ASP.NET Cache缓存的使用 (转载）

CacheDependencyfileDepends=newCacheDependency(Server.MapPath("Northwind.xml"));

Cache.Insert("GridViewDataSet",dsGrid,fileDepends);

此例为通过Northiwind.xml文件依赖出来缓存的用法：

2.2其他缓存项依赖：

string[]fileDependsArray={Server.MapPath("Northwind.xml")};

string[]cacheDependsArray={"Depend0","Depend1","Depend2"};

CacheDependencycacheDepends=newCacheDependency(fileDependsArray,cacheDependsArray);

Cache.Insert("GridViewDataSet",dsGrid,cacheDepends);

此例设置了Northwind.xml文件依赖和Depend0,depend1,Depend2缓存项

其中Depend0,depend1,Depend2为另外三个缓存。

如果不需要文件依赖可以设置为NULL。

2.3过期时间设定：

AbsoluteExpiration可以设置缓存的绝对过期时间，如：

Cache.Insert("GridViewDataSet",dsGrid,null,DateTime.Now.AddMinutes(30),Cache.NoSlidingExpiration);

缓存会在添加起30分钟后过期。

NoSlidingExpiration可以设置相对过期时间,如果缓存在NoSlidingExpiration设定的时间内没有被访问，缓存过期，如果在这段时间内有访问，则缓存过期时间将会重置为原始值，如NoSlidingExpiration=20

在20分钟内如果没有被访问，缓存过期，如果每次19分钟访问缓存，缓存将永远不会过期。

Cache.Insert("DataGridDataSet",dsGrid,null,Cache.NoAbsoluteExpiration,TimeSpan.FromSeconds(30));

3.优先级：

Priority属性值和意义：

usingSystem;

usingSystem.Data;

usingSystem.Configuration;

usingSystem.Web;

usingSystem.Web.Security;

usingSystem.Web.UI;

usingSystem.Web.UI.WebControls;

usingSystem.Web.UI.WebControls.WebParts;

usingSystem.Web.UI.HtmlControls;

usingSystem.Web.Caching;//necessaryforCacheDependency

usingSystem.Xml;//necessaryforXmlstuff

publicpartialclass_Default:System.Web.UI.Page

{

publicstaticCacheItemRemovedCallbackonRemove=null;

protectedvoidPage_Load(objectsender,EventArgse)

{

CreateGridView();

}

privatevoidCreateGridView()

{

DataSetdsGrid;

dsGrid=(DataSet)Cache["GridViewDataSet"];

onRemove=newCacheItemRemovedCallback(this.RemovedCallback);

if(dsGrid==null)

{

dsGrid=GetDataSet();

string[]fileDependsArray={Server.MapPath("Northwind.xml")};

string[]cacheDependsArray={"Depend0","Depend1","Depend2"};

CacheDependencycacheDepends=newCacheDependency

(fileDependsArray,cacheDependsArray);

Cache.Insert("GridViewDataSet",dsGrid,cacheDepends,

DateTime.Now.AddSeconds(10),

Cache.NoSlidingExpiration,

CacheItemPriority.Default,

onRemove);

lblMessage.Text="DatafromXMLfile.";

}

else

{

lblMessage.Text="Datafromcache.";

}

gv.DataSource=dsGrid.Tables[0];

gv.DataBind();

}

privateDataSetGetDataSet()

{

DataSetdsData=newDataSet();

XmlDataDocumentdoc=newXmlDataDocument();

doc.DataSet.ReadXml(Server.MapPath("Northwind.xml"));

dsData=doc.DataSet;

returndsData;

}

publicvoidRemovedCallback(stringcacheKey,

ObjectcacheObject,

CacheItemRemovedReasonreasonToRemove)

{

WriteFile("Cacheremovedforfollowingreason:"+

reasonToRemove.ToString());

}

privatevoidWriteFile(stringstrText)

{

System.IO.StreamWriterwriter=newSystem.IO.StreamWriter(

@"C:"test.txt",true);

stringstr;

str=DateTime.Now.ToString()+""+strText;

writer.WriteLine(str);

writer.Close();

}

protectedvoidbtnClear_Click(objectsender,EventArgse)

{

Cache.Remove("GridViewDataSet");

CreateGridView();

}

protectedvoidbtnInit_Click(objectsender,EventArgse)

{

//Initializecachestodependon.

Cache["Depend0"]="Thisisthefirstdependency.";

Cache["Depend1"]="Thisisthe2nddependency.";

Cache["Depend2"]="Thisisthe3rddependency.";

}

protectedvoidbtnKey0_Click(objectsender,EventArgse)

{

Cache["Depend0"]="Thisisachangedfirstdependency.";

}

}