xmlcatalogprovider.cs

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using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Xml;
using System.Xml.Schema;
using System.IO;
using System.Collections.Generic;
/// <summary>
///产品和分类的XML数据存
/// </summary>
public class XmlCatalogProvider : CatalogProvider
{
    private string _xmlFile;
    private string _xsdFile;

    //构造函数，从Web.Config配置文件中获取Xml文件和Schema文件。
    public XmlCatalogProvider()
    {
        SmallBusinessDataProvidersSection sec = (ConfigurationManager.GetSection("SmallBusinessDataProviders")) as SmallBusinessDataProvidersSection;
        string xmlFile = sec.CatalogProviders[sec.CatalogProviderName].Parameters["dataFile"];
        string xsdFile = sec.CatalogProviders[sec.CatalogProviderName].Parameters["schemaFile"];
        //将文件路径映射为网站虚拟路径。
        _xmlFile = HttpContext.Current.Request.MapPath("~/App_Data/" + xmlFile);
        _xsdFile = HttpContext.Current.Request.MapPath("~/App_Data/schemas/" + xsdFile);
    
    }
    /// <summary>
    /// 返回指定分类ID的子分类ID列表
    /// 如果分类ID为空，则返回顶层分类的列表
    /// </summary>
    public override List<Category> GetChildCategories(string parentCategoryId)
    {        
        List<Category> list = new List<Category>();
        if (String.IsNullOrEmpty(parentCategoryId)) parentCategoryId = "NULL";
        //调用Util静态公共类的ReadAndValiDateXml方法从Xml和Schema文件中读取
        //XML数据并返回一个DataSet对象。
        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile,_xsdFile);
        //表按照在DataSet中的顺序，Category|childItemId|item.        
        DataTable categoryTbl = dataSet.Tables[0];
        //遍历Category表中的行信息。
        foreach (DataRow r in categoryTbl.Rows)
        {
            if ((string)r["parentCategoryId"] == parentCategoryId) // match found
            {
                if (r["id"] is DBNull || r["visible"] is DBNull || r["title"] is DBNull)
                    throw new InvalidOperationException(Messages.CategoryRequiredAttributesMissing);
                //使用DataRow中的数据赋值给Category对象。
                Category curr = new Category((string)r["id"], Boolean.Parse((string)r["visible"]), (string)r["title"]);
                curr.Description =  (r["description"] is DBNull)? String.Empty : (string)r["description"];
                curr.ImageUrl =     (r["imageUrl"] is DBNull)  ? String.Empty : (string)r["imageUrl"];
                curr.ImageAltText = (r["imageAltText"] is DBNull)  ? String.Empty : (string)r["imageAltText"];
                list.Add(curr);
            }
        }
        //返回List<Category>对象
        return list;
    }
    /// <summary>
    /// 从一个指定的分类ID中返回产品列表
    /// 如果分类ID为空，则返回一个空列表
    /// </summary>
    public override List<Item> GetChildItems(string parentCategoryId)
    {
        List<Item> itemList = new List<Item>();
        if (String.IsNullOrEmpty(parentCategoryId)) return itemList;
        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile);

        //根据指定的分类ID查找产品索引。
        DataTable categoryTbl = dataSet.Tables[0];
        int index=-1;
        int counter =0;
        foreach (DataRow r in categoryTbl.Rows)
        {   
            if ((string)r["id"] == parentCategoryId)
            {
                index = counter;
                break;
            }
            counter++;
        }
        //保存子产品ID号列表然后构造产品对象。
        DataTable categorizationTbl = dataSet.Tables[1];
        List<String> childItemIds = new List<String>(); 
        foreach (DataRow r in categorizationTbl.Rows)
        {
            if ((int)r["category_Id"] == index)
            {
                childItemIds.Add((string)r["childItemId_Text"]);
            }
        }
        //遍历item表。      
        DataTable itemsTbl = dataSet.Tables[2];
        Item curr;
        foreach (DataRow r in itemsTbl.Rows)
        {
            if (childItemIds.Contains((string)r["id"]))
            {
                if (r["id"] is DBNull || r["visible"] is DBNull || r["title"] is DBNull)
                    throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);
                curr = new Item((string)r["id"],
                                        Boolean.Parse((string)r["visible"]),
                                        (string)r["title"]);
                curr.Description    = (r["description"] is DBNull) ? String.Empty : (string)r["description"];
                curr.Price          = (r["inStock"] is DBNull) ? Double.MinValue : Double.Parse((string)r["price"]);
                curr.InStock        = (r["inStock"] is DBNull) ? true : Boolean.Parse((string)r["inStock"]);
                curr.ImageUrl       = (r["imageUrl"] is DBNull) ? String.Empty : (string)r["imageUrl"];
                curr.ImageAltText   = (r["imageAltText"] is DBNull) ? String.Empty : (string)r["imageAltText"];
                itemList.Add(curr);
            }
        }
        return itemList; 
    }
    ///<summary>
    /// 返回指定产品ID号的产品
    ///</summary>
    public override Item GetItem(string itemId)
    {
        if (String.IsNullOrEmpty(itemId)) return null;
        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile);

        DataTable itemsTbl = dataSet.Tables[2];
        Item curr=null;
        foreach (DataRow r in itemsTbl.Rows)
        {
            if (r["id"] is DBNull )
                throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);

            if(itemId == (string)r["id"]) 
            {
                // ID号不能为空。
                if (r["visible"] is DBNull || r["title"] is DBNull)
                    throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);

                curr = new Item((string)r["id"],Boolean.Parse((string)r["visible"]),(string)r["title"]);
                curr.Description = (r["description"] is DBNull) ? String.Empty : (string)r["description"];
                curr.Price = (r["price"] is DBNull) ? Double.MinValue : Double.Parse((string)r["price"]);
                curr.InStock = (r["inStock"] is DBNull) ? true : Boolean.Parse((string)r["inStock"]);
                curr.ImageUrl = (r["imageUrl"] is DBNull) ? String.Empty : (string)r["imageUrl"];
                curr.ImageAltText = (r["imageAltText"] is DBNull) ? String.Empty : (string)r["imageAltText"];
            }
        }
        return curr;
    }
}