Java APIs for Nashorn - Scripting in Java: Integrating with Groovy and JavaScript - page 327

Listing 12-7 contains the Java program that performs the following steps:

• Loads the

point.js script file that will load the definition of the
Point constructor
Gets the reference of the

•

Point constructor by calling engine.

get("Point")
Creates two •

Point objects named p1 and p2 by calling the
newObject() method on the Point constructor
Invokes the •

callMember() method on p1 to invoke its distance()
method to compute the distance between p1 and p2

• Invokes the

callMember() method on p1 and p2 to get their string
representation by calling their toString() method declared in
the Point constructor

• Finally, prints the distance between the two points

Listing 12-7. Creating Nashorn Objects in Java Code

// CreateScriptObject.java
package com.jdojo.script;

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import jdk.nashorn.api.scripting.ScriptObjectMirror;

public class CreateScriptObject {
public static void main(String[] args) {
// Construct the script file path
String scriptFileName = "point.js";
Path scriptPath = Paths.get(scriptFileName);
// Make sure the script file exists. If not, print the full
// path of the script file and terminate the program.
if (! Files.exists(scriptPath) ) {
System.out.println(scriptPath.toAbsolutePath() +
" does not exist.");
return;
}
// Get the Nashorn script engine
ScriptEngineManager manager = new ScriptEngineManager();