.Insert(cacheKey, resource, new CacheDependency(file), DateTime.MaxValue, TimeSpan.Zero);
    }
    #endregion 
  }
}