internal static CacheDependency GetCacheDependency(VirtualPath virtualPath)
{
VirtualPathProvider vpathProvider = HostingEnvironment.VirtualPathProvider;
return(vpathProvider.GetCacheDependency(virtualPath,
new SingleObjectCollection(virtualPath.VirtualPathString), DateTime.MaxValue));
}
public virtual CacheDependency GetCacheDependency(string virtualPath, IEnumerable virtualPathDependencies, DateTime utcStart)
{
if (prev != null)
{
return(prev.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart));
}
return(null);
}
/*
* Asks the provider for a CacheDependency that will be invalidated if any of the
* input files become invalid.
* utcStart contains the time (UTC) at which the files were read. Any change to the file
* made after that time (even if the change is in the past) should invalidate the
* CacheDependency.
* If the provider doesn't support using a CacheDependency, it should return null,
* or simply not override GetCacheDependency (the base implementation returns null).
*/
public virtual CacheDependency GetCacheDependency(string virtualPath, IEnumerable virtualPathDependencies, DateTime utcStart)
{
// Delegate to the previous VirtualPathProvider, if any
if (_previous == null)
{
return(null);
}
return(_previous.GetCacheDependency(virtualPath, virtualPathDependencies, utcStart));
}
/// <summary>
/// 创建指定虚拟路径文件的缓存依赖项，当文件发生变化时可以清除缓存。
/// </summary>
/// <param name="provider">当前所使用的虚拟路径提供程序</param>
/// <param name="virtualPath">需要监视的文件虚拟路径</param>
/// <returns>监视路径的缓存依赖项</returns>
public static CacheDependency CreateCacheDependency( VirtualPathProvider provider, string virtualPath )
{
var now = DateTime.UtcNow;
return provider.GetCacheDependency( virtualPath, new[] { virtualPath }, now ) ?? new CacheDependency( HostingEnvironment.MapPath( virtualPath ) );
}