package com.ruoyi.common.utils;
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import org.apache.commons.jexl3.*;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.regex.Matcher;
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import java.util.regex.Pattern;
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/**
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* @author mitao
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* @date 2024/3/27
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*/
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public class CalculateUtil {
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public static Map<String,Integer> getFieldsAndValue(String rule) {
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// 正则表达式模式，匹配形如 "fieldName:value" 的字符串
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Pattern pattern = Pattern.compile("\\b(\\w+)_(\\d+)\\b");
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Matcher matcher = pattern.matcher(rule);
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Map<String, Integer> map = new HashMap<>();
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// 循环匹配并输出字段名和值
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while (matcher.find()) {
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String fieldName = matcher.group(1);
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int value = Integer.parseInt(matcher.group(2));
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map.put(fieldName+"_"+value, value);
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}
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return map;
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}
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public static double calculate(String expression,Map<String,Object> value) {
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expression = formatExpression(expression);
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// 创建 JEXL 引擎
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JexlEngine jexl = new JexlBuilder().create();
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// 创建表达式对象
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JexlExpression exp = jexl.createExpression(expression);
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// 创建上下文
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JexlContext context = new MapContext();
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for (Map.Entry<String, Object> stringObjectEntry : value.entrySet()) {
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context.set(stringObjectEntry.getKey(),stringObjectEntry.getValue());
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}
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// 执行计算
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Object result = exp.evaluate(context);
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// 输出结果
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System.out.println("Result: " + result);
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return Double.parseDouble(result.toString());
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}
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public static String formatExpression(String expression) {
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return expression
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.replaceAll("×", "*")
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.replaceAll("÷", "/")
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.replaceAll("（", "(")
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.replaceAll("）", ")")
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.replaceAll("＋","+")
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.replaceAll("－", "-");
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}
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}
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