缓存

MVCOutputCache的用法

 

 

[OutputCache(Duration = 10, VaryByParam = "none")]

        public ActionResult Index()

        {

            ViewData["Time"] = DateTime.Now;

            return View();

        }

以上代码的意思就是说在10秒以内,数据是从缓存里面读取

 

 

也可以使用配置文件来做,这样更便于管理,如下:

[OutputCache(CacheProfile = "MyProfile")]

        public ActionResult Index()

        {

            ViewData["Time"] = DateTime.Now;

            return View();

        }

 

配置文件:

<system.web>

    <caching>

      <outputCacheSettings>

        <outputCacheProfiles>

          <add name="cache600" duration="600s" varyByParam="none"/>

        </outputCacheProfiles>

      </outputCacheSettings>

    </caching>

 

 页面级缓存

  [OutputCache(CacheProfile="cache600")]
        public ViewResult Index()
        {
            Response.Cache.SetOmitVaryStar(true);

 

          

         }

 数据级缓存

 string key = "DrivinginfoServiceList" + pagenumber.ToString() + pagesize.ToString() + whe + type + couts.ToString();
                       
                        if (Command.DataCache.GetCache(key) != null)
                        {
                            return (IEnumerable<DrivinginfoRecord>)Command.DataCache.GetCache(key);
                        }
                        else
                        {
                            Command.DataCache.SetCache(key, db.DrivinginfoRecords.OrderByDescending(c => c.PubDate).ToList();
                            return (IEnumerable<DrivinginfoRecord>)Command.DataCache.GetCache(key);
                        }

 

 

  using System.Web.Caching;       

 

 

 /// <summary>
        /// 清理全部缓存
        /// </summary>
        /// <returns></returns>
     
        public ActionResult ClearCache()
        {
            //清理数据集 缓存
            System.Web.Caching.Cache _cache = HttpRuntime.Cache;
            IDictionaryEnumerator CacheEnum = _cache.GetEnumerator();

            while (CacheEnum.MoveNext())
            {
                _cache.Remove(CacheEnum.Key.ToString());
            }
         
            //清理页面缓存

            //不起作用
            //OutputCache.Providers.Clear();
            //System.Web.Caching.OutputCache.Providers.Clear();

 

            //有作用的

            //HttpRuntime下的CacheInternal属性(Internal的,内存中是CacheMulti类型)是ObjectDataSource等DataSource保存缓存的管理器
            //因为CacheInternal、_caches、_entries等都是internal或者private的,所以只能通过反射调用,而且可能会随着.Net升级而失效
            object cacheIntern = Command.DataCache.GetPropertyValue(typeof(HttpRuntime), "CacheInternal") as IEnumerable;
            //_caches是CacheMulti中保存多CacheSingle的一个IEnumerable字段。
            IEnumerable _caches =Command.DataCache.GetFieldValue(cacheIntern, "_caches") as IEnumerable;
            foreach (object cacheSingle in _caches)
            {
                Command.DataCache.ClearCacheInternal(cacheSingle);
            }

            string script = String.Format("<script>alert('缓存清除成功');location.href='{0}'</script>", Url.Action("CarAdmin", "new"));
            return Content(script, "text/html");


        }

 

相关文章:http://www.cnblogs.com/dudu/archive/2012/08/27/asp_net_mvc_outputcache.html

 

          http://blog.csdn.net/vrwind/article/details/7167943

 

          http://www.cnblogs.com/dudu/archive/2011/11/03/outputcache_Bug_vary.html

 

          http://513394217.blog.163.com/blog/static/109791186200981171538616/

 

          http://www.cnblogs.com/xzf158/archive/2009/01/07/1371179.html

 

清除ASP.Net缓存

http://www.cnblogs.com/rupeng/archive/2010/08/05/1793499.html

在网站中要做一个清理缓存的功能(也就是在缓存为到期之前就强制缓存过期),程序中有的地方使用的HttpRuntime.Cache来做的缓存,而和数据库交互部分则使用ObjectDataSource提供的缓存机制。清理HttpRuntime.Cache的缓存很简单,只要

List<string> keys = new List<string>();
            // retrieve application Cache enumerator
            IDictionaryEnumerator enumerator = HttpRuntime.Cache.GetEnumerator();
            // copy all keys that currently exist in Cache
            while (enumerator.MoveNext())
            {
                keys.Add(enumerator.Key.ToString());
            }
            // delete every key from cache
            for (int i = 0; i < keys.Count; i++)
            {
                HttpRuntime.Cache.Remove(keys[i]);
            }

就可以了。

本以为ObjectDataSource等数据源的缓存也是保存在HttpRuntime.Cache中,经过测试没想到竟然不是,因为执行上面的代码以后ObjectDataSource仍然是从缓存读取数据。

