关于数据库缓存依赖项的使用

心已赠人 2021-12-24 06:17 202阅读 0赞

SqlCacheDependency基于表的缓存应用在sql2000,以及slq20005中实现的原

理多一样,多是在需要检测的表上建立触发器,并且Asp.net运行时通过轮询机制来检测表

数据是否更改.  
使用步骤  
首先保证数据库里有相应的基础结构,可以通过aspnet\_regsql来配置,  
–S 服务器名称 –U 登陆ID –P 密码 –d 数据库名称 –t 要追踪的数据表的名称 –et  
eg：aspnet\_regsql -S 192.168.14.250 -U sa -P 123456 -d AirTicket -t Plane -et  
或者通过代码来建立基本结构  
SqlCacheDependencyAdmin.EnableNotifications(string connStr);  
SqlCacheDependencyAdmin.EnableTableForNotifications(string connstr, string\[\] tables);  
效果一样的

演示代码asp.net

=========基类==========

using System;  
using System.Collections.Generic;  
using System.Text;  
using System.Web.Caching;

namespace Wapdm.Utility.CacheDependency  
\{  
public abstract class SqlTableCacheDependencyBase:ICacheDependency  
\{  
protected AggregateCacheDependency \_dependency = new AggregateCacheDependency();

protected SqlTableCacheDependencyBase(string cacheDatabaseName, string tableName)  
\{  
\_dependency.Add(new SqlCacheDependency(cacheDatabaseName, tableName));  
\}

protected SqlTableCacheDependencyBase(string cacheDatabaseName, string\[\] tableNameList)  
\{  
foreach (string tableName in tableNameList)  
\{  
if (tableName != null && tableName.Length > 0)  
\{  
\_dependency.Add(new SqlCacheDependency(cacheDatabaseName, tableName));  
\}  
\}  
\}

public AggregateCacheDependency GetDependency() \{  
return \_dependency;  
\}  
\}  
\}

=========子类===========

using System;  
using System.Collections.Generic;  
using System.Text;

using System.Configuration;

namespace Wapdm.Utility.CacheDependency  
\{  
public class AirportNameTable : SqlTableCacheDependencyBase  
\{  
public AirportNameTable() : base(ConfigurationSettings.AppSettings\["CacheDataBase"\], new string\[\]\{ "AirPort", "Service\_City", "ForeignArea" \}) \{ \}  
\}  
\}

===========使用类=================================

using System;  
using System.Collections.Generic;  
using System.Text;  
using System.Web.Caching;  
using System.Web;  
using System.Data;

namespace Wapdm.Utility.Caches  
\{  
public class CacheManager  
\{  
readonly static string \_airportName = "AirportName";

public static string GetAirportName(string airCode)  
\{  
string key = airCode;  
string paramValue = string.Empty;  
if (HttpContext.Current.Cache\[key\] == null)  
\{  
if (HttpContext.Current.Cache\[\_airportName\] == null)  
\{  
HttpContext.Current.Cache.Insert(\_airportName,  
Wapdm.Utility.Dal.DataOperation.GetAllAirportName(),  
new Wapdm.Utility.CacheDependency.AirportNameTable().GetDependency());  
\}  
DataSet ds = (DataSet)HttpContext.Current.Cache\[\_airportName\];  
paramValue = Wapdm.Utility.Dal.DataOperation.GetAirportNameFromCache(key, ds.Tables\[0\]);  
HttpContext.Current.Cache.Insert(key, paramValue, new Wapdm.Utility.CacheDependency.AirportNameTable().GetDependency());  
\}  
paramValue = HttpContext.Current.Cache\[key\].ToString();  
return paramValue;  
\}  
\}  
\}

============调用====================

string airPortName = CacheManager.GetAirportName(destinationairpor);

最后,基于表的数据库缓存必须在web.config文件中有如下配置  
<system.web>  
.....  
<caching>  
<sqlCacheDependency enabled="true" pollTime="10000">  
<databases>  
<add name="CacheTest" connectionStringName="SQL2005CacheTest" pollTime="10000"/>  
</databases>  
</sqlCacheDependency>  
</caching>  
</system.web>  
pollTime为论询时间,建议不要少于1分钟,或更长,不然建议不要使用此类缓存.  
name="CacheTest",中的CacheTest,作为SqlCacheDependency(dbEntryName,table)构造函数参数dbEntryName,的传递值.这点要注意下.

转载于:https://www.cnblogs.com/gudubuku/archive/2008/08/26/1276704.html