Category: Snippets

Remove certain item or clear whole OmniFaces cache

Nick Russler

The Omnifaces o:cache Component is a useful Tool when trying to speed up you jsf powered website.

But in some situations you need to remove a certain item from the cache or you want to clear the whole cache, while there seems to be a way (Example 4) to remove single items by Key we couldn’t find a ‘official’ way to clear the whole cache.

 

Here is our Solution to the Problem:

public static boolean removeOmniCacheItem(String key) {    	
	Map<string , Object> applicationMap = FacesContext.getCurrentInstance().getExternalContext().getApplicationMap();
 
	if (applicationMap.containsKey(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME)) {
		synchronized (DefaultCacheProvider.class) {
			if (applicationMap.containsKey(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME)) {
				((Cache)applicationMap.get(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME)).remove(key);
				return true;
			}				
		}
	}
 
	return false;
}
 
public static boolean clearOmniCache() {    	
	Map</string><string , Object> applicationMap = FacesContext.getCurrentInstance().getExternalContext().getApplicationMap();
 
	if (applicationMap.containsKey(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME)) {
		synchronized (DefaultCacheProvider.class) {
			if (applicationMap.containsKey(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME)) {
				applicationMap.remove(DefaultCacheProvider.DEFAULT_CACHE_PARAM_NAME);
				return true;
			}				
		}
	}
 
	return false;
}
</string>

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Find File Snippet – Depth First And Breadth First Search

Ahmet Yüksektepe

Two usefull snippets, if you need to do a quick file search, here a recursive and a breadth first implementation (ignored the not-authorized-exception):
(took me only 2 mins, love .Net 🙂

Depth First Implementation:

static string[] FindFile_DepthFirst(string directoryName, string fileName)
{
   return Directory.GetFiles(directoryName, fileName, SearchOption.AllDirectories);
}

Breadth First Implementation:
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Update GUI Control From Non-GUI-Thread Without Marshalling

Ahmet Yüksektepe

In .Net when you want to update a GUI Control, for example a ListView, you have to execute your update code in the GUI Thread which controls your Form and its child GUI Objects. While you are in another Thread, you call the Invoke or BeginInvoke (for async.) method of your GUI Control for this purpose. You pass this method a delegate of your method, which contains your update code, and the GUI Thread invokes the method that is passed. Well the whole story is infact much more complicated and this article gives you a nice in-depth view on this topic:
WinForms UI Thread Invokes: An In-Depth Review of Invoke/BeginInvoke/InvokeRequred

 

This is how Microsoft wants us to manage our GUI stuff, Continue reading

How to get Main Window Handle of the last active window

Ahmet Yüksektepe

While developing a litte application for Windows 7 in C# i encountered the problem that i needed to focus the last window after i started my application. Althought my application was closing after execution immediately, focus was not recurring to the last window because i was starting my application from the windows taskbar. For fixing this side-effect, i needed to find out, which window was active before my programm was “born”. So i did some googling for finding out how to get the previously active window handle in windows 7. In almost every thread, it was recommended to “listen” to window activation changes, and save the previous handle in a variable or so. But in my case, i wanted to avoid, running the programm permanently, or run anything in the background..
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