1、使用缓存

同一个社区的人在同一时间所看到的优惠券记录应该是一样的,而且我们应该允许脏读,我们在12306上面买火车票的时候,经常也会看到显示有票,但是下单又没有了,可能是使用了缓存,那么我们这里其实同样的可以采用缓存来缓解并发问题。

在WebAPI上面加缓存,那么又分为客户端缓存和服务器缓存。而我们知道,在ASP.NET
WebForm和ASP.NET
MVC中都是有页面输出缓存的,而在WebAPI中默认没有,从NuGet上面下载WebApi.OutputCache.V2,然后再API接口上添加 

[CacheOutput(ClientTimeSpan = 5)]//, ServerTimeSpan = 5

我这里没法直接使用服务器输出缓存,那是因为无法捕获缓存变量参数。因为我们API接口的请求参数是string
appParam,字符串类型的,它是一个json对象进过base64位编码,然后再进过url编码生成的字符串。

我们只能解析后,获取社区ID,然后根据社区ID来设置缓存,把社区ID+
pageIndex就作为缓存的Key,考虑到需要缓存的数据量很小,这里我直接使用.NET自带的缓存,引入命名空间:System.Web.Caching;

      private static System.Web.Caching.Cache ObjCache = HttpRuntime.Cache;
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间 
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间(秒)</param>
        public static void SetCacheSeconds(string Key, object Obj, double TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddSeconds(TimeOuts), TimeSpan.Zero);
        }
        /// <summary>
        /// 获取当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <returns>缓存的值</returns>
        public static object GetCache(string Key)
        {
            return ObjCache[Key];
        }

缓存操作类Cache完整代码如下:

mg4355电子游戏 1mg4355电子游戏 2

/*==================================
 * Author:
 * CreateTime:2014-7-15 17:26:29
 * Description:Cache操作类
 ===================================*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Caching;
using System.Runtime.CompilerServices;
using System.Web;
using System.Security.Policy;

namespace SSY.Util
{
    /// <summary>
    /// 缓存处理相关类
    /// </summary>
    public class Cache
    {
        private static System.Web.Caching.Cache ObjCache = HttpRuntime.Cache;
        private static short TimeOut = 720;

        #region 清除指定键值的缓存
        /// <summary>
        /// 清除指定键值的缓存
        /// </summary>
        /// <param name="Key">要清除的缓存的key值</param>
        public static void Clear(string Key)
        {
            if (ObjCache[Key] != null)
            {
                ObjCache.Remove(Key);
            }
        }
        #endregion

        #region 返回系统中缓存的个数
        /// <summary>
        /// 返回系统中缓存的个数
        /// </summary>
        /// <returns>缓存个数</returns>
        public static int Count()
        {
            return ObjCache.Count;
        }
        #endregion

        #region 获取当前指定Key的Cache值
        /// <summary>
        /// 获取当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <returns>缓存的值</returns>
        public static object GetCache(string Key)
        {
            return ObjCache[Key];
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值 
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        public static void SetCache(string Key, object Obj)
        {
            ObjCache.Insert(Key, Obj);
        }
        #endregion

        #region 设置当前指定Key的Cache值,并限定过期时间
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间 
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间(分钟)</param>
        public static void SetCache(string Key, object Obj, int TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddMinutes((double)TimeOuts), TimeSpan.Zero);
        }
        /// <summary>
        /// 设置当前指定Key的Cache值,并限定过期时间 
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">超时时间(秒)</param>
        public static void SetCacheSeconds(string Key, object Obj, double TimeOuts)
        {
            ObjCache.Insert(Key, Obj, null, System.DateTime.Now.AddSeconds(TimeOuts), TimeSpan.Zero);
        }
        #endregion

        #region 设置当前指定Key的Cache值,依赖文件过期
        /// <summary>
        /// 设置当前指定Key的Cache值,依赖文件过期 
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="Files">相对地址,例如"~/files.xml"</param>
        public static void SetCache(string Key, object Obj, string Files)
        {
            CacheDependency cacheDep = new CacheDependency(System.Web.HttpContext.Current.Server.MapPath(Files),System.DateTime.Now);
            SetCache(Key, Obj, TimeOut, cacheDep, CacheItemPriority.High);
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="Priority">撤销缓存的优先值,此参数的值取自枚举变量“CacheItemPriority”,优先级低的数据项将先被删除。此参数主要用在缓存退出对象时.</param>
        public static void SetCache(string Key, object Obj, CacheItemPriority Priority)
        {
            SetCache(Key, Obj, TimeOut, null, Priority);
        }
        #endregion

