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Posted to users@cxf.apache.org by Christian Balzer <ch...@gmail.com> on 2016/10/05 23:33:41 UTC

What is the "Type genericType" parameter in the JAX-RS ParamConverterProvider's getConverter() method for?

Hi all,

This is probably the wrong place, but...

Can anyone explain to me in plain simple English what the genericType
parameter below is good for, please?

public class FooHandler implements ParamConverterProvider {
    @Override
    public <T> ParamConverter<T> getConverter(final Class<T> rawType,
Type genericType, Annotation[] annotations) {

I'm afraid I don't quite understand the JavaDoc from
https://docs.oracle.com/javaee/7/api/javax/ws/rs/ext/ParamConverterProvider.html
- and I couldn't find an example anywhere...

From the docs:
>> genericType - the type of object to be converted. E.g. if an String value representing the injected request parameter is to be converted into a method parameter, this will be the formal type of the method parameter as returned by Class.getGenericParameterTypes. <<

From that, I would have expected that for this method signature:
> public Response foo(@MatrixParam("l") List<String> myList) {
genericType would be String?

As in:
>> if an String value ["abc"] representing the injected request parameter [";l", i.e. ";l=abc"] is to be converted into a method parameter [myList], this will be the formal type [<String>] of the method parameter [List<String>] as returned by Class.getGenericParameterTypes. <<

Am I close?

Kind regards,

Christian

Re: What is the "Type genericType" parameter in the JAX-RS ParamConverterProvider's getConverter() method for?

Posted by Sergey Beryozkin <sb...@gmail.com>.

Np, FYI there was a bug in CXF, fixed for 3.1.8-SNAPSHOT:
https://issues.apache.org/jira/browse/CXF-6992

Sergey
On 06/10/16 14:16, Christian Balzer wrote:
> Thanks.
>
> So, I suppose I could do (((ParameterizedType)
> genericType).getActualTypeArguments() to get hold of the actual
> Integer in your example, if I'm not mistaken. Useful to know for next
> time. :)
>
> Regards,
> Christian
>
> On Thu, Oct 6, 2016 at 1:32 PM, Sergey Beryozkin <sb...@gmail.com> wrote:
>> Hi Christian
>>
>>
>> If you have something like
>>
>> MyType<Integer>
>>
>> then the generic type will help the converter implementation to figure out
>> that MyType is parameterized by Integer.
>>
>> If you have List<MyType<Integer>> then as I noted earlier the List will be
>> created by the runtime while individual matrix/query etc properties will be
>> converted to MyType<Integer> by the converter
>>
>> Sergey
>>
>>
>> On 06/10/16 00:33, Christian Balzer wrote:
>>>
>>> Hi all,
>>>
>>> This is probably the wrong place, but...
>>>
>>> Can anyone explain to me in plain simple English what the genericType
>>> parameter below is good for, please?
>>>
>>> public class FooHandler implements ParamConverterProvider {
>>>     @Override
>>>     public <T> ParamConverter<T> getConverter(final Class<T> rawType,
>>> Type genericType, Annotation[] annotations) {
>>>
>>> I'm afraid I don't quite understand the JavaDoc from
>>>
>>> https://docs.oracle.com/javaee/7/api/javax/ws/rs/ext/ParamConverterProvider.html
>>> - and I couldn't find an example anywhere...
>>>
>>> From the docs:
>>>>>
>>>>> genericType - the type of object to be converted. E.g. if an String
>>>>> value representing the injected request parameter is to be converted into a
>>>>> method parameter, this will be the formal type of the method parameter as
>>>>> returned by Class.getGenericParameterTypes. <<
>>>
>>>
>>> From that, I would have expected that for this method signature:
>>>>
>>>> public Response foo(@MatrixParam("l") List<String> myList) {
>>>
>>> genericType would be String?
>>>
>>> As in:
>>>>>
>>>>> if an String value ["abc"] representing the injected request parameter
>>>>> [";l", i.e. ";l=abc"] is to be converted into a method parameter [myList],
>>>>> this will be the formal type [<String>] of the method parameter
>>>>> [List<String>] as returned by Class.getGenericParameterTypes. <<
>>>
>>>
>>> Am I close?
>>>
>>> Kind regards,
>>>
>>> Christian
>>>
>>
>>
>> --
>> Sergey Beryozkin
>>
>> Talend Community Coders
>> http://coders.talend.com/

Re: What is the "Type genericType" parameter in the JAX-RS ParamConverterProvider's getConverter() method for?

