java实现数学表达式计算（采用后缀表达式）

java实现数学表达式计算（采用后缀表达式）

业务中需要根据业务模板自动计算业务数据，采用jsexpression计算性能很差，因此需要自己实现。

直接上代码

package com.dules.basic.utils;import java.math.BigDecimal;
import java.util.Objects;
import java.util.Stack;import com.longersoftware.logging.LogbackLogger;
import com.longersoftware.logging.LogbackLoggerFactory;public class ExpressionUtils {private static final LogbackLogger logger = Logger(ExpressionUtils.class);private static final char NEGATIVE = '~';private Stack<Character> cStack = new Stack<Character>();private Stack<Double> iStack = new Stack<Double>();public String eval(String expression) {String ret = "NA";try {double re = this.CharArray());BigDecimal b = new BigDecimal(re);re = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();ret = re + "";} catch (Exception e) {e.printStackTrace();("expression error.{}", expression);}return ret;}// 符号等级static int cLevel(char c) {switch (c) {case '(':return 0;case '+':return 2;case '-':return 2;case '*':case '/':return 3;}return 0;}// 对栈进行运算p