如何实现java Servlet，PHP CMS模板等自动编译？

I want to implement a small PHP template engine like smarty which would allow me to write my own php tag(if,for ..)

And now ,my problem is how to compile automatic when the template file was modified?

For example: Servlet . When we modified the servlet and waited for seconds ,the eclipse would tell you that the modified servlet class was recompiled !

Any help would be great!

You could check the modified date, between the cached compiled template, and the source file.

$cacheFileAge = @filemtime($this->cacheFile); //Get Time
foreach(array_merge(array($template),$this->snipFiles) as $f)
  if($cacheFileAge < filemtime($f)) //Compare every template to cache file
    return $this->parse(file_get_contents($template)); //If cache file older than one, re-compile it
debugLog("Using Cached file ({$this->cacheFile})");
include($this->cacheFile); //use cached file

This example was taken from another php template project HAMLE