Java Reference
In-Depth Information
public
public
Response
getResponse
() {...]
}
When JAX-RS sees that a
WebApplicationException
has been thrown by application code,
it catches the exception and calls its
getResponse()
method to obtain a
Response
to send
back to the client. If the application has initialized the
WebApplicationException
with a
status code or
Response
object, that code or
Response
will be used to create the actual
HTTP response. Otherwise, the
WebApplicationException
will return a status code of 500,
“Internal Server Error,” to the client.
For example, let's say we have a web service that allows clients to query for customers rep-
resented in XML:
@Path
(
"/customers"
)
public
public class
class
CustomerResource
CustomerResource
{
@GET
@Path
(
"{id}"
)
@Produces
(
"application/xml"
)
public
public
Customer
getCustomer
(
@PathParam
(
"id"
)
int
int
id
) {
Customer cust
=
findCustomer
(
id
);
iif
(
cust
==
null
null
) {
throw new
WebApplicationException
(
Response
.
Status
.
NOT_FOUND
);
}
return
return
cust
;
}
}
In this example, if we do not find a
Customer
instance with the given ID, we throw a
WebAp-
plicationException
that causes a 404, “Not Found,” status code to be sent back to the cli-
ent.
Exception Mapping
Many applications have to deal with a multitude of exceptions thrown from application code
and third-party frameworks. Relying on the underlying servlet container to handle the excep-
tion doesn't give us much flexibility. Catching and then wrapping all these exceptions within
WebApplicationException
would become quite tedious. Alternatively, you can implement
and register instances of
javax.ws.rs.ext.ExceptionMapper
. These objects know how to
map a thrown application exception to a
Response
object:
