Loading Property file only when it is changed

Guys i have created a properties file outside the jboss classpath

(I kept outside because i can change during run开发者_StackOverflow社区time and the values will be reflected).

I am loading this property file (like System.getProperty("jboss.base.dir.home")) everytime to do rmi lookup .I think that everytime loading the same file, eventhough it is not changed is pain.

I want ideas , how to detect the change in properties file and load only when there is a change.i thought of having the timestamp of lastmodified .kindly let me know your suggestions.

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You could reuse Apache commons to read the property file : http://commons.apache.org/configuration/userguide/howto_filebased.html#Automatic_Reloading

OR

You could do it programatillcay yourself. This would reimplementing the apache commons code - probably with far less testing and more error prone. If you insist on this approach here is that I think you can do :

1. Use a wrapper class on a Properties instance.
2. This wrapper class should (when initialized) load the properties file from the predefined location (probably configurable)
3. The wrapper, post init, should start a thread that would run forever and do this :
   • record the modified timestamp of the properties file recently read (see methods in File class)
   • sleep for a configurable time period
   • wake up and check the modified timestamp of the properties file
   • if there is a difference in the timestamps - reload the properties file into the Properties instance. Remember this must be done in isolation (i.e change the object when no ones accessing it).

HTH

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Perhaps you could do this with a naming convention. For example, if there are no changes the file would be named (whatever you name it now) for example:

foo.properties

But, on the other hand, if you wish to change it, you could name it something like:

foo.properties-changed

You could then programmatically look for the '-changed' file, load it, and then strip off the suffix.

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This solution was inspired by javamonkey79's answer and by the way hot deployment is handled in JBoss EAP 6.1.0. Instead of renaming the foo.properties file whenever I change it, I created an additional foo.updated file in the same directory. Whenever I change the settings in the foo.properties file, I rename foo.updated to foo.doUpdate.

In the singleton bean that loads the settings from the foo.properties file on startup, before I try to get a certain value from the bean, I first check if there is a foo.doUpdate file in the configuration directory. If so, I read the settings from the foo.properties file, and then delete foo.doUpdate and create a new file named foo.updated.