AspNetCore.Docs/aspnet/whitepapers/aspnet4/overview/samples/sample14.cs

39 lines
1.4 KiB
C#

private void btnGet_Click(object sender, EventArgs e)
{
//Obtain a reference to the default MemoryCache instance.
//Note that you can create multiple MemoryCache(s) inside
//of a single application.
ObjectCache cache = MemoryCache.Default;
//In this example the cache is storing the contents of a file string
fileContents = cache["filecontents"] as string;
//If the file contents are not currently in the cache, then
//the contents are read from disk and placed in the cache.
if (fileContents == null)
{
//A CacheItemPolicy object holds all the pieces of cache
//dependency and cache expiration metadata related to a single
//cache entry.
CacheItemPolicy policy = new CacheItemPolicy();
//Build up the information necessary to create a file dependency.
//In this case we just need the file path of the file on disk.
List filePaths = new List();
filePaths.Add("c:\\data.txt");
//In the new cache API, dependencies are called "change monitors".
//For this example we want the cache entry to be automatically expired
//if the contents on disk change. A HostFileChangeMonitor provides
//this functionality.
policy.ChangeMonitors.Add(new HostFileChangeMonitor(filePaths));
//Fetch the file's contents
fileContents = File.ReadAllText("c:\\data.txt");
//And then store the file's contents in the cache
cache.Set("filecontents", fileContents, policy);
}
MessageBox.Show(fileContents);
}