Json序列化和结构体转换
使用nlohmann/json来实现, 该库内部提供了一些宏来实现了json和结构体的转换。
安装下载
git clone https://github.com/nlohmann/json.git mdkir build cd build cmake .. make make install
或者直接将仓库下的include的下nlohman目录拷贝到工程中.
引入工程
cmake_minimum_required(VERSION 3.0.0) project(SerializeJson VERSION 0.1.0) set(CMAKE_CXX_STANDARD 17) find_package(nlohmann_json 3.2.0 REQUIRED) add_executable(SerializeJson main.cpp) target_link_libraries(${PROJECT_NAME} nlohmann_json::nlohmann_json) set(CPACK_PROJECT_NAME ${PROJECT_NAME}) set(CPACK_PROJECT_VERSION ${PROJECT_VERSION})
在cpp中使用
#include <iostream> #include <vector> #include <map> #include <nlohmann/json.hpp> enum class Gender { THIRD = 0, MAN, WOMAN }; class Person { public: std::string name; int age = 18; Gender gender = Gender::MAN; }; class ClassRanking { public: std::vector<int> rank; // 年纪排名, 班级排名 std::map<std::string, double> courseGrade; // 科目和成绩 Person student; }; NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(Person, name, age, gender); NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(ClassRanking, rank, courseGrade, student); NLOHMANN_JSON_SERIALIZE_ENUM(Gender, {{Gender::THIRD, "THIRD"}, {Gender::MAN, "MAN"}, {Gender::WOMAN, "WOMAN"}, }); // intrusive class PersonIntrusive { public: std::string name; int age = 18; Gender gender = Gender::MAN; NLOHMANN_DEFINE_TYPE_INTRUSIVE(PersonIntrusive, name, age, gender); }; int main (int argc, char *argv[]) { // serialize Person person = {"Jeke", 20, Gender::MAN}; nlohmann::json j = person; std::cout << j.dump() << std::endl; // unserialize std::string buf = "{\"age\":20,\"name\":\"Jeke\", \"gender\":\"MAN\"}"; nlohmann::json k = nlohmann::json::parse(buf); Person fromJson = k; std::cout << "name: " << fromJson.name << ", age: " << fromJson.age << ", gender: " << int(fromJson.gender) << std::endl; ClassRanking rank; rank.rank = {10, 2}; rank.courseGrade = {{"Chinese", 105.5}, {"English", 115.0}, {"Math", 98}}; rank.student = person; nlohmann::json rankJ = rank; // std::cout << "rank: " << rankJ.dump(2) << std::endl; std::cout << "rank: " << rankJ.dump() << std::endl; std::string bufRank = "{\"rank\":[10,2],\"courseGrade\":{\"Chinese\":105.5,\"English\":115.0,\"Math\":98.0}," "\"student\":{\"age\":20,\"name\":\"Jeke\", \"gender\":\"MAN\"}}"; nlohmann::json rankK = nlohmann::json::parse(bufRank); ClassRanking fromJsonRank = rankK; std::cout << "course: [" << fromJsonRank.rank.at(0) << "," << fromJsonRank.rank.at(1) << "]" << std::endl; std::cout << "courseGrade: "; for (auto items : fromJsonRank.courseGrade) { std::cout << items.first << ": " << items.second; } std::cout << std::endl; std::cout << "name: " << fromJsonRank.student.name << ", age: " << fromJsonRank.student.age << ", gender: " << int(fromJsonRank.student.gender) << std::endl; return 0; }
