网上购物系统（Task006）——用户界面层公共函数集WebUtility

频繁的数据库操作，需要一个公共的数据库操作函数集(DBUtility中的SQLHelper.cs)；频繁的用户界面操作，也需要一个公共函数集WebUtility.cs。因为频繁，这个类及类中的函数，也做成了静态的。

一、App_Code中添加类WebUtility.cs，并在类中添加函数GetCategoryName()

[csharp] using System;
using System.Configuration;
using System.Web;
using System.Web.Caching;

using WestGarden.DAL;

namespace WestGarden.Web
{
    public static class WebUtility
    {
        private const string CATEGORY_NAME_KEY = "category_name_{0}";
        private static readonly bool enableCaching = bool.Parse(ConfigurationManager.AppSettings["EnableCaching"]);

        public static string GetCategoryName(string categoryId)
        {
            Category category = new Category();
            if (!enableCaching)
                return category.GetCategory(categoryId).Name;

            string cacheKey = string.Format(CATEGORY_NAME_KEY, categoryId);

            string data = (string)HttpRuntime.Cache[cacheKey];
            if (data == null)
            {
                int cacheDuration = int.Parse(ConfigurationManager.AppSettings["CategoryCacheDuration"]);

                data = category.GetCategory(categoryId).Name;

                HttpRuntime.Cache.Add(cacheKey, data, null, DateTime.Now.AddHours(cacheDuration), Cache.NoSlidingExpiration, CacheItemPriority.High, null);
            }
            return data;
        }
    }
}
using System;
using System.Configuration;
using System.Web;
using System.Web.Caching;

using WestGarden.DAL;

namespace WestGarden.Web
{
    public static class WebUtility
    {
        private const string CATEGORY_NAME_KEY = "category_name_{0}";
        private static readonly bool enableCaching = bool.Parse(ConfigurationManager.AppSettings["EnableCaching"]);

        public static string GetCategoryName(string categoryId)
        {
            Category category = new Category();
            if (!enableCaching)
                return category.GetCategory(categoryId).Name;

string cacheKey = string.Format(CATEGORY_NAME_KEY, categoryId);

            string data = (string)HttpRuntime.Cache[cacheKey];
            if (data == null)
            {
                int cacheDuration = int.Parse(ConfigurationManager.AppSettings["CategoryCacheDuration"]);

data = category.GetCategory(categoryId).Name;

                HttpRuntime.Cache.Add(cacheKey, data, null, DateTime.Now.AddHours(cacheDuration), Cache.NoSlidingExpiration, CacheItemPriority.High, null);
            }
            return data;
        }
    }
}

1、这个函数功能是获取类别名称，获取类别需要进行一下判断，如果允许Cache缓存，就从Cache中获取；如果不允许，就从数据库中查询。因些，使用这个函数需要在Web.config中添加两个设置，是否允许Cache以及Cache的生命期。

[csharp] <add key="EnableCaching" value="true"/>

<add key="CategoryCacheDuration" value="12"/>
<add key="EnableCaching" value="true"/>

2、这个函数如果从数据库进行查询，需要调用DAL中的GetCategory()函数，为此，需要在Category.cs中添加函数GetCategory()

[csharp] public CategoryInfo GetCategory(string categoryId)
{
    CategoryInfo category = null;

    SqlParameter parm = new SqlParameter(PARM_CATEGORY_ID, SqlDbType.VarChar, 20);
    parm.Value = categoryId;

    using (SqlDataReader rdr = SqlHelper.ExecuteReader(SqlHelper.ConnectionStringLocalTransaction, CommandType.Text, SQL_SELECT_CATEGORIES, parm))
    {
        if (rdr.Read())
            category = new CategoryInfo(rdr.GetString(0), rdr.GetString(1), rdr.GetString(2));
        else
            category = new CategoryInfo();
    }
    return category;
}
        public CategoryInfo GetCategory(string categoryId)
        {
            CategoryInfo category = null;

SqlParameter parm = new SqlParameter(PARM_CATEGORY_ID, SqlDbType.VarChar, 20);
parm.Value = categoryId;

            using (SqlDataReader rdr = SqlHelper.ExecuteReader(SqlHelper.ConnectionStringLocalTransaction, CommandType.Text, SQL_SELECT_CATEGORIES, parm))
            {
                if (rdr.Read())
                    category = new CategoryInfo(rdr.GetString(0), rdr.GetString(1), rdr.GetStrin

补充：Web开发 , ASP.Net ,