RFR [JDK8]: 7169894: JAXP Plugability Layer: using service loader

[Alan Bateman]

On 25/06/2012 08:38, Joe Wang wrote:
> Hi all,
>
> Thanks for all the comments!
>
> I've updated the patch for the following recommended changes:
> 1. ServiceConfigurationError instead of ConfigurationError
> 2. Use factory class, class.forName section removed
> 3. Use load method without specifying classloader
> 4. To be clear on how the process handles exceptions, I've updated 
> JavaDoc with the following:
>
>      * Uses the service-provider loading facilities, defined by the 
> {@link java.util.ServiceLoader} class, to attempt
>      * to locate and load an implementation of the service. In case 
> multiple providers exist, the first
>      * valid 3rd party provider should be returned; If there is no 
> valid 3rd party provider,
>      * the default implementation is returned if it is on the 
> classpath or installed as a module.
I think this is better, and I'm okay with your suggestion to deal with 
the code duplication issue separately.

On the above wording then I think term "3rd party provider" may provoke 
questions. How about "If there are providers other than the 
implementation specific default located, then the first provider that is 
not the default is instantiated and returned".

I'm not sure about catching and ignoring the ServiceConfigurationError 
(or "keep on trucking" as Paul termed it in one of the replies). The 
existing specification reads " Any Exception thrown during the 
instantiation process is wrapped as a <something>ConfigurationException" 
so this seems a significant change to me.

Would it be cleaner if the FactoryFinder.find methods were changed to:

static <T> T find(Class<T> c, String ...)

rather than using a raw type and returning Object? That would eliminate 
some of the casts in this case. I guess if the short term is to have a 
package-private copy of FactoryFinder in each package then it could be 
changed to return the specific type. Related to this is the changes 
increase the number of warnings by using ServiceLoader without a type 
parameter.

-Alan.