How to write custom function in Jxls version 3?

[fudewei1]

customize function in jxls2 version demo

 Map<String, Object> functionMap = new HashMap<>();
 functionMap.put("demo", new JexlCustomFunctionDemo());
 evaluator.getJexlEngine().setFunctions(functionMap);

class JexlCustomFunctionDemo{
    public Integer mySum(Integer x, Integer y){
        return x + y;
    }
}

how to customize in function in jxls3?Found relevant documents, but I can't understand them. Can you provide relevant examples? Thank you:

If you add a custom functions object to the data map you can now use builder.needsPublicContext(customFunctions) and implement NeedsPublicContext interface on your custom functions class to retrieve the PublicContext. Evaluations can be done using the PublicContext. source

[gastendonk]

It is not advisable to use the complicated function mechanism. Instead, just add an object to the data map that provides the function.

data.put("cf", new JexlCustomFunctionDemo());

In Excel cell: ${cf.mySum(1, 2)}

If you need access to PublicContext, see example