        #region 设置当前指定Key的Cache值
        /// <summary>
        /// 设置当前指定Key的Cache值
        /// </summary>
        /// <param name="Key">缓存Key</param>
        /// <param name="Obj">缓存的值</param>
        /// <param name="TimeOuts">一个TimeSpan,表示缓存参数将在多长时间以后被删除</param>
        /// <param name="CacheDep">缓存的依赖项,需要一个CacheDependency,可初始化一个</param>
        /// <param name="Priority">撤销缓存的优先值,此参数的值取自枚举变量“CacheItemPriority”,优先级低的数据项将先被删除。此参数主要用在缓存退出对象时</param>
        public static void SetCache(string Key, object Obj, int TimeOuts, CacheDependency CacheDep, CacheItemPriority Priority)
        {
            ObjCache.Insert(Key, Obj, CacheDep, System.DateTime.MaxValue, TimeSpan.FromHours((double)TimeOuts), Priority, null);
        }
        #endregion
    }
}

View Code

修改API接口代码:

           #region added by zouqj 2017-3-7
           var result = Util.Cache.GetCache(CommunityID+ pageIndex) as Result<List<GetAvailableCouponsModel>>;
           if (result==null) //不存在则写入缓存
           {
               //组装参数
               Dictionary<string, string> inParams = new Dictionary<string, string>();
               inParams.Add("UserId", userId);
               inParams.Add("PageIndex", pageIndex);
               inParams.Add("PageSize", pageSize);
               inParams.Add("CommunityID", CommunityID+ pageIndex);
               ...

               RequestParam RequestParam = GetRequestParam(methodName, inParams, AuthenticationId);
               var jsonContent = JsonConvert.SerializeObject(RequestParam);
               result = DoPost<List<GetAvailableCouponsModel>>(jsonContent, PostUrl);

               Util.Cache.SetCacheSeconds(CommunityID, result, 10); //写入缓存
           }
           return result;

  数据缓存Data caching

2、改为存储过程实现

因为这个接口的业务逻辑比较复杂,之前的Linq代码写了好长一大串,获取的记录数很多,而且还是在内存中进行分页实现,所以我将原来的LINQ实现代码修改为分页存储过程实现。

存储过程代码如下:

mg4355电子游戏 1mg4355电子游戏 4

------------------------------------------创建领券中心存储过程 created by zouqj-2017-3-1-----------------------------------
IF EXISTS(Select Name From Sysobjects Where Name='usp_GetAvailableCoupons' And Xtype='P')
DROP PROCEDURE usp_GetAvailableCoupons
GO
CREATE PROC usp_GetAvailableCouponsl
(
@PageIndex int, --页码
@PageSize int, --每页容纳的记录数
@Sort NVARCHAR(50), --排序字段及规则,不用加order by
@hostName nvarchar(100),--服务器地址
@CommunityID UNIQUEIDENTIFIER, --社区
@IsGetCount BIT --是否得到记录总数,1为得到记录总数,0为不得到记录总数,返回记录集
)
AS
-------------------------------定义变量-----------------------
declare @strSql NVARCHAR(max);
DECLARE  @dt datetime2(7) --查询时间
SET @dt=GETDATE();
set nocount on;
----------------------------------------SQL开始--------------------------------------------无分类
IF @IsGetCount=1
BEGIN

