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();
				}
			}

		}
	}

}