In my previous post I was talking about how to create a service using Jdk service provider. In current post I am going to talk about how to implement your own Jsr223 Script Engine. And as you will see, script engines are a kind of Jdk service providers, so instead of creating your own set of interfaces, we are going to see how to implement a service provider of an already defined service.
Moreover we are going to see how we can convert a scripting language expression evaluator (in this case Spring EL) to be Jsr-223 compliant.
First of all for those who do not know what is Jsr-223 specification (or Java Scripting API), Jsr-223 is a scripting language independent framework for using script engines from Java code. Thanks of Jsr-223, we only use javax.script package instead of importing language specific classes.
For example using Spring EL scripting language, requires you import in your business class at least two Spring classes ExpressionParser and SpelExpressionParser, and if you want to use another scripting language, more specific vendor classes should be added, so your code is tied to script parser used.