Java解析字符串表达式

import  javax.script.*;
public  class  TestScript {
    public  static  void  main(String[] args)  throws  Exception {
        String str =  "(a >= 0 && a <= 5)" ;
        ScriptEngineManager manager =  new  ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName( "js" );
        engine.put( "a" , 4 );
        Object result = engine.eval(str);

        System.out.println( "结果类型:"  + result.getClass().getName() +  ",计算结果:"  + result);

    }
}