System.Web.Caching 命名空间提供用于缓存服务器上常用数据的类。此命名空间包括 Cache 类，该类是一个字典，您可以在其中存储任意数据对象，如哈希表和数据集。它还为这些对象提供了失效功能，并为您提供了添加和移除这些对象的方法。您还可以添加依赖于其他文件或缓存项的对象，并在从 Cache对象中移除对象时执行回调以通知应用程序。
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<div style="margin:0px;padding:0px;line-height:21px;"><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"> 获取当前应用程序指定CacheKey的Cache对象值 <br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"></summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="CacheKey"></span><span style="margin:0px;padding:0px;color:#008000;">索引键值</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><returns></span><span style="margin:0px;padding:0px;color:#008000;">返回缓存对象</span><span style="margin:0px;padding:0px;color:#808080;"></returns></span><span style="margin:0px;padding:0px;color:#808080;"> </span><span style="margin:0px;padding:0px;color:#000000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">public</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">static</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">object</span><span style="margin:0px;padding:0px;color:#000000;"> GetCache(</span><span style="margin:0px;padding:0px;color:#0000ff;">string</span><span style="margin:0px;padding:0px;color:#000000;"> CacheKey)<br style="margin:0px;padding:0px;line-height:10px;" />{<br style="margin:0px;padding:0px;line-height:10px;" /> System.Web.Caching.Cache objCache </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> HttpRuntime.Cache;<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">return</span><span style="margin:0px;padding:0px;color:#000000;"> objCache[CacheKey];<br style="margin:0px;padding:0px;line-height:10px;" />}<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"> 设置当前应用程序指定CacheKey的Cache对象值<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"></summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="CacheKey"></span><span style="margin:0px;padding:0px;color:#008000;">索引键值</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="objObject"></span><span style="margin:0px;padding:0px;color:#008000;">缓存对象</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#000000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">public</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">static</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">void</span><span style="margin:0px;padding:0px;color:#000000;"> SetCache(</span><span style="margin:0px;padding:0px;color:#0000ff;">string</span><span style="margin:0px;padding:0px;color:#000000;"> CacheKey, </span><span style="margin:0px;padding:0px;color:#0000ff;">object</span><span style="margin:0px;padding:0px;color:#000000;"> objObject)<br style="margin:0px;padding:0px;line-height:10px;" />{<br style="margin:0px;padding:0px;line-height:10px;" /> System.Web.Caching.Cache objCache </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> HttpRuntime.Cache;<br style="margin:0px;padding:0px;line-height:10px;" /> objCache.Insert(CacheKey, objObject);<br style="margin:0px;padding:0px;line-height:10px;" />}<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"> 设置当前应用程序指定CacheKey的Cache对象值<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"></summary></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="CacheKey"></span><span style="margin:0px;padding:0px;color:#008000;">索引键值</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="objObject"></span><span style="margin:0px;padding:0px;color:#008000;">缓存对象</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="absoluteExpiration"></span><span style="margin:0px;padding:0px;color:#008000;">绝对过期时间</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#808080;">///</span><span style="margin:0px;padding:0px;color:#008000;"></span><span style="margin:0px;padding:0px;color:#808080;"><param name="slidingExpiration"></span><span style="margin:0px;padding:0px;color:#008000;">最后一次访问所插入对象时与该对象过期时之间的时间间隔</span><span style="margin:0px;padding:0px;color:#808080;"></param></span><span style="margin:0px;padding:0px;color:#808080;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">public</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">static</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">void</span><span style="margin:0px;padding:0px;color:#000000;"> SetCache(</span><span style="margin:0px;padding:0px;color:#0000ff;">string</span><span