Using Rhino and JSR-223 to read a JSON file

JSON, JSON, ​​ Jackson Jettison, . readFile JavaScript. , JSON.parse JavaScript eval .

JavaScript JSON, Java 7, - ( )...

public static void main(final String args[]) throws Exception {
    final ScriptEngineManager factory = new ScriptEngineManager();
    final ScriptEngine engine = factory.getEngineByName("js");
    Object val = null;
    Scanner s = null;
    try {
        s = new Scanner(new File("foo.json"));
        s.useDelimiter("\\Z");
        engine.getBindings(ScriptContext.GLOBAL_SCOPE).put("json", s.next());
    } finally {
        if (s != null) {
            s.close();
        }
    }
    // The default JavaScript engine in Java 6 does not have JSON.parse
    // but eval('(' + json + ')') would work
    val = engine.eval("JSON.parse(json)");

    // The default value is probably a JavaScript internal object and not very useful
    System.out.println(val.getClass() + " = " + val);
    // Java 7 uses Rhino 1.7R3 the objects will implement Map or List where appropriate
    // So in Java 7 we can turn this into something a little more useable
    // This is where Java 6 breaks down, in Java 6 you would have to use the 
    // sun.org.mozilla.javascript.internal classes to get any useful data
    System.out.println(convert(val));
}

@SuppressWarnings("unchecked")
public static Object convert(final Object val) {
    if (val instanceof Map) {
        final Map<String, Object> result = new HashMap<String, Object>();
        for (final Map.Entry<String, Object> entry: ((Map<String, Object>) val).entrySet()) {
            result.put(entry.getKey(), convert(entry.getValue()));
        }
        return result;
    } else if (val instanceof List) {
        final List<Object> result = new ArrayList<Object>();
        for (final Object item: ((List<Object>) val)) {
            result.add(convert(item));
        }
        return result;
    }
    if (val != null) {
        System.out.println(val.getClass() + " = " + val);
    }
    return val;
}

JavaScript, Java, , Rhino. readFile Rhino Shell, . Oracle , jrunscript .

, readFile Rhino JavaScript : Java Javascript Rhino?

public static void main(final String args[]) throws Exception {
    final ScriptEngineManager factory = new ScriptEngineManager();
    final ScriptEngine engine = factory.getEngineByName("js");
    engine.getBindings(ScriptContext.GLOBAL_SCOPE).put("utils", new Utils());
    engine.eval("for(var fn in utils) {\r\n" +
            "  if(typeof utils[fn] === 'function') {\r\n" +
            "    this[fn] = (function() {\r\n" +
            "       var method = utils[fn];\r\n" +
            "       return function() {\r\n" +
            "         return method.apply(utils,arguments);\r\n" +
            "       };\r\n" +
            "    })();\r\n" +
            "  }\r\n" +
            "}");
    engine.eval("println(readFile('foo.json'))");
}

static class Utils {
    public String readFile(final String fileName) throws FileNotFoundException {
        return readFile(fileName, null);
    }
    public String readFile(final String fileName, final String encoding) throws FileNotFoundException {
        Scanner s = null;
        try {
            s = new Scanner(new File(fileName), (encoding == null)? Charset.defaultCharset().name(): encoding);
            s.useDelimiter("\\Z");
            return s.next();
        } finally {
            if (s != null) {
                s.close();
            }
        }
    }
}