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Doubt with DI & JNDI

Mrinal Govind
Greenhorn

Joined: Jan 18, 2005
Posts: 3
The text below is from "EJB 3 in Action" book (section 5.2.3 Looking up resources and EJBs):

"using lookups instead of DI allows you to determine which resource to use dynamically at runtime instead of being constrained to using static configuration that cannot be changed programmatically."

Can someone kindly elaborate this in layman terms?
Davide Crudo
Ranch Hand

Joined: Sep 08, 2009
Posts: 62
"using lookups instead of DI allows you to determine which resource to use dynamically at runtime instead of being constrained to using static configuration that cannot be changed programmatically."


I think that the reason is that with DI you Hardcode the resource in the bean with for instance an annotation. On Runtime, you cannot assign a variable to the annotation, so, you need to stick with it...

With Lookups, you could theorically pass the reference as a variable, so that the resource reference can be decided at runtime...

for instance:

Using DI:



Using JNDI lookup:



Dave

SCJP, SCBCD
Mrinal Govind
Greenhorn

Joined: Jan 18, 2005
Posts: 3
Dave,

Thanks a lot for the reply!
What so say does makes sense.

Regards,
Mrinal

 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Doubt with DI & JNDI