使用Reflector反编译发现ObjectDataSource是使用HttpRuntime.CacheInternal来实现的缓存,气氛呀,为什么微软总爱搞“特殊化”,对外提供一个Cache用,自己偷偷用CacheInternal做缓存。CacheInternal是internal的,因此没法直接写代码调用,同时CacheInternal中也没提供清空缓存的方法,只能通过实验发现_caches._entries是保存缓存的Hashtable,因此就用反射的方法调用CacheInternal,然后拿到_caches._entries,最后clear才算ok。

最终代码如下:

            //HttpRuntime下的CacheInternal属性(Internal的,内存中是CacheMulti类型)是ObjectDataSource等DataSource保存缓存的管理器
            //因为CacheInternal、_caches、_entries等都是internal或者private的,所以只能通过反射调用,而且可能会随着.Net升级而失效
            object cacheIntern = CommonHelper.GetPropertyValue(typeof(HttpRuntime), "CacheInternal") as IEnumerable;
            //_caches是CacheMulti中保存多CacheSingle的一个IEnumerable字段。
            IEnumerable _caches = CommonHelper.GetFieldValue(cacheIntern, "_caches") as IEnumerable;
            foreach (object cacheSingle in _caches)
            {
                ClearCacheInternal(cacheSingle);
            }

        private static void ClearCacheInternal(object cacheSingle)
        {
            //_entries是cacheSingle中保存缓存数据的一个private Hashtable
            Hashtable _entries = CommonHelper.GetFieldValue(cacheSingle, "_entries") as Hashtable;
            _entries.Clear();
        }

/// <summary>
        /// 得到type类型的静态属性propertyName的值
        /// </summary>
        /// <param name="type"></param>
        /// <param name="propertyName"></param>
        /// <returns></returns>
        public static object GetPropertyValue(Type type, string propertyName)
        {
            foreach (PropertyInfo rInfo in type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance))
            {
                if (rInfo.Name == propertyName)
                {
                    return rInfo.GetValue(null, new object[0]);
                }
            }
            throw new Exception("无法找到属性:" + propertyName);
        }

        /// <summary>
        /// 得到object对象的propertyName属性的值
        /// </summary>
        /// <param name="obj"></param>
        /// <param name="propertyName"></param>
        /// <returns></returns>
        public static object GetPropertyValue(object obj, string propertyName)
        {
            Type type = obj.GetType();
            foreach (PropertyInfo rInfo in type.GetProperties(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance))
            {
                if (rInfo.Name == propertyName)
                {
                    return rInfo.GetValue(obj, new object[0]);
                }
            }
            throw new Exception("无法找到属性:" + propertyName);
        }

        public static object GetFieldValue(object obj, string fieldName)
        {
            Type type = obj.GetType();
            foreach (FieldInfo rInfo in type.GetFields(BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance))
            {
                if (rInfo.Name == fieldName)
                {
                    return rInfo.GetValue(obj);
                }
            }
            throw new Exception("无法找到字段:" + fieldName);
        }

上面方法由于是通过crack的方法进行调用,可能有潜在的问题,因此仅供参考。

在google上搜索到另外一篇文章 http://www.msdnkk.hu/Articles/Clear_OutputCache-Minden_oldal_torlese ,由于是匈牙利文的,也看不懂在说什么,不过主干是代码,看他代码的思路和我一样,贴过来也供参考

private void clearOutputCache()
{
    Type ct = this.Cache.GetType();
    FieldInfo cif = ct.GetField( "_cacheInternal", BindingFlags.NonPublic | BindingFlags.Instance );
    Type cmt = Cache.GetType().Assembly.GetType( "System.Web.Caching.CacheMultiple" );
    Type cachekeyType = Cache.GetType().Assembly.GetType( "System.Web.Caching.CacheKey" );
    FieldInfo cachesfield = cmt.GetField( "_caches", BindingFlags.NonPublic | BindingFlags.Instance );

    object cacheInternal = cif.GetValue( this.Cache );
    object caches = cachesfield.GetValue( cacheInternal );

    Type arrayType = typeof( Array );
    MethodInfo arrayGetter = arrayType.GetMethod( "GetValue", new Type[] { typeof( int ) } );
    object cacheSingle = arrayGetter.Invoke( caches, new object[] { 1 } );

    FieldInfo entriesField = cacheSingle.GetType().GetField( "_entries", BindingFlags.Instance | BindingFlags.NonPublic );
    Hashtable entries = (Hashtable) entriesField.GetValue( cacheSingle );

    List<object> keys = new List<object>();
    foreach( object o in entries.Keys )
    {
        keys.Add( o );
    }

    MethodInfo remove = cacheInternal.GetType().GetMethod( "Remove", BindingFlags.NonPublic | BindingFlags.Instance, null,
        new Type[] { cachekeyType, typeof( CacheItemRemovedReason ) }, null );
    foreach( object key in keys )
    {
        remove.Invoke( cacheInternal, new object[] { key, CacheItemRemovedReason.Removed } );
    }
}

 

http://pan.baidu.com/s/17sDeG