no :-) Allow me to provide an example. This class : MoSKitoWebUIContext.java ( https://github.com/anotheria/moskito/blob/master/moskito-webui/src/main/java/net/anotheria/moskito/webui/MoSKitoWebUIContext.java ) Is a ThreadLocal that is used to store some information, for example HttpSession. In the beginning of the processing I am calling MoSKitoWebUIContext.getCallContextAndReset(); //that initializes the context and than MoSKitoWebUIContext .getCallContext().setCurrentSession(HttpSession currentSession);
from this time on the link to current session is stored in the ThreadLocal variable, and whereever in the call I need it, I can simply call MoSKitoWebUIContext .getCallContext().getCurrentSession() and obtain it, without explicitly passing it through call trees. This allows me to pass parameters from a very beginning of the processing to the very end of the processing (or just everywhere) without passing them around and having them in each and every method. Another popular example would be to store the Locale the user is in for i18n. HTH Leon P.S. of course you need to clean up the thread locals at the end of processing (at least in theory) and so on. On Tue, Sep 2, 2014 at 10:22 PM, Leo Donahue <donahu...@gmail.com> wrote: > On Tue, Sep 2, 2014 at 3:00 PM, Leon Rosenberg <rosenberg.l...@gmail.com> > wrote: > > > From practical point of view ThreadLocal is a huge hashmap directly in > the > > ThreadClass where you can store a map of variables. > > Something like Thread.Map<ThreadId, Map<String, Object>>, in which you > can > > access variables that are 'attached' logically to the current Thread. > > In practice its a nice way to pass information through layers of code > > without adding it explicitly as parameter to every function on the way. > > regards > > Leon > > > > At some point in the web application, a ThreadLocal is instantiated and its > properties are set and then retrieved in a Filter. Am I on track here? > > How is that different or more helpful than instantiating any other POJO > with property setters? > > A POJO will be instantiated on every servlet request whereas the > ThreadLocal is only created once? >
