Parsing JSON and Evaluating expressions from its fields

Question

I have a JSON document from which I have figured a way of parsing and extracting the values within it using the library of JSON-Path

I have to evaluate rules/expressions using the variables in the parsed JSON.

For example:

{maxAge:25, minAge:20, age:25}

• rule1 : $.maxAge-$.minAge>100 then send alert
• rule2 : $.age<18 then send alert

What libraries are available in Java for the same ?

Answer 1

Figured out a way, apparently, I don't need a JSON path. I can use javascript directly inside my code. so I've written rules in javascript

public static void main(String[] args) {
        ScriptEngineManager mgr = new ScriptEngineManager();
        ScriptEngine jsEngine = mgr.getEngineByName("JavaScript");
        String json = "{\"maxAge\":25, \"minAge\":20, \"age\":25}";
        String rule = "(x.maxAge)-(x.minAge) > 0;";

        jsEngine.put("x", json);

        try {
            jsEngine.eval("function test(abc){" + "var x=JSON.parse(abc);" + "return " + rule + "}");

            Invocable inv = (Invocable) jsEngine;
            boolean result = (Boolean) inv.invokeFunction("test", json);
            if (result) {
                System.out.println("Alert rule triggered");
            }

        } catch (ScriptException ex) {
            ex.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }

    }