Looking into java service provider interface (SPI). Learning by example.

I took a look at the service provider interface in java. This is a needed interface to build simple services using easy building blocks to extend and improve programs or libraries. We will create one example and also look into some tools that use this interface already.
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Outro music: Sanaas Scylla
#java #service #spi

[@roman_mf]

Hello Daniel, thank you for refresher, such a short and sweet video. Are SPIs used primarily for compile-time extensions or runtime extensions? If I recompile a classfile of a plugin and ask ServiceLoader to load it again, will it load the updated classfile, or do I need exert additional effort to unload the previous version from memory?

[@DanielPersson]

Hi Roman To my knowledge, it's more of a runtime extension, and you should be able to switch out functions on the fly. I'm not sure if there are any recommendations to unload the class before loading a new one, but I really hope the garbage collector handles that issue. Currently, I only use it to load classes that extend common functionality and pack them in at compile time; I'm not switching in runtime. I hope this helps. Thank you for watching my videos. Best regards Daniel

[@marko-pololo]

Thank you for the video! very interesting! I saw a project with SPI and didn’t even know what it was, now it’s a little clearer! Sorry for my English)

[@БажанКозаченко]

It was a good example. Thank you for teaching java service provider interface.

[@hellosagar]

Thank you so much for the explanation

[@SarveshBhatnagar1214]

Well taught! Thanks....

[@yaroslavsoltys4846]

thank you for the great explanation!

[@Aragorn.Strider]

I hoped to find the Java9 version of this, but this Java6 version is a nice introduction, I learned something new, thanks

[@DanielPersson]

Hi Aragorn. Thank you for watching my videos. I did not know that the interface had changed in newer versions of java. I need to look into this; perhaps there is a better solution. The more you know :) Best regards Daniel

[@olafkliemt1145]

very nice - thanks !

[@GK-rl5du]

Hi Daniel, in the video you have mentioned for the serviceLoader to detect classes we have to mention the fully qualified class names under META-INF directory. I am wondering how does twelwemonkeys implementation is discovered wthout it?

[@DanielPersson]

Hi Goutham. I explain this after 6:30 in the video. We look into the jar file and see that they have added this file. So the service loader will look in the service files for all jar files and compile a list of optional formats that you could handle. Thank you for watching my videos. I hope this helps. Best regards Daniel

[@GK-rl5du]

@@DanielPersson Thanks for the reply.. I thought you were showing the META-INF directory of the actual project and not the library. My bad I was totally confused.

[@LeandroCoutinho]

Very nice Daniel! So then some jar can hijack interfaces?! Oo If you could do a video about Java Annotation Processor it would be great *-*

[@DanielPersson]

Hi Leandro Thank you for watching my videos. Yes, if there is an interface available you may extend with other implementations. I'll look into JAP and see if I can create a video about it. Best regards Daniel