Posted by Christian Balzer <ch...@gmail.com>.

Thanks.

So, I suppose I could do (((ParameterizedType)
genericType).getActualTypeArguments() to get hold of the actual
Integer in your example, if I'm not mistaken. Useful to know for next
time. :)

Regards,
Christian

On Thu, Oct 6, 2016 at 1:32 PM, Sergey Beryozkin <sb...@gmail.com> wrote:
> Hi Christian
>
>
> If you have something like
>
> MyType<Integer>
>
> then the generic type will help the converter implementation to figure out
> that MyType is parameterized by Integer.
>
> If you have List<MyType<Integer>> then as I noted earlier the List will be
> created by the runtime while individual matrix/query etc properties will be
> converted to MyType<Integer> by the converter
>
> Sergey
>
>
> On 06/10/16 00:33, Christian Balzer wrote:
>>
>> Hi all,
>>
>> This is probably the wrong place, but...
>>
>> Can anyone explain to me in plain simple English what the genericType
>> parameter below is good for, please?
>>
>> public class FooHandler implements ParamConverterProvider {
>>     @Override
>>     public <T> ParamConverter<T> getConverter(final Class<T> rawType,
>> Type genericType, Annotation[] annotations) {
>>
>> I'm afraid I don't quite understand the JavaDoc from
>>
>> https://docs.oracle.com/javaee/7/api/javax/ws/rs/ext/ParamConverterProvider.html
>> - and I couldn't find an example anywhere...
>>
>> From the docs:
>>>>
>>>> genericType - the type of object to be converted. E.g. if an String
>>>> value representing the injected request parameter is to be converted into a
>>>> method parameter, this will be the formal type of the method parameter as
>>>> returned by Class.getGenericParameterTypes. <<
>>
>>
>> From that, I would have expected that for this method signature:
>>>
>>> public Response foo(@MatrixParam("l") List<String> myList) {
>>
>> genericType would be String?
>>
>> As in:
>>>>
>>>> if an String value ["abc"] representing the injected request parameter
>>>> [";l", i.e. ";l=abc"] is to be converted into a method parameter [myList],
>>>> this will be the formal type [<String>] of the method parameter
>>>> [List<String>] as returned by Class.getGenericParameterTypes. <<
>>
>>
>> Am I close?
>>
>> Kind regards,
>>
>> Christian
>>
>
>
> --
> Sergey Beryozkin
>
> Talend Community Coders
> http://coders.talend.com/

Re: What is the "Type genericType" parameter in the JAX-RS ParamConverterProvider's getConverter() method for?

Posted by Sergey Beryozkin <sb...@gmail.com>.

Hi Christian


If you have something like

MyType<Integer>

then the generic type will help the converter implementation to figure 
out that MyType is parameterized by Integer.

If you have List<MyType<Integer>> then as I noted earlier the List will 
be created by the runtime while individual matrix/query etc properties 
will be converted to MyType<Integer> by the converter

Sergey

On 06/10/16 00:33, Christian Balzer wrote:
> Hi all,
>
> This is probably the wrong place, but...
>
> Can anyone explain to me in plain simple English what the genericType
> parameter below is good for, please?
>
> public class FooHandler implements ParamConverterProvider {
>     @Override
>     public <T> ParamConverter<T> getConverter(final Class<T> rawType,
> Type genericType, Annotation[] annotations) {
>
> I'm afraid I don't quite understand the JavaDoc from
> https://docs.oracle.com/javaee/7/api/javax/ws/rs/ext/ParamConverterProvider.html
> - and I couldn't find an example anywhere...
>
> From the docs:
>>> genericType - the type of object to be converted. E.g. if an String value representing the injected request parameter is to be converted into a method parameter, this will be the formal type of the method parameter as returned by Class.getGenericParameterTypes. <<
>
> From that, I would have expected that for this method signature:
>> public Response foo(@MatrixParam("l") List<String> myList) {
> genericType would be String?
>
> As in:
>>> if an String value ["abc"] representing the injected request parameter [";l", i.e. ";l=abc"] is to be converted into a method parameter [myList], this will be the formal type [<String>] of the method parameter [List<String>] as returned by Class.getGenericParameterTypes. <<
>
> Am I close?
>
> Kind regards,
>
> Christian
>


-- 
Sergey Beryozkin

Talend Community Coders
http://coders.talend.com/