Scripting in Java Example

Scripting in Java Example
Package javax.script 

Javax.script api provides the classes and interfaces for creating java script engines and executing java script inside java applications'

Example
Steps
· Instantiating Script engine manager instance with default constructor
· Creating script engine instance from Script engine manager
· Creating script context instance and add some values
· Execute Java Script
· Get the attribute values
· Print values

import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class ScriptingExample {
    public static void main(String[] args) {

        // Instantiating Script engine manager instance with default constructor
        ScriptEngineManager sem = new ScriptEngineManager();

        // Creating script engine instance from Script engine manager
        ScriptEngine engine = sem.getEngineByName("JavaScript");

        // Creating script context instance and add some values
        ScriptContext context = engine.getContext();

        context.setAttribute("a", 100, ScriptContext.ENGINE_SCOPE);
        context.setAttribute("b", 200, ScriptContext.ENGINE_SCOPE);

        // Execute Java Script
        try {
            engine.eval("print('Hello World!'); ");

            engine.eval("var total=a+b; ");

        } catch (ScriptException ex) {
            System.err.println(ex);
        }

        // Get the attribute values
        Double ans = (Double) context.getAttribute("total");
        // Print values
        System.out.println("Total value from script: " + ans);
    }
}

Output

Hello World!Total value from script: 300.0

 

References

                http://docs.oracle.com/javase/6/docs/api/javax/script/package-summary.html