I really want to do is define the provider for self-defined media type,
let's say application/x-protobuf, so I need to provide the implementations
of MessageBodyReader or messageBodyWriter to make it work. This is the per
application/x-protobuf provider, right?
This provider should read subclasses of MessageLite from the input stream.
MessageLite is the super class of all protobuf generated entities. But the
subclasses are open-ended.
So I guess I have three options to implement the provider as following
class ProtobufReaderProvider implements MessageBodyReader<Object>
class ProtobufReaderProvider implements MessageBodyReader<MessageLite>
class ProtobufReaderProvider implements MessageBodyReader
At the runtime, I want to de-serialize a concrete class, say Message which
defined as
class Message implements MessageLite;
Then Message.class cannot applied to any of the required Class<T> type
parameter in the readFrom method argument list of the three possible
implementations.
Did I missed something? Please help!
2013/4/18 Tatu Saloranta <tsaloranta_at_gmail.com>
> No. Typically you do not implement MessageBodyReaders or -Writers
> yourself, but they are either provided by Jersey (or other JAX-RS
> implementations), or external providers. These are usually per-dataformat
> (JSON, XML etc) providers.
> It could be argued that type parameter for these types is useless... it
> really does not buy much anything, since JAX-RS dispatchers need dynamic
> handling and end up casting things anyway.
>
> -+ Tatu +-
>
>
> On Wed, Apr 17, 2013 at 9:00 PM, George Cao <matrix3456_at_gmail.com> wrote:
>
>> Hi All,
>> I am using Jersey framework 1.17 for my RESTful servces.
>>
>> But I got a question about the design of the MessageBodyReader interface.
>>
>> public interface MessageBodyReader<T> {
>> boolean isReadable(Class<?> type, Type genericType,
>> Annotation annotations[], MediaType mediaType);
>>
>> T readFrom(Class<T> type, Type genericType,
>> Annotation annotations[], MediaType mediaType,
>> MultivaluedMap<String, String> httpHeaders,
>> InputStream entityStream) throws IOException,
>> WebApplicationException;
>>
>> }
>>
>> Seems that we need write exactly one MessageBodyReader implementation per
>> Class because of the type parameter T of the readFrom method argument list,
>> right?
>>
>> The problem here is that Class<S> or Class<?> cannot assigned to
>> Class<T>, even though S is a subclass of T.
>>
>> So I am wondering how to write a MessageBodyReader that can read all the
>> classes that are subclasses of one specific class C instead write lots of
>> concrete implementations?
>>
>
>