java 执行js的eval方法

public static void main(String[] arags){
        try{
            ScriptEngineManager manager = new ScriptEngineManager();
            ScriptEngine engine = manager.getEngineByName("JavaScript");
            StringBuffer script = new StringBuffer();
            script.append("var a = 0;");
//            script.append("obj.r = 0;");
//            script.append("obj.hello = function(name){print('hello, '+name);}");
            script.append("a = eval('1==1 && 1==1');");
            //执行这段script脚本
            engine.eval(script.toString());
            // javax.script.Invocable 是一个可选的接口
            // 检查你的script engine 接口是否已实现!
            // 注意：JavaScript engine实现了Invocable接口
            Invocable inv = (Invocable) engine;
            // 获取我们想调用那个方法所属的js对象
            Object obj = engine.get("a");
            System.out.println(obj);
        } catch (Exception ex){
            ex.printStackTrace();
        }
    }