Java で JavaScript を実行する

package hello.javax.script;

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

public class HelloScriptEngine3 {

    public static void main(String[] args) {

        System.out.println("[Hello,JavaScript]");

        // Hello, JavaScript
        {
            // Get the JavaScript engine
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("JavaScript");

            // 実行する
            String script1 = "var msg=\"Hello, JavaScript\"; println(msg);";
            try {
                // JavaScript 組み込み関数 println で出力
                engine.eval(script1); // Hello, JavaScript
            } catch (ScriptException e) {
                e.printStackTrace();
            }
        }

        System.out.println("[Object]");
        // JSON
        {
            // Get the JavaScript engine
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("JavaScript");

            String script2 = "var o = {x:1,y:2}; println(o.x);";
            try {
                engine.eval(script2); // 1
            } catch (ScriptException e) {
                e.printStackTrace();
            }
        }

        System.out.println("[function]");
        // Function definition and call
        {
            // Get the JavaScript engine
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("JavaScript");
            // 関数の定義と変数への代入
            String script1 = "function f1(x,y){return x+y;} var b = f1(1,3);";
            try {
                engine.eval(script1);
                // 変数の取り出し
                System.out.println(engine.get("b")); // 4.0
            } catch (ScriptException e) {
                e.printStackTrace();
            }
        }

        System.out.println("[function2]");
        {
            // Get the JavaScript engine
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("JavaScript");
            // 関数の定義
            String script1 = "function myfunc(a,b){return a+b;}";
            try {
                engine.eval(script1);
            } catch (ScriptException e) {
                e.printStackTrace();
            }

            {
                String script2 = "b = myfunc(100,-30);";
                try {
                    engine.eval(script2);
                    System.out.println(engine.get("b")); // 70.0
                } catch (ScriptException e) {
                    e.printStackTrace();
                }
            }

        }
    }

}