.net2.0缓存小例测试

缓存是.net2.0引入的一个新东西,借助SqlCacheDependency(存在于System.Web.Cacheing下)可以添加缓存项对数据库表或查询的依赖,这个东西用在sql2005下可以不用设置因为sql2005已经提供了缓存依赖的条件,用在sql2000下用有两种办法都可以实现:

一.要对数据库进行下命令操作

使用aspnet_regsql命令行工具,aspnet_regsql工具位于Windows\Microsoft.NET\Framework\[版本]文件夹中,如果要配置SqlCacheDependency，则需要以命令行的方式执行。例如:
aspnet_regsql -S localhost -E -d test -ed  //test为数据库名称
aspnet_regsql -S localhost -E -d test -t news -et  //test为数据库名字,news为表名

二.或者使用SqlCacheDependencyAdmin类

方法一:
在web.config文件<configuration>节中添加:

<connectionStrings>
  <add name="testConn" connectionString="server=.;database=test;uid=sa;pwd="/>
 </connectionStrings>

在接下来的<system.web>节中添加缓存策略如下:
<caching >
      <sqlCacheDependency  enabled="true" pollTime="600000">
        <databases>
          <add name="test" connectionStringName="testConn" pollTime="600000"/>
        </databases>
      </sqlCacheDependency>
    </caching>
注意:这里的<add>中的name是必须的,是要添加到设置集合中的SqlCacheDependencyDatabase对象的名称,此名称用作 @ OutputCache 指令上 SqlDependency 属性的一部分。pollTime:设置 SqlCacheDependency 轮询数据库表以查看是否发生更改的频率（以毫秒计算）。

在aspx页面放一个GridView,代码文件可以如下:
protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            string key = "TableCache";
            DataSet data = (DataSet)HttpRuntime.Cache[key];

            if (data == null)
            {
                data = GetDataSource();
                AggregateCacheDependency cd = TableDependency();
                HttpRuntime.Cache.Add(key, data, cd, DateTime.Now.AddHours(1), System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.High, null);
            }
            this.GridView1.DataSource = data;
            this.GridView1.DataBind();
        }
    }

    private AggregateCacheDependency TableDependency()
    {
        AggregateCacheDependency dependency = new AggregateCacheDependency();
        dependency.Add(new SqlCacheDependency("test", "news"));
        return dependency;
    }
    private DataSet GetDataSource()
    {
        DataSet ds = SqlHelper.ExecuteDataset(CommandType.StoredProcedure, "GetAllNews");
        return ds;
    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        this.GridView1.PageIndex = e.NewPageIndex;
        this.GridView1.DataSource = GetDataSource();
        this.GridView1.DataBind();
    }

方法二:使用SqlCacheDependencyAdmin类,web.config文件配置和方法一一样

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            string key = "TableCache";
            DataSet data = (DataSet)HttpRuntime.Cache[key];

            if (data == null)
            {
                data = GetDataSource();
                //启用指定数据库的更改通知
                SqlCacheDependencyAdmin.EnableNotifications(ConfigurationManager.ConnectionStrings["testConn"].ConnectionString);
                //连接到sqlserver数据库并为SqlCacheDependency更改通知准备数据库表
                SqlCacheDependencyAdmin.EnableTableForNotifications(ConfigurationManager.ConnectionStrings["testConn"].ConnectionString, "news");
                //指定缓存策略
                SqlCacheDependency scd = new SqlCacheDependency("test", "news");
                //插入缓存
                HttpRuntime.Cache.Insert(key, data, scd);
            }
            this.GridView1.DataSource = data;
            this.GridView1.DataBind();
        }
    }

    private DataSet GetDataSource()
    {
        DataSet ds = SqlHelper.ExecuteDataset(CommandType.StoredProcedure, "GetAllNews");
        return ds;
    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        this.GridView1.PageIndex = e.NewPageIndex;
        this.GridView1.DataSource = GetDataSource();
        this.GridView1.DataBind();
    }