用正则表达式简单解析JSON字符串

目前JSON格式数据使用很广泛，无论在C#和Java中都经常会用到。

解析JSON字符串，往往要依赖第三方库。

偶尔一个小功能，需引用第三方库来解析JSON有点得不偿失。

反而直接用正则进行匹配更为直接有效（个人观点，不喜勿喷）。

以下面JSON为例：

{"kpjh":"","fpdm":"051002550521","fphm":"43460571","fplxdm":"026","hjse":"0.00","kprq":"20220714133345","jshj":"155633.64","mw":"03-8408+>*5+<1>796>622-98<>2*736+6/360527166/9<>9420<-+*-**<82/9/01/+7650><*-+3","hjje":"155633.64","jym":"1629240248**833707375"}

需求：需解析出里面指定的字段值，如：fpdm字段。

实现：用正则表达式进行字段匹配：

表达式：String reg = "(?:"" + key + ""):"(?[^"]*?)""; key 为要匹配的字段名称。

原理：环视要匹配的字段，再将字段值命名捕获到val。

注意：默认匹配字符串中不含有"号才适用。

JAVA代码

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {

    public static void main(String[] args) throws Exception {
        String text = "{"kpjh":"","fpdm":"051002550521","fphm":"43460571","fplxdm":"026","hjse":"0.00","kprq":"20220714133345","jshj":"155633.64","mw":"03-8408+>*5+<1>796>622-98<>2*736+6/360527166/9<>9420<-+*-**<82/9/01/+7650><*-+3","hjje":"155633.64","jym":"1629240248**833707375"}";
        String key = "fpdm";//要匹配的字段
        String reg = "(?:"" + key + ""):"(?[^"]*?)"";//原理：环视要匹配的字段，再将字段值命名捕获到val
        Pattern pattern = Pattern.compile(reg);
        Matcher matcher = pattern.matcher(text);
        String value = "";
        while (matcher.find()) {
            value = matcher.group("val");
        }
        System.out.println("匹配:" + key + " = " + value);
    }
}

C#代码

using System;
using System.Text.RegularExpressions;

namespace ConsoleApp1
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            var text = "{"kpjh":"","fpdm":"051002550521","fphm":"43460571","fplxdm":"026","hjse":"0.00","kprq":"20220714133345","jshj":"155633.64","mw":"03-8408+>*5+<1>796>622-98<>2*736+6/360527166/9<>9420<-+*-**<82/9/01/+7650><*-+3","hjje":"155633.64","jym":"1629240248**833707375"}";
            var key = "fpdm"; //要匹配的字段
            var reg = "(?:"" + key + ""):"(?[^"]*?)""; //原理：环视要匹配的字段，再将字段值命名捕获到val
            var val = new Regex(reg).Match(text).Groups["val"].Value;
            Console.Write("匹配："+key + "= " + val);
        }
    }
}