SET @strSql=N'SELECT COUNT(*) FROM (SELECT DISTINCT t.CampaignID from
(SELECT 
c.ID AS CampaignID
 FROM MK_Campaign c WITH ( NOLOCK ) INNER JOIN MK_CouponConfig f WITH ( NOLOCK ) ON c.ID=f.CampaignID
           INNER JOIN MK_Coupon p WITH ( NOLOCK ) ON f.CouponID=p.ID
           WHERE f.CouponGetType=2 AND f.ReceiveStartTime <=@dt AND f.ReceiveEndTime>= @dt
           AND c.State=4 --执行中
           AND p.WholeNetwork=1 --全网优惠
UNION ALL
SELECT
    a.[ID] AS CampaignID
    FROM  [dbo].[MK_Campaign] AS a WITH ( NOLOCK )
        INNER JOIN [dbo].[MK_CouponConfig] AS b  WITH ( NOLOCK ) ON a.[ID] = b.[CampaignID]
        AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt) AND (2 = b.[CouponGetType]) AND (4 = a.[State]) 
        INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID]
        INNER JOIN [dbo].[MK_CouponRestriction] AS d  WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]
        LEFT OUTER JOIN [dbo].[MK_CouponRestrictCategory] AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
        LEFT OUTER JOIN [dbo].[MK_CouponRestrictionOrg] AS f WITH ( NOLOCK ) ON d.[ID] = f.[CouponRestrictionID]
        INNER JOIN [dbo].[ViewOrganizationCommunityForInterface] AS v ON f.[OrgID] = v.[ID]    
    where v.CommunityID=@CommunityID  and 1 = d.[Type]
UNION ALL
SELECT 
   a.ID AS CampaignID
   FROM MK_Campaign a  WITH ( NOLOCK ) 
             INNER JOIN MK_CouponConfig b WITH ( NOLOCK ) ON a.ID=b.CampaignID AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >=@dt) 
             INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID] and (2 = b.[CouponGetType]) AND (4 = a.[State]) 
             INNER JOIN [dbo].[MK_CouponRestriction] AS d WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]  AND (2 = d.[Type]) 
             LEFT OUTER JOIN MK_CouponRestrictionProduct AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID] 
             LEFT OUTER JOIN SL_Product AS f WITH ( NOLOCK ) ON (e.ProductID = f.ID)
             INNER JOIN ViewOrganizationCommunityForInterface v ON v.ID=f.PublisherID
   where v.CommunityID=@CommunityID
   ) t
 ) AS tt'
----------------------------------------------------------------------------------
END
ELSE
BEGIN
SET @strSql=N'SELECT DISTINCT t.* from(
SELECT 
          c.ID AS CampaignID,
          c.Name AS CampaignName,
          f.ValidityStartTime AS CampaignStartTime,
          f.ValidityEndTime AS CampaignEndTime,
          p.Name AS CouponsName,
          p.Price AS CouponsAmount,
          (CASE WHEN p.IsLimited =1 THEN 1 ELSE 2 END) AS IsLimited,
          p.FullAmount AS MinAmount,
          f.ValidityEndTime AS CouponsEndTime,
          f.ValidityStartTime AS CouponsStartTime,
          (CASE WHEN f.IsRepeateGet =1 THEN 1 ELSE 2 END) AS IsCanRepeatedReceive,
          f.ReceiveAddress AS ReceiveAddress,
          f.ReceiveEndTime AS ReceiveEndTime,
          f.ReceiveStartTime AS ReceiveStartTime,
          f.ReceiveMode AS ReceiveMethod,
          f.ProvideNum AS ReceiveNum,
          p.CreateTime AS CreateTime,
          p.Price AS Price,
          f.RemainCouponNum AS RemainCouponNum,
          f.ID AS CouponConfigId,
          p.WholeNetwork AS CouponsType,
          (CASE WHEN f.IconUrl IS NULL THEN N'''' WHEN f.IconUrl=N'''' THEN N'''' ELSE @hostName+f.IconUrl END) AS IconUrl 
FROM MK_Campaign c WITH ( NOLOCK ) 
                 INNER JOIN MK_CouponConfig f WITH ( NOLOCK ) ON c.ID=f.CampaignID
                 INNER JOIN MK_Coupon p WITH ( NOLOCK ) ON f.CouponID=p.ID
          WHERE f.CouponGetType=2 AND f.ReceiveStartTime <= @dt AND f.ReceiveEndTime>= @dt AND c.State=4 AND p.WholeNetwork=1 --全网优惠
--
UNION ALL
          SELECT a.[ID] AS CampaignID,
          a.[Name] AS CampaignName, 
          b.[ValidityStartTime] AS CampaignStartTime,
          b.[ValidityEndTime] AS CampaignEndTime, 
          c.[Name] AS CouponsName, 
          c.[Price] AS CouponsAmount, 
          CASE WHEN (c.[IsLimited] = 1) THEN 1 ELSE 2 END AS IsLimited, 
