If you live entirely in EJB world, then perhaps your concerns are very much valid. EJB and DI and for that matter anything other than EJBs do not mix well together!
If you look into DI without EJB goggles, you can see tremendous benefit it can offer. I prefer constructor based DI over setter based DI. First benefit I have experienced, and this is the experience of others as well who have had serious implementation done, is that it changes the way one designs the application. It forces you to consider the right structure and dependencies and think patterns. Side effect is the inbuilt extensibility and flexibility it brings to the table. One ends up writing very concise, efficient and highly modular code. Of course a lot depends upon the DI container you choose (picocontainer is by far the lightest of them).
As regards to the thread safty issues, DI forces you to design for it right from the onset. EJB was designed for the mass programmers (read corporate programmers, better than VBs!) and that's why all that single threadedness and pooling. The vets for ages have always strived to write reentrant code. So largely I see this as an issue depending upon which camp you belong to - EJB or rest of the world!
Posted by: vijayphadke on March 17, 2005 at 10:37 AM
del.icio.us 
Digg 
DZone 
Furl 
Reddit
java.net RSS Feeds
