/// <summary>
/// 获取当前应用程序指定CacheKey的Cache对象值
/// </summary>
/// <param name="CacheKey">索引键值</param>
/// <returns>返回缓存对象</returns>
public static object GetCache(string CacheKey)
{
    System.Web.Caching.Cache objCache = HttpRuntime.Cache;
    return objCache[CacheKey];
}
/// <summary>
/// 设置以缓存依赖的方式缓存数据
/// </summary>
/// <param name="CacheKey">索引键值</param>
/// <param name="objObject">缓存对象</param>
/// <param name="cacheDepen">依赖对象</param>
public static void SetCache(string CacheKey, object objObject, System.Web.Caching.CacheDependency dep)
{
    System.Web.Caching.Cache objCache = HttpRuntime.Cache;
    objCache.Insert(
        CacheKey,
        objObject,
        dep,
        System.Web.Caching.Cache.NoAbsoluteExpiration, //从不过期
        System.Web.Caching.Cache.NoSlidingExpiration, //禁用可调过期
        System.Web.Caching.CacheItemPriority.Default,
        null);
}
protected void Page_Load(object sender, EventArgs e)
{
    string CacheKey = "cachetest";
    object objModel = GetCache(CacheKey);//从缓存中获取
    if (objModel == null) //缓存里没有
    {
        objModel = DateTime.Now;//把当前时间进行缓存
        if (objModel != null)
        {
            //依赖 C:\\test.txt 文件的变化来更新缓存
            System.Web.Caching.CacheDependency dep = new System.Web.Caching.CacheDependency("C:\\test.txt");
            SetCache(CacheKey, objModel, dep);//写入缓存
        }
    } 
    Label1.Text = objModel.ToString();
}