JEP是java数学解析器的一个开源工具，解析并计算与数学运算相关的字符串的一个类库，是java数学解析器的一个开源工具,提供第三方的jar包只要将jar包放到lib目录下即可使用

简单示例：

import com.singularsys.jep.Jep;
import com.singularsys.jep.JepException;

public class SimpleExample {
    public static void main(String[] args) {
        Jep jep = new Jep();
        //一个数学表达式
        String exp = "((a+b)*(c+b))/(c+a)/b";
        //给变量赋值
        jep.addVariable("a", 10);
        jep.addVariable("b", 10);
        jep.addVariable("c", 10);
 
       try {
           //执行
           jep.parse(exp);
           Object result = jep.evaluate();
           System.out.println("计算结果： " + result);
        } catch (JepException e) {
            System.out.println("An error occured: " + e.getMessage());
        }
    }
}

具体更复杂的操作可以参看下载的zip中\doc\html\index.html

Jep is a Java library for parsing and evaluating mathematical expressions. With this package you can allow your users to enter an arbitrary formula as a string, and instantly evaluate it. Jep supports user defined variables, constants, and functions. A number of common mathematical functions and constants are included.
参考资料：http://www.singularsys.com/jep/doc/html/index.html