C# 从数据库中获取应用程序设置&；隐藏物

在我的办公室，人们认为我们应该将Web.Config的AppSettings放入数据库。因此，我创建了以下内容，但对代码的几个方面有一些疑问

所以我的问题是：
实用程序类中包含“Cache Cache=new Cache（）”的行可能是错误的，因为它创建了一个新的缓存对象

问：那么，我应该为这条线做些什么

…非常感谢您的帮助

总体目标是能够打这样的电话：

Utility.GetConfigurationValue(ConfigurationSection.AppSettings, "myVariable");

public static class Utility
{
    #region "Configurations"

    public static String GetConfigurationValue(ConfigurationSection section, String key)
    {
        Configurations config = new Configurations();
        Cache cache = new Cache(); // <--- This is probably wrong!!!!

        if (!cache.TryGetItemFromCache<Configurations>(out config))
        {
            config.List(SNCLavalin.US.Common.Enumerations.ConfigurationSection.AppSettings);
            cache.AddToCache<Configurations>(config, DateTime.Now.AddMinutes(15));
        }

        var result = (from record in config
                      where record.Key == key
                      select record).FirstOrDefault();

        return (result == null) ? null : result.Value;
    }

    #endregion
}

public static class Extensions
{
    #region "System.Web.Caching"

    public static void Remove<T>(this Cache cache) where T : class
    {
        cache.Remove(typeof(T).Name);
    }
    public static void AddToCache<T>(this Cache cache, object item, DateTime absoluteExpiration) where T : class
    {
        T outItem = null;
        if (cache.TryGetItemFromCache<T>(out outItem))
            return;

        cache.Insert(typeof(T).Name,
                item,
                null,
                absoluteExpiration,
                System.Web.Caching.Cache.NoSlidingExpiration,
                System.Web.Caching.CacheItemPriority.Normal,
                null);
    }
    public static bool TryGetItemFromCache<T>(this Cache cache, out T item) where T : class
    {
        item = cache.Get(typeof(T).Name) as T;
        return item != null;
    }

    #endregion
}

public class Configurations : List<Configuration>
{
    #region CONSTRUCTORS

    public Configurations() : base()
    {
        initialize();
    }
    public Configurations(int capacity) : base(capacity)
    {
        initialize();
    }
    public Configurations(IEnumerable<Configuration> collection) : base(collection)
    {
        initialize();
    }

    #endregion

    #region PROPERTIES & FIELDS

    private Crud _crud;

    #endregion

    #region EVENTS
    #endregion

    #region METHODS

    private void initialize()
    {
        _crud = new Crud("CurrentDbConnection");
    }

    public Configurations List(ConfigurationSection section)
    {
        using (DbCommand dbCommand = _crud.Db.GetStoredProcCommand("spa_LIST_SecConfiguration"))
        {
            _crud.Db.AddInParameter(dbCommand, "@Section", DbType.String, section.ToString());

            _crud.List(dbCommand, PopulateFrom);
        }

        return this;
    }

    public void PopulateFrom(DataTable table)
    {
        this.Clear();

        foreach (DataRow row in table.Rows)
        {
            Configuration instance = new Configuration();
            instance.PopulateFrom(row);
            this.Add(instance);
        }
    }

    #endregion
}

…并让它自动从缓存或数据库中检索。

实用程序代码：

Utility.GetConfigurationValue(ConfigurationSection.AppSettings, "myVariable");

public static class Utility
{
    #region "Configurations"

    public static String GetConfigurationValue(ConfigurationSection section, String key)
    {
        Configurations config = new Configurations();
        Cache cache = new Cache(); // <--- This is probably wrong!!!!

        if (!cache.TryGetItemFromCache<Configurations>(out config))
        {
            config.List(SNCLavalin.US.Common.Enumerations.ConfigurationSection.AppSettings);
            cache.AddToCache<Configurations>(config, DateTime.Now.AddMinutes(15));
        }

        var result = (from record in config
                      where record.Key == key
                      select record).FirstOrDefault();

        return (result == null) ? null : result.Value;
    }

    #endregion
}

public static class Extensions
{
    #region "System.Web.Caching"

    public static void Remove<T>(this Cache cache) where T : class
    {
        cache.Remove(typeof(T).Name);
    }
    public static void AddToCache<T>(this Cache cache, object item, DateTime absoluteExpiration) where T : class
    {
        T outItem = null;
        if (cache.TryGetItemFromCache<T>(out outItem))
            return;

        cache.Insert(typeof(T).Name,
                item,
                null,
                absoluteExpiration,
                System.Web.Caching.Cache.NoSlidingExpiration,
                System.Web.Caching.CacheItemPriority.Normal,
                null);
    }
    public static bool TryGetItemFromCache<T>(this Cache cache, out T item) where T : class
    {
        item = cache.Get(typeof(T).Name) as T;
        return item != null;
    }

    #endregion
}

public class Configurations : List<Configuration>
{
    #region CONSTRUCTORS

    public Configurations() : base()
    {
        initialize();
    }
    public Configurations(int capacity) : base(capacity)
    {
        initialize();
    }
    public Configurations(IEnumerable<Configuration> collection) : base(collection)
    {
        initialize();
    }

    #endregion

    #region PROPERTIES & FIELDS

    private Crud _crud;

    #endregion

    #region EVENTS
    #endregion

    #region METHODS

    private void initialize()
    {
        _crud = new Crud("CurrentDbConnection");
    }

    public Configurations List(ConfigurationSection section)
    {
        using (DbCommand dbCommand = _crud.Db.GetStoredProcCommand("spa_LIST_SecConfiguration"))
        {
            _crud.Db.AddInParameter(dbCommand, "@Section", DbType.String, section.ToString());

            _crud.List(dbCommand, PopulateFrom);
        }

        return this;
    }

    public void PopulateFrom(DataTable table)
    {
        this.Clear();

        foreach (DataRow row in table.Rows)
        {
            Configuration instance = new Configuration();
            instance.PopulateFrom(row);
            this.Add(instance);
        }
    }

    #endregion
}

---

}

您已经正确识别了问题-当前代码在每次调用

GetConfigurationValue

时都会创建一个新的

缓存

实例，这会破坏缓存的目的。您需要使缓存实例保持静态，而不是每次都创建一个新实例

public static class Utility
{
    private static Cache cache = new Cache();  // Static class variable

    #region "Configurations"

    public static String GetConfigurationValue(ConfigurationSection section, String key)
    {
        Configurations config = new Configurations();
        // Cache cache = new Cache(); --- removed

        ...
    }
}

---

答案附录：
我确实（事实上）需要将缓存变量指向其他对象。直到我在实用程序类中执行以下操作，它才起作用

private static Cache cache = System.Web.HttpRuntime.Cache;

---

为什么认为我们应该将应用程序设置放在数据库中？它会在应用程序启动后被缓存。@Frennky：谢谢你的评论……我的老板认为我们必须从数据库中获取所有应用程序设置，原因有二：更改web.config中的任何内容会引导人们离开应用程序；人们在发布时不断地破坏web.config。因此，这是我在这个问题上的第一次尝试。所以…对上述问题的任何评论都会很好！非常感谢你…我今天会尝试的！起初，我想我需要指向一个已经存在的物体。但我认为HttpContext.Current.Cache将是传递和使用的错误对象…所以我在这里提示大家。再次感谢！