当前文件： SmallBusinessStarterKit/App_Code/Catalog/XmlCatalogProvider.cs[6K，2009-6-12 11:54:21]，打开代码结构图

		            
  1using System;
  2using System.Data;
  3using System.Configuration;
  4using System.Web;
  5using System.Xml;
  6using System.Xml.Schema;
  7using System.IO;
  8using System.Collections.Generic;
  9/**//// <summary>
 10///产品和分类的XML数据存
 11/// </summary>
 12public class XmlCatalogProvider : CatalogProvider
 13...{
 14    private string _xmlFile;
 15    private string _xsdFile;
 16
 17    //构造函数，从Web.Config配置文件中获取Xml文件和Schema文件。
 18    public XmlCatalogProvider()
 19    ...{
 20        SmallBusinessDataProvidersSection sec = (ConfigurationManager.GetSection("SmallBusinessDataProviders")) as SmallBusinessDataProvidersSection;
 21        string xmlFile = sec.CatalogProviders[sec.CatalogProviderName].Parameters["dataFile"];
 22        string xsdFile = sec.CatalogProviders[sec.CatalogProviderName].Parameters["schemaFile"];
 23        //将文件路径映射为网站虚拟路径。
 24        _xmlFile = HttpContext.Current.Request.MapPath("~/App_Data/" + xmlFile);
 25        _xsdFile = HttpContext.Current.Request.MapPath("~/App_Data/schemas/" + xsdFile);
 26    
 27    }
 28    /**//// <summary>
 29    /// 返回指定分类ID的子分类ID列表
 30    /// 如果分类ID为空，则返回顶层分类的列表
 31    /// </summary>
 32    public override List<Category> GetChildCategories(string parentCategoryId)
 33    ...{        
 34        List<Category> list = new List<Category>();
 35        if (String.IsNullOrEmpty(parentCategoryId)) parentCategoryId = "NULL";
 36        //调用Util静态公共类的ReadAndValiDateXml方法从Xml和Schema文件中读取
 37        //XML数据并返回一个DataSet对象。
 38        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile,_xsdFile);
 39        //表按照在DataSet中的顺序，Category|childItemId|item.        
 40        DataTable categoryTbl = dataSet.Tables[0];
 41        //遍历Category表中的行信息。
 42        foreach (DataRow r in categoryTbl.Rows)
 43        ...{
 44            if ((string)r["parentCategoryId"] == parentCategoryId) // match found
 45            ...{
 46                if (r["id"] is DBNull || r["visible"] is DBNull || r["title"] is DBNull)
 47                    throw new InvalidOperationException(Messages.CategoryRequiredAttributesMissing);
 48                //使用DataRow中的数据赋值给Category对象。
 49                Category curr = new Category((string)r["id"], Boolean.Parse((string)r["visible"]), (string)r["title"]);
 50                curr.Description =  (r["description"] is DBNull)? String.Empty : (string)r["description"];
 51                curr.ImageUrl =     (r["imageUrl"] is DBNull)  ? String.Empty : (string)r["imageUrl"];
 52                curr.ImageAltText = (r["imageAltText"] is DBNull)  ? String.Empty : (string)r["imageAltText"];
 53                list.Add(curr);
 54            }
 55        }
 56        //返回List<Category>对象
 57        return list;
 58    }
 59    /**//// <summary>
 60    /// 从一个指定的分类ID中返回产品列表
 61    /// 如果分类ID为空，则返回一个空列表
 62    /// </summary>
 63    public override List<Item> GetChildItems(string parentCategoryId)
 64    ...{
 65        List<Item> itemList = new List<Item>();
 66        if (String.IsNullOrEmpty(parentCategoryId)) return itemList;
 67        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile);
 68
 69        //根据指定的分类ID查找产品索引。
 70        DataTable categoryTbl = dataSet.Tables[0];
 71        int index=-1;
 72        int counter =0;
 73        foreach (DataRow r in categoryTbl.Rows)
 74        ...{   
 75            if ((string)r["id"] == parentCategoryId)
 76            ...{
 77                index = counter;
 78                break;
 79            }
 80            counter++;
 81        }
 82        //保存子产品ID号列表然后构造产品对象。
 83        DataTable categorizationTbl = dataSet.Tables[1];
 84        List<String> childItemIds = new List<String>(); 
 85        foreach (DataRow r in categorizationTbl.Rows)
 86        ...{
 87            if ((int)r["category_Id"] == index)
 88            ...{
 89                childItemIds.Add((string)r["childItemId_Text"]);
 90            }
 91        }
 92        //遍历item表。      
 93        DataTable itemsTbl = dataSet.Tables[2];
 94        Item curr;
 95        foreach (DataRow r in itemsTbl.Rows)
 96        ...{
 97            if (childItemIds.Contains((string)r["id"]))
 98            ...{
 99                if (r["id"] is DBNull || r["visible"] is DBNull || r["title"] is DBNull)
100                    throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);
101                curr = new Item((string)r["id"],
102                                        Boolean.Parse((string)r["visible"]),
103                                        (string)r["title"]);
104                curr.Description    = (r["description"] is DBNull) ? String.Empty : (string)r["description"];
105                curr.Price          = (r["inStock"] is DBNull) ? Double.MinValue : Double.Parse((string)r["price"]);
106                curr.InStock        = (r["inStock"] is DBNull) ? true : Boolean.Parse((string)r["inStock"]);
107                curr.ImageUrl       = (r["imageUrl"] is DBNull) ? String.Empty : (string)r["imageUrl"];
108                curr.ImageAltText   = (r["imageAltText"] is DBNull) ? String.Empty : (string)r["imageAltText"];
109                itemList.Add(curr);
110            }
111        }
112        return itemList; 
113    }
114    /**////<summary>
115    /// 返回指定产品ID号的产品
116    ///</summary>
117    public override Item GetItem(string itemId)
118    ...{
119        if (String.IsNullOrEmpty(itemId)) return null;
120        DataSet dataSet = Util.ReadAndValidateXml(_xmlFile, _xsdFile);
121
122        DataTable itemsTbl = dataSet.Tables[2];
123        Item curr=null;
124        foreach (DataRow r in itemsTbl.Rows)
125        ...{
126            if (r["id"] is DBNull )
127                throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);
128
129            if(itemId == (string)r["id"]) 
130            ...{
131                // ID号不能为空。
132                if (r["visible"] is DBNull || r["title"] is DBNull)
133                    throw new InvalidOperationException(Messages.ItemRequiredAttributesMissing);
134
135                curr = new Item((string)r["id"],Boolean.Parse((string)r["visible"]),(string)r["title"]);
136                curr.Description = (r["description"] is DBNull) ? String.Empty : (string)r["description"];
137                curr.Price = (r["price"] is DBNull) ? Double.MinValue : Double.Parse((string)r["price"]);
138                curr.InStock = (r["inStock"] is DBNull) ? true : Boolean.Parse((string)r["inStock"]);
139                curr.ImageUrl = (r["imageUrl"] is DBNull) ? String.Empty : (string)r["imageUrl"];
140                curr.ImageAltText = (r["imageAltText"] is DBNull) ? String.Empty : (string)r["imageAltText"];
141            }
142        }
143        return curr;
144    }
145} 
146