摘要：
1:缓存依赖的类别xmlversion=“1.0”encoding=“utf-8”？
文件,数据表,数据行,一段时间,控件,查询字符串等
2:缓存项之间的依赖
protected void Button3_Click(object sender, EventArgs e)
{
// create item A and item B string itemA = "ItemA"; string itemB = "ItemB"; Cache.Insert("ItemA", itemA, null, DateTime.Now.AddMinutes(10), TimeSpan.Zero, CacheItemPriority.Default, MyItemRemovedCallBack); Cache.Insert("ItemB", itemB, null, DateTime.Now.AddMinutes(10), TimeSpan.Zero, CacheItemPriority.Default, MyItemRemovedCallBack);
}private void MyItemRemovedCallBack(string key, object value, CacheItemRemovedReason reason){ // remove the item from the cache if (key == "ItemA" ) Cache.Remove("ItemB"); else if (key.Equals == "ItemB") Cache.Remove("ItemB");}Key:缓存集合中唯一确认一项的键
Value:保存在缓存中的值
Reason:是"CacheItemRemovedReason"的一个枚举.说明缓存项被移出的原因
我们也可以手动移出缓存
Cache.Remove("ItemA");<?xml version="1.0" encoding="utf-8"?><MenuItems> <MenuItem> <Text>Home</Text> </MenuItem> <MenuItem> <Text>About us</Text> </MenuItem> <MenuItem> <Text>Contact us</Text> </MenuItem> <MenuItem> <Text>Help</Text> </MenuItem> <MenuItem> <Text>Feature</Text> </MenuItem></MenuItems> string menuPath = "MyFiles/Menu.xml"; string folderName = "MyFiles/"; DataSet ds = null; if (Cache["Menu"] == null) { ds = new DataSet(); ds.ReadXml(Server.MapPath(menuPath)); // menu is created Cache.Insert("Menu", ds, new System.Web.Caching.CacheDependency( Server.MapPath(menuPath)),DateTime.Now.AddMinutes(60), TimeSpan.Zero, System.Web.Caching.CacheItemPriority.Default, new System.Web.Caching.CacheItemRemovedCallback( CacheItemRemovedCallBack)); DisplayCacheCreationTime("Object was not in the cache and created at:", DateTime.Now.ToLongTimeString()); } else { // menu is created from the cache DisplayCacheCreationTime("Object was in the cache",String.Empty); }4:数据库中的缓存依赖
<connectionStrings> <add name="ConnectionString" connectionString="Server=localhost;Database=School;Trusted_Connection=true"/></connectionStrings><system.web> <caching> <sqlCacheDependency pollTime="10000" enabled="true" > <databases> <add connectionStringName="ConnectionString" name="School"/> </databases> </sqlCacheDependency> </caching></caching> if (Cache["Users"] == null) { // Create the cache dependency SqlCacheDependency dep = new SqlCacheDependency("School", "Users"); string connectionString = ConfigurationManager.ConnectionStrings[ "ConnectionString"].ConnectionString; SqlConnection myConnection = new SqlConnection(connectionString); SqlDataAdapter ad = new SqlDataAdapter("SELECT FirstName, LastName " + "FROM Users", myConnection); DataSet ds = new DataSet(); ad.Fill(ds); // put in the cache object Cache.Insert("Users", ds, dep); } gvUsers.DataSource = Cache["Users"] as DataSet; gvUsers.DataBind();这部分代码适用于sql2000,在sql2005下没有这么麻烦.回头我们再讨论sql2005下的缓存.