exception og dao

Umiddelbart (jeg har ikke checket koden) lyder det da som om at du har ret.

Der er ikke meget encapsulation hvis den kaldende kode catcher implementation
specific unchecked exceptions.

Umiddelbart virker det mest logisk enten at catche og throw en checked
exception nede i dao laget eller at catche alle runtime exceptions i den
kaldende kode.

Men der er mange forskellige opfattelser af hvordan exceptions skal bruges.

Bare fordi noget er publiceret i JavaWorld behøver koden ikke være god. Heller
ikke selvom "best practice" nævnes en snes gange i teksten.

Men du kunne vel skrive til forfatteren og spørge ham, hvorfor han har lavet
det på den måde.

Ok rart at høre at jeg ikke er helt forkert på den.
Tror jeg vil tage dit råd og skrive til ham.

Du må godt smide et svar, tak for hjælpen.

ok

Her er svaret fra ham der har lavet det:

Simon,

This is a good question and the answer is not short :)

Spring uses a different way to handle excpetion. Spring likes runtime exception, which does not force you to catch it. Whether or not to use Runtime exception or checked exception, there're a lot of discussions.

DAO helps you to isolate the data access logic,Hibernate vs. JDBC, Oracle vs. MySQL, etc. You are right, if you want to achieve a clear isolation between integration and business logic tier, u'd better define a whole bunch of data access exceptions and catch all exception in the intergration tier and rethrow as the new data access exception. However, sometimes, u realize for most application, it's pretty much a catch and rethrow and it's not doing any actual work.

The integration tier and business logic tier are tightly coupled, and sometimes they are refered as the middle tier. So, it's really up to you whether or not to make the clear seperation.

The answer - ideally, u should create data access exception and make the clear seperation. In the real world, maybe not. As long as you modulize your application, once the implementation change, there're only a minimum components need to be changed, it should be good enough.

Hopefully, it answers your question!

cheers,

Derek

Det betyder vist løst oversat: "Vi fandt det for ubetydeligt til at vi gad bruge tid på det".