java 脚本编程

java的脚本编程，在不用重新发版情况下就能修改业务实现，实用性还是挺不错的

现举一小例子
java 类：ScriptJava
public class ScriptJava {

    public static void main(String[] args) {
        ScriptEngine engine = new ScriptEngineManager().getEngineByName("javascript");
        Bindings bind = engine.createBindings();
        bind.put("factor", 1);
        engine.setBindings(bind, ScriptContext.ENGINE_SCOPE);
        Scanner input = new Scanner(System.in);
        while (input.hasNextInt()) {
            int first = input.nextInt();
            int sec = input.nextInt();
            System.out.println("参数：" + first + sec);
            try {
                engine.eval(new FileReader("C:/works_eprk/BetterJava151/src/com/java151/b01/model.js"));
                if (engine instanceof Invocable) {
                    Invocable in = (Invocable) engine;
                    Double result;
                    try {
                        result = (Double) in.invokeFunction("formula", first, sec);
                        System.out.println(result.intValue());
                    } catch (NoSuchMethodException e) {
                        e.printStackTrace();
                    }
                }
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (ScriptException e) {
                e.printStackTrace();
            }
        }
    }

}

js 文件：model.js
function formula (var1,var2) {
return var1 - var2 * factor;
}