          c.[FullAmount] AS MinAmount, 
          b.[ValidityEndTime] AS CouponsEndTime, 
          b.[ValidityStartTime] AS CouponsStartTime, 
          CASE WHEN (b.[IsRepeateGet] = 1) THEN 1 ELSE 2 END AS IsCanRepeatedReceive, 
          b.[ReceiveAddress] AS [ReceiveAddress], 
          b.[ReceiveEndTime] AS [ReceiveEndTime], 
          b.[ReceiveStartTime] AS [ReceiveStartTime], 
          b.[ReceiveMode] AS ReceiveMethod, 
          b.[ProvideNum] AS ReceiveNum, 
          c.[CreateTime] AS CreateTime, 
          c.[Price] AS Price, 
          b.[RemainCouponNum] AS RemainCouponNum, 
          b.[ID] AS CouponConfigId, 
          e.[Type] AS CouponsType, 
          CASE WHEN (b.[IconUrl] = N'''' OR b.[IconUrl] IS NULL) THEN N'''' ELSE @hostName+b.[IconUrl] END AS IconUrl
                    FROM  [dbo].[MK_Campaign] AS a WITH ( NOLOCK )
                        INNER JOIN [dbo].[MK_CouponConfig] AS b  WITH ( NOLOCK ) ON a.[ID] = b.[CampaignID] AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt) AND (2 = b.[CouponGetType]) AND (4 = a.[State]) 
                        INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID]
                        INNER JOIN [dbo].[MK_CouponRestriction] AS d  WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]
                        LEFT OUTER JOIN [dbo].[MK_CouponRestrictCategory] AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID]
                        LEFT OUTER JOIN [dbo].[MK_CouponRestrictionOrg] AS f WITH ( NOLOCK ) ON d.[ID] = f.[CouponRestrictionID]
                        INNER JOIN [dbo].[ViewOrganizationCommunityForInterface] AS v ON f.[OrgID] = v.[ID]    
                    where v.CommunityID=@CommunityID  and 1 = d.[Type]
UNION ALL
SELECT 
       a.ID AS CampaignID,
       a.Name AS CampaignName,
       b.ValidityStartTime AS CampaignStartTime,
       b.ValidityEndTime AS CampaignEndTime,
       c.Name AS CouponsName,
       c.Price AS CouponsAmount,
       (CASE WHEN c.IsLimited=1 then 1 else 2 END) AS IsLimited,
       c.FullAmount AS MinAmount,
       b.ValidityEndTime AS CouponsEndTime,
       b.ValidityStartTime AS CouponsStartTime,
       (case when b.IsRepeateGet=1 then 1 else 2 END) AS IsCanRepeatedReceive,
       b.ReceiveAddress AS ReceiveAddress,
       b.ReceiveEndTime AS ReceiveEndTime,
       b.ReceiveStartTime AS ReceiveStartTime,
       b.ReceiveMode AS ReceiveMethod,
       b.ProvideNum AS ReceiveNum,
       c.CreateTime AS CreateTime,
       c.Price AS Price,
       b.RemainCouponNum AS RemainCouponNum,
       b.ID AS CouponConfigId,
       d.[TYPE] AS CouponsType,
       (CASE WHEN b.IconUrl IS NULL THEN N'''' WHEN b.IconUrl=N'''' THEN N'''' ELSE @hostName+b.IconUrl END) AS IconUrl
   FROM MK_Campaign a  WITH ( NOLOCK ) 
                    INNER JOIN MK_CouponConfig b WITH ( NOLOCK ) ON a.ID=b.CampaignID AND (b.[ReceiveStartTime] <= @dt) AND (b.[ReceiveEndTime] >= @dt) 
                    INNER JOIN [dbo].[MK_Coupon] AS c WITH ( NOLOCK ) ON b.[CouponID] = c.[ID] and (2 = b.[CouponGetType]) AND (4 = a.[State]) 
                    INNER JOIN [dbo].[MK_CouponRestriction] AS d WITH ( NOLOCK ) ON c.[ID] = d.[CompainID]  AND (2 = d.[Type]) 
                    LEFT OUTER JOIN MK_CouponRestrictionProduct AS e WITH ( NOLOCK ) ON d.[ID] = e.[CouponRestrictionID] 
                    LEFT OUTER JOIN SL_Product AS f WITH ( NOLOCK ) ON (e.ProductID = f.ID)
                    INNER JOIN ViewOrganizationCommunityForInterface v ON v.ID=f.PublisherID
                    where v.CommunityID=@CommunityID
   ) t
ORDER BY t.Price--@Sort
offset (@PageIndex-1)*@PageSize ROWS  FETCH NEXT @PageIndex*@PageSize ROWS ONLY'
end
--执行SQL
exec sp_executesql @strSql,N'@PageIndex int,@PageSize int,@Sort nvarchar(50),@hostName nvarchar(100),@CommunityID UNIQUEIDENTIFIER,@IsGetCount bit,@dt datetime2(7)',@PageIndex =@PageIndex,@PageSize =@PageSize,@Sort=@Sort,@hostName=@hostName,@CommunityID=@CommunityID,@IsGetCount=@IsGetCount,@dt=@dt
set nocount off;

