JAVA执行字符串表达式 进行数值计算

package test;import java.io.*;import javax.script.ScriptEngine;import javax.script.ScriptEngineManager;public class Test2{        public static void main(String[] args) throws Exception        {                String expr = "x+y*10";                ScriptEngineManager manager = new ScriptEngineManager();                ScriptEngine engine = manager.getEngineByName("js");                engine.put("x", 10);                engine.put("y", 10);                Object result = engine.eval(expr);               System.out.println(result);        }}