What's the "principal" in Spring Security?
<p>I'm really new to Spring and Spring Security. I was reading about Spring Security and it came out the concept of <em>principal</em>, which should be the current logged user. But what if we have more than one current logged user? So, my question is, what exactly is then the principal in spring security?</p>

<p>I've read for example this tutorial:</p>

<blockquote>
  <p><a href="http://www.mkyong.com/spring-security/get-current-logged-in-username-in-spring-security/" rel="noreferrer">http://www.mkyong.com/spring-security/get-current-logged-in-username-in-spring-security/</a></p>
</blockquote>

<p>and they seem to take into account that there's just one current logged user, which isn't often the case.</p>

<p>How do I retrieve a specific user? And how do I differentiate between users that are doing requests?</p>