View Code

这里需要注意的是,存储执行是,先关闭计数,set nocount on;,然后再打开set
nocount off;,这样可以提升性能。还有就是使用WITH ( NOLOCK
)允许脏读,提升查询效率。

这里遇到一个很诡异的问题,我使用exec
sp_executesql
@strSql,N’….’的方式来执行是没有问题的,而如果我使用拼接sql的方式,会报错,因为sql字符串被截断了,只截取到了4000个字符长度,即便我把字符串变量长度设置为nvarchar(max)也没用。

分页方式采用Sqlserver2012以上版本才支持的高效方式:offset … FETCH NEXT
…ROWS ONLY

原来Linq的执行时间测试:

mg4355电子游戏 5BLW.png)mg4355电子游戏 6

我修改为存储过程之后的执行时间测试:

mg4355电子游戏 7

性能差距非常明显。

 

筛选数据

需求:如果数据库中存在OrderNum相同,且IsDefault不同的记录,那么IsDefault值为0的记录将替换值为1的记录(IsDefault值为1的记录不展示)。

mg4355电子游戏 8

由于查出来的数据不多,100条以内,所以我是直接全部查询到List内存中,然后在内存中进行数据过滤的操作,思来想去都觉得我如下的实现方式很low,但是我一时又没想到好的办法,不知道大家有没有好的办法?

            var newList = list.ToList();
            //筛选出哪些排序号有重复
            var orderNumList = newList.GroupBy(g => g.OrderNum).Select(g => new { orderNum = g.Key, count = g.Count() }).Where(g => g.count > 1).Select(s => s.orderNum).ToList();
            var cfList = newList.Where(w => orderNumList.Contains(w.OrderNum)); //获取有重复排序号的记录

            var cfDefaultList = cfList.Where(w => w.IsDefault);  //默认模块记录
            var cfNoDefaultList = cfList.Where(w => w.IsDefault == false); //非默认模块记录

            var intersectedList = from d in cfDefaultList join f in cfNoDefaultList on d.OrderNum equals f.OrderNum where d.IsDefault!= f.IsDefault select d;

            var newIntersectedList = intersectedList.Distinct().ToArray(); //排序号相同,既存在默认记录也存在非默认记录的数据 

                if (newIntersectedList != null && newIntersectedList.Length > 0)
                {
                    for (int i = 0; i < newIntersectedList.Length; i++)
                    {
                        if (newList.Contains(newIntersectedList[i]))
                        {
                            newList.Remove(newIntersectedList[i]);
                        }
                    }
                }
           newList = newList.OrderBy(x => x.OrderNum).ToList();

 以上的newList就代码截图中的数据。

  例子中创建了“Date1” 和 “Date2”缓存。“Date1”
在20秒后过期“Date2”为40秒。但是由于我们注册了移除的回调函数,当“Date1”
或 “Date2”其中一个过期都会执行CachedItemRemoveCallBack
方法,在这个方法中移除了两个缓存条目,ASP.NET还提供了处理缓存条目更新时的回调函数CacheItemUpdateCallback

优化API接口

有一个API接口经常卡顿,而且很不稳定,快的时候2~3秒,慢的时候10秒去了。

接口需求:根据社区ID获取优惠券记录。

分析:

  • 负责给API接口提供数据的系统中,缺少许多索引,存在许多慢查询视图。
  • 原来的LINQ实现方式是在内存中分页,响应速度太慢。
  • 并发请求的情况下,资源占用。

优化思路:

  上面的例子中GetVaryByCustomString()方法根据浏览器的名字创建缓存字符串,ASP.NET会根据不同的浏览器请求创建不同版本的缓存。

 

 

  上面的例子“Date2”缓存对象依赖“Date1”缓存条目,当 “Date1”
对象过期后“Date2” 将会自动过期。CacheDependency(null,
cacheKeys)中的第一个参数为空是由于我们只监视缓存键的更改情况。

