Asp.Net数据库缓存依赖
1.为数据库启用缓存依赖(您需要具有管理特权，或管理帐户和密码。)
在"Visual Studio 命令提示(2010(这里我用的是2010版本的,可以使用VS2005)"运行aspnet_regsql
(MSSQL 2000启用方式略有不同)
aspnet_regsql.exe -S Excel-lang -U sa -P sa -ed -d TestDB -et -t UserInfo
或者
aspnet_regsql -C "data source=Excel-lang;initial catalog=TestDB;user id=sa;password=sa" -ed -et -t "UserInfos"
注:1.数据库服务器名称为 Excel-lang 2.用户和密码为 sa sa 3.数据库和表分别为 TestDB UserInfo
运行完成后会在数据库下面产生一张表AspNet_SqlCacheTablesForChangeNotification和一个触发器
2.检查数据库是否启用监听服务
Select DataBasePropertyex('TestDB','IsBrokerEnabled')
或者
SELECT is_broker_enabled FROM sys.databases WHERE name = 'TestDB'
(1为已启用,0为未启用)
如果没有启用
使用语句ALTER DATABASE TestDB SET ENABLE_BROKER;启用监听服务
如果启用失败或者很长时间一直在执行请执行一下语句
ALTER DATABASE TestDB SET NEW_BROKER WITH ROLLBACK IMMEDIATE;
ALTER DATABASE TestDB SET ENABLE_BROKER;
3.配置WebConfig
<configuration>
<connectionStrings>节点下配置
<add name="TestDBConnectionString" connectionString="Data Source=EXCEL-LANG;Initial Catalog=TestDB;Persist Security Info=True;User ID=sa;Password=sa" providerName="System.Data.SqlClient" />
</connectionStrings>
<system.web> 节点下配置
<caching>
<sqlCacheDependency enabled="true" pollTime="1000">
<databases>
<add name="TestDB" connectionStringName="TestDBConnectionString"/>
</databases>
</sqlCacheDependency>
</caching>
各节点属性请参照MSDN相关文档
4.页面加载时执行以下代码,从数据库中获取数据并加入缓存中
List<UserInfo> list = DataCache.GetCache("UserInfoCache") as List<UserInfo>;
if (list == null)
{
System.Web.Caching.SqlCacheDependency dep = new System.Web.Caching.SqlCacheDependency("TestDB", "UserInfo");
list = userManger.GetUserLoginList();
onMoveBack = new CacheItemRemovedCallback(RemovedCallback);
DataCache.SetCache("UserInfoCache", list, dep, onMoveBack);
}
5.申明缓存失效后所执行的函数
CacheItemRemovedCallback onMoveBack;
private void RemovedCallback(String k, Object v, CacheItemRemovedReason r)
{
onMoveBack = new CacheItemRemovedCallback(RemovedCallback);
System.Web.Caching.SqlCacheDependency dep = new System.Web.Caching.SqlCacheDependency("TestDB", "UserInfo");
List<UserInfo> list = userManger.GetUserLoginList();//从数据库中获取数据
DataCache.SetCache("UserInfoCache", list, dep,onMoveBack);
}
6.DataCache类
using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Web.Caching;
public class DataCache
{
/// <summary>
/// 获取当前应用程序指定CacheKey的Cache值
/// </summary>
/// <param name="CacheKey"></param>
/// <returns></returns>
public static object GetCache(string CacheKey)
{
System.Web.Caching.Cache objCache = HttpRuntime.Cache;
return objCache[CacheKey];
}
/// <summary>
/// 设置当前应用程序指定CacheKey的Cache值
/// </summary>
/// <param name="CacheKey"></param>
/// <param name="objObject"></param>
public static void SetCache(string CacheKey, object objObject)
{
System.Web.Caching.Cache objCache = HttpRuntime.Cache;
objCache.Insert(CacheKey, objObject);
}
/// <summary>
/// 设置已缓存依赖的方式缓存数据
/// </summary>
/// <param name="CacheKey">键值</param>
/// <param name="objObject">缓存对象</param>
/// <param name="dep">缓存依赖项</param>
/// <param name="onMoveCallBack">缓存项移除是触发的回调函数</param>
public static void SetCache(string CacheKey, object objObject, System.Web.Caching.CacheDependency dep, CacheItemRemovedCallback onMoveCallBack)
{
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,
onMoveCallBack
);
}
}
7.执行步骤为从数据库查询数据→加入缓存(同时设置过期策略以及过期回调函数)→过期时→执行过期回调函数
RemovedCallback→重新查询数据并加入缓存.
缓存依赖是