Rhino和Java之间通过JSR223进行互操作：使用Javascript对象实例

Question

This is very similar to this other SO question about arrays .

If I evaluate:

y = {a: 1, b: 2, "momomomo": function() { return "hi"; }, zz: "wham"}

in a Javascript script instantiated via JSR223 (ScriptingEngine), I get a NativeObject of some sort (I see this in Eclipse's debugger) and have no idea how to access its properties. Furthermore I don't even know which .jar file, if any, I need to add to my build path to be able to work with the class in question, and if I find an approach that works in Rhino Javascript, it is useless for Jython.

Seems like JSR223 should have included language-agnostic access methods to ScriptingEngine to provide the ability to wrap a returned object as a List<Object> for arrays or a Map<String, Object> for associative arrays.

Any suggestions?

Answer 1

I too am trying to embed different scripting languages with more features than jsr223 or bsf. For that i have had to define my own interfaces and implement thse around each different scripting engine.

One feature i wanted was the ability to pass a Function (java interface with a single method) to my scripting engine and have it just work when passed parameters. Each of my embedded scripting engines has a layer where i wrap/unwrap from/to java values from the scripting environment.

I would suggest the best way to solve the problem is for your wrapper around the scripting engine to provide a getValue( String name ) and have it fix up javascript arrays convertoing them to java Lists. Naturally the setValue(String, Object) would check if the value is a List and convert it back to a js array and so on. Its tedious :()

Answer 2

Convert it to a java object and return it. You can then work with the java object as you would normally.

The following is an example conversion function

function convertToJava(o) {
    var rval;
    if (Array.isArray(o)) {
        rval = new java.util.ArrayList();
        for (var key in o) {
            rval.add(convertToJava(o[key]));
        }
    } 
    else if (typeof o === 'object') {
        rval = new java.util.HashMap();
        for (var key in o) {
            rval.put(key, convertToJava(o[key]));
        }
    }
    else if (typeof o === 'function') {
        // skip
    }
    else if (typeof o === 'undefined') {
        // skip
    }
    else {
        rval = o;
    }
    return rval;
}