  我们可以通过使用Cache.Insert()方法来设置缓存的过期,优先级,依赖项等。

  使用输出缓存,你可以缓存最后输出的HTML页面,当相同的页面再次请求的时候,ASP.NET不会再执行页面的生命周期和相关代码而是直接使用缓存的页面,语法如下:

  通过查询字符串缓存(Cache by Query String )

   在这个例子中页面将被缓存20秒。

  Cache[mg4355电子游戏,”Name”] = data;

protected void Page_Load(object sender, EventArgs e) 

  lblDate.Text = DateTime.Now.ToShortDateString(); 
  lblTime.Text = DateTime.Now.ToLongTimeString(); 
}

  VaryByControl=”EmployeeID”告诉ASP.NET根据控件中声明的EmployeeID属性来创建不同版本的缓存。

  Duration
属性设置页面将被缓存60妙。任何的用户请求都会被缓存,在缓冲的60秒内相同的请求都会直接使用缓存的页面。当缓存过期后ASP.NET会再次执行页面代码并且为下一个60秒创建一个新的HTML缓存。

  自定义缓存(Custom Caching)

 

  %@OutputCacheDuration=”60″VaryByParam=”id;langid”%

  date1 = DateTime.Now;Cache.Insert(“Date1”, date1, null,
DateTime.Now.AddSeconds(20), TimeSpan.Zero);

  上面的缓存技术可以让你很容易的缓存整个页面,如果要缓存指定控件的内容,可以通过指定VaryByControl
属性来完成。

 

  这个方法必须写在global.asax文件中。ASP.NET使用该方法返回的字符串来实现缓存,如果这个方法在不同的请求中返回相同的字符串,ASP.NET就会使用缓存的页面,否则就会生成新的缓存版本。

  这个时候我们可以在VarByParam
属性中指定重要的查询字符串变量的名字,如下:

  ASP.net还提供了另一种灵活的缓存类型:数据缓存。你可以将一些耗费时间的条目加入到一个对象缓存集合中,以键值的方式存储。

  ASP.NET允许我们写一个回调函数,当缓存条目从缓存中移除的时候触发。还可以设置缓存条目的优先级。

 

 

  <%@
OutputCache Duration=”60” VaryByParam=”None”  %>

  在 .ascx.cs 文件加入EmplyeeID属性为ASP.NET 缓存使用。

 

  %@OutputCacheDuration=”20″VaryByControl=”MyControl_1″%

    private int_employeeID; 
  public intEmployeeID 
  { 
  get{ return_employeeID; } 
  set{ _employeeID = value;

  } 
  protected voidPage_Load(objectsender, EventArgs e) 
  { 
  lblDate.Text = DateTime.Now.ToShortDateString(); 
  lblTime.Text = DateTime.Now.ToLongTimeString(); 
  lblEmployeeID.Text = EmployeeID.ToString(); 
  }

  这样,ASP.NET可以根据id” or “langid”来缓存不同的缓存版本。

  你也可以创建自定义的程序来缓存页面。ASP.net提供了一种很便捷的方式来创建自定义缓存,使用VarByCustom属性指定自定义缓存类型的名字。

  ASP.NET允许你设置一个绝对过期时间或滑动过期时间,但不能同时使用。

  上面代码ASP.NET将会缓存MyControl_1控件20分钟。如果要根据一些属性值来缓存控件只需要将OutPutCache指令加入*.ascx页面。

输出缓存Output caching

  2. 数据缓存(Data Caching)

 

    date2 = DateTime.Now; 
  string[] cacheKeys = { “Date1”}; 
  CacheDependency cacheDepn = newCacheDependency(null,
cacheKeys); 
  Cache.Insert(“Date2”, date2,
cacheDepn);