style="margin:0px;padding:0px;color:#000000;"> CacheKey, </span><span style="margin:0px;padding:0px;color:#0000ff;">object</span><span style="margin:0px;padding:0px;color:#000000;"> objObject, DateTime absoluteExpiration, TimeSpan slidingExpiration)<br style="margin:0px;padding:0px;line-height:10px;" />{<br style="margin:0px;padding:0px;line-height:10px;" /> System.Web.Caching.Cache objCache </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> HttpRuntime.Cache;<br style="margin:0px;padding:0px;line-height:10px;" /> objCache.Insert(CacheKey, objObject, </span><span style="margin:0px;padding:0px;color:#0000ff;">null</span><span style="margin:0px;padding:0px;color:#000000;">, absoluteExpiration, slidingExpiration);<br style="margin:0px;padding:0px;line-height:10px;" />} <br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">protected</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">void</span><span style="margin:0px;padding:0px;color:#000000;"> Page_Load(</span><span style="margin:0px;padding:0px;color:#0000ff;">object</span><span style="margin:0px;padding:0px;color:#000000;"> sender, EventArgs e)<br style="margin:0px;padding:0px;line-height:10px;" />{<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">string</span><span style="margin:0px;padding:0px;color:#000000;"> CacheKey </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#800000;">"</span><span style="margin:0px;padding:0px;color:#800000;">cachetest</span><span style="margin:0px;padding:0px;color:#800000;">"</span><span style="margin:0px;padding:0px;color:#000000;">;<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">object</span><span style="margin:0px;padding:0px;color:#000000;"> objModel </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> GetCache(CacheKey);</span><span style="margin:0px;padding:0px;color:#008000;">//</span><span style="margin:0px;padding:0px;color:#008000;">从缓存中获取</span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">if</span><span style="margin:0px;padding:0px;color:#000000;"> (objModel </span><span style="margin:0px;padding:0px;color:#000000;">==</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">null</span><span style="margin:0px;padding:0px;color:#000000;">)</span><span style="margin:0px;padding:0px;color:#008000;">//</span><span style="margin:0px;padding:0px;color:#008000;">缓存里没有</span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#000000;"> {<br style="margin:0px;padding:0px;line-height:10px;" /> objModel </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> DateTime.Now;</span><span style="margin:0px;padding:0px;color:#008000;">//</span><span style="margin:0px;padding:0px;color:#008000;">把当前时间进行缓存</span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">if</span><span style="margin:0px;padding:0px;color:#000000;"> (objModel </span><span style="margin:0px;padding:0px;color:#000000;">!=</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#0000ff;">null</span><span style="margin:0px;padding:0px;color:#000000;">)<br style="margin:0px;padding:0px;line-height:10px;" /> {<br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#0000ff;">int</span><span style="margin:0px;padding:0px;color:#000000;"> CacheTime </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"></span><span style="margin:0px;padding:0px;color:#800080;">30</span><span style="margin:0px;padding:0px;color:#000000;">;</span><span style="margin:0px;padding:0px;color:#008000;">//</span><span style="margin:0px;padding:0px;color:#008000;">缓存时间30秒</span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#000000;"> SetCache(CacheKey, objModel, DateTime.Now.AddSeconds(CacheTime), TimeSpan.Zero);</span><span style="margin:0px;padding:0px;color:#008000;">//</span><span style="margin:0px;padding:0px;color:#008000;">写入缓存</span><span style="margin:0px;padding:0px;color:#008000;"><br style="margin:0px;padding:0px;line-height:10px;" /></span><span style="margin:0px;padding:0px;color:#000000;"> }<br style="margin:0px;padding:0px;line-height:10px;" /> }<br style="margin:0px;padding:0px;line-height:10px;" /> Label1.Text </span><span style="margin:0px;padding:0px;color:#000000;">=</span><span style="margin:0px;padding:0px;color:#000000;"> objModel.ToString();<br style="margin:0px;padding:0px;line-height:10px;" />}</span></div> |
以上几种方法都很好的解决了数据缓存的问题，但由一个最大的问题是当数据发生变化了，而缓存里还是过期的数据，只有等缓存过期后才会重新获取最新的数据，这样的话，很多时候用户获取的数据都是和实际数据不一致的过期数据。这同样给用户造成了比较大的麻烦，怎么办呢？接着往下看。