基于nlohmann的JSON文件的读取应用

1、JSON文件格式如下

{
    "Use_Sign": {
        "Up_Board": "0",
        "Divide_Board": "0",
        "Insert_Machine": "0",
        "Front_CCD": "0",
        "Wave_Soldering": "0",
        "Back_AOI": "0",
        "Glue_Machine": "0",
        "Scanner": "1",
        "Line_Number": "M703",
        "Scanner_Style": "1",
        "Com_Port":"COM4",
        "Baud_Rate":"9600"
    },
    "Up_Board_Info": {
        "Ip_Address": "127.0.0.1",
        "Port_Number": "502"
    },
    "Divide_Board_Info": {
        "Ip_Address": "10.56.20.254",
        "Port_Number": "60000"
    },
    "Insert_Machine_Info": [
        {
            "Ip_Address": "10.56.20.200",
            "Port_Number": "8081"
        },
        {
            "Ip_Address": "10.56.20.200",
            "Port_Number": "8082"
        },
        {
            "Ip_Address": "10.56.20.200",
            "Port_Number": "8083"
        }
    ],
    "Front_CCD_Info": {
        "Ip_Address": "10.56.20.200",
        "Port_Number": "8084"
    },
    "Wave_Soldering_Info": {
        "Ip_Address": "10.56.20.200",
        "Port_Number": "8085"
    },
    "Back_AOI_Info": {
        "Ip_Address": "10.56.20.200",
        "Port_Number": "8086"
    },
    "Scanner_Info": {
        "Ip_Address": "10.57.6.154",
        "Port_Number": "23"
    },
    "Glue_Machine_Info": {
        "Ip_Address": "10.56.20.200",
        "Port_Number": "8087"
    }
}

2、针对1中的JSON格式文件定义结构体及数据基本操作(Config.h)

#pragma once
#include <nlohmann/json.hpp>
#include <string>
#include <vector>
#include <iostream>
#include <fstream>
using namespace std;
using json = nlohmann::json;

//the info of device
struct DeviceInfo {
    std::string Ip_Address;
    std::string Port_Number;

    // 重载输出运算符，方便调试
    friend std::ostream& operator<<(std::ostream& os, const DeviceInfo& info) {
        return os << "IP: " << info.Ip_Address << ", Port: " << info.Port_Number;
    }
};

struct MachineConfig {
    struct {
        std::string Up_Board;
        std::string Divide_Board;
        std::string Insert_Machine;
        std::string Front_CCD;
        std::string Wave_Soldering;
        std::string Back_AOI;
        std::string Glue_Machine;
        std::string Scanner;
        std::string Line_Number;
        std::string Scanner_Style;
        std::string Com_Port;
        std::string Baud_Rate;
    } Use_Sign;

    DeviceInfo Up_Board_Info;
    DeviceInfo Divide_Board_Info;
    std::vector<DeviceInfo> Insert_Machine_Info;
    DeviceInfo Front_CCD_Info;
    DeviceInfo Wave_Soldering_Info;
    DeviceInfo Back_AOI_Info;
    DeviceInfo Glue_Machine_Info;
    DeviceInfo Scanner_Info;
};

// JSON反序列化
inline void from_json(const json& j, DeviceInfo& d) {
    j.at("Ip_Address").get_to(d.Ip_Address);
    j.at("Port_Number").get_to(d.Port_Number);
}

inline void from_json(const json& j, MachineConfig& config) {
    // 解析Use_Sign部分
    const auto& use_sign = j.at("Use_Sign");
    use_sign.at("Up_Board").get_to(config.Use_Sign.Up_Board);
    use_sign.at("Divide_Board").get_to(config.Use_Sign.Divide_Board);
    use_sign.at("Insert_Machine").get_to(config.Use_Sign.Insert_Machine);
    use_sign.at("Front_CCD").get_to(config.Use_Sign.Front_CCD);
    use_sign.at("Wave_Soldering").get_to(config.Use_Sign.Wave_Soldering);
    use_sign.at("Back_AOI").get_to(config.Use_Sign.Back_AOI);
    use_sign.at("Glue_Machine").get_to(config.Use_Sign.Glue_Machine);
    use_sign.at("Scanner").get_to(config.Use_Sign.Scanner);
    use_sign.at("Line_Number").get_to(config.Use_Sign.Line_Number);
    use_sign.at("Scanner_Style").get_to(config.Use_Sign.Scanner_Style);
    use_sign.at("Com_Port").get_to(config.Use_Sign.Com_Port);
    use_sign.at("Baud_Rate").get_to(config.Use_Sign.Baud_Rate);

    // 解析各设备信息
    j.at("Up_Board_Info").get_to(config.Up_Board_Info);
    j.at("Divide_Board_Info").get_to(config.Divide_Board_Info);
    j.at("Insert_Machine_Info").get_to(config.Insert_Machine_Info);
    j.at("Front_CCD_Info").get_to(config.Front_CCD_Info);
    j.at("Wave_Soldering_Info").get_to(config.Wave_Soldering_Info);
    j.at("Back_AOI_Info").get_to(config.Back_AOI_Info);
    j.at("Glue_Machine_Info").get_to(config.Glue_Machine_Info);
    j.at("Scanner_Info").get_to(config.Scanner_Info);
}

3、数据读取及打印测试

#include <iostream>
#include "ConfigInfo.h"

using namespace std;
static MachineConfig m_pConfigInfo;

static MachineConfig load_config(const std::string& filename){ 
    std::ifstream ifs(filename);
    if (!ifs.is_open()) {
        std::cout << "can not open the config file: " << filename << endl;
    }

    json j;
    ifs >> j;
    return j.get<MachineConfig>();
}


int main()
{
    m_pConfigInfo = load_config("..\\x64\\LamdaLearn\\Config.json");
    std::cout << m_pConfigInfo.Divide_Board_Info << std::endl;

    for(const auto& device:m_pConfigInfo.Insert_Machine_Info)
        std::cout << device << std::endl;
}