  %@OutputCacheCacheProfile=”ProductItemCacheProfile”VaryByParam=”None”%

  protected void Page_Load(object sender, EventArgs e) 
  { 
  DateTime? date1 = (DateTime?)Cache[“Date1”]; 
  if (!date1.HasValue) // date1 ==
null 
  { 
  date1 = DateTime.Now; 
  Cache.Insert(“Date1”,
date1, null, DateTime.Now.AddSeconds(20),
TimeSpan.Zero, 
  CacheItemPriority.Default, new CacheItemRemovedCallback(CachedItemRemoveCallBack)); 
  } 
  DateTime? date2 = (DateTime?)Cache[“Date2”]; 
  if (!date2.HasValue) // date2 ==
null 
  { 
  date2 = DateTime.Now; 
  Cache.Insert(“Date2”,
date2, null, DateTime.Now.AddSeconds(40),
TimeSpan.Zero, 
  CacheItemPriority.Default, new CacheItemRemovedCallback(CachedItemRemoveCallBack)); 
  } 
  // Set values in labels 
  lblDate.Text = date1.Value.ToShortDateString(); 
  lblTime.Text = date1.Value.ToLongTimeString(); 
  lblDate1.Text = date2.Value.ToShortDateString(); 
  lblTime1.Text = date2.Value.ToLongTimeString(); 
  } 
  private void CachedItemRemoveCallBack(string key, object value, CacheItemRemovedReason reason) 
  { 
  if (key == “Date1” || key == “Date2”) 
  { 
  Cache.Remove(“Date1”); 
  Cache.Remove(“Date2”); 
  } 
  }

<%@ Page Language=”C#” MastERPageFile=”~/MasterPage.master” AutoEventWireup=”true” CodeFile=”OutputCachingTest.aspx.cs” Inherits=”OutputCachingTest” Title=”Page” %> 
<%@ OutputCache Duration=”20″ VaryByParam=”None” %> 
<asp:Content ID=”Content1″ ContentPlaceHolderID=”ContentPlaceHolder1″ runat=”Server”>  
   <div class=”title”>Output
Cache</div> 
   Date: <asp:Label ID=”lblDate” runat=”server” Text=”” /> 
   Time: <asp:Label ID=”lblTime” runat=”server” Text=”” />        
</asp:Content>

  缓存依赖项Cache dependency

<%@Control Language=”C#”AutoEventWireup=”true”CodeFile=”MyControl.ascx.cs” 
Inherits=”Controls_MyControl”%> 
<%@OutputCacheDuration=”20″VaryByControl=”EmployeeID”%>  

 

  缓存依赖项使缓存依赖于其他资源,当依赖项更改时,缓存条目项将自动从缓存中移除。缓存依赖项可以是应用程序的
Cache 中的文件、目录或与其他对象的键。如果文件或目录更改,缓存就会过期。

  public override stringGetVaryByCustomString(HttpContext
context, stringcustom) 
  { 
  if(custom == “browser”) 
  { 
  returncontext.Request.Browser.Browser + 
  context.Request.Browser.MajorVersion; 
  } 
  else 
  { 
  return base.GetVaryByCustomString(context, custom); 
  } 
  }

  在实际应用中页面往往会根据一些参数动态的改变页面的内容。如果你的页面是通过查询字符串来获取信息的,你可以根据查询字符串很容易的缓存页面的不同拷贝。VarByParam=”None”指定ASP.NET只存储缓存页面的一个拷贝。VarByParam=”*”
指定ASP.NET根据不同的查询字符串存储不同的缓存页面。

  1. 输出缓存(Output Caching)

     缓存配置文件(Cache Profile )

  <system.web> 
  <caching> 
    <outputCacheSettings> 
      <outputCacheProfiles> 
        <addname=”ProductItemCacheProfile” duration=”60″/> 
      </outputCacheProfiles> 
    </outputCacheSettings> 
  </caching> 
</system.web>

  你还要创建为缓存生成自定义字符串的方法,如下:

  上面的例子中,在查询字符串中传了不同的ID.ASP.NET为每一个ID都存储了单独的缓存页面。这种方式会有一些问题就是当查询字符串范围很广的时候。

   你可以通过设置 CacheProfile=”ProfileName” 属性 来使用上面的配置:

  回调函数和缓存优先级(Callback Method and Cache Priority)

<%@ OutputCache
Duration=”60″ VaryByParam=”*” %> 
<div align=”right”> 
   <a href=”OutputCachingTest2.aspx”>No
Query String</a> |  
   <a href=”OutputCachingTest2.aspx?id=1″>ID
1</a> |  
   <a href=”OutputCachingTest2.aspx?id=2″>ID
2</a> |  
   <a href=”OutputCachingTest2.aspx?id=3″>ID
3</a> | 
   <a href=”OutputCachingTest2.aspx?id=3&langid=1″>ID
3</a> 
</div>

  在页面中增加控件并且设置 EmployeeID.

  Web.config可以配置缓存相关的设置,

  控件缓存(Control Cache )

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