boost库的编译不做赘述，这里用的版本是1.69.0，其他版本应该差不多

boost官网：https://www.boost.org/

0.前言

今天要整的JSON是这样的

{ "description": "this is a JSON test", "version": "100", "list": { "listkey1": "listvalue1", "listkey2": "listvalue2", "listkey3": "listvalue3" }, "words": [ "apple", "banana", "cat" ]}

首先先新建一个vs的工程，设置include路径和lib路径

额外添加的lib为\boost\1.69.0\stage64\lib\libboost_system-vc141-mt-gd-x64-1_69.lib

在头文件中添加

#include <boost/property_tree/ptree.hpp>#include <boost/property_tree/json_parser.hpp>

使用ptree来完成JSON的读写操作

1、写JSON字符串

1.0、如何将ptree转换成字符串输出到屏幕

使用stringstream

 std::stringstream ss; boost::property_tree::write_json(ss, pt); std::string strContent = ss.str(); 

1.1、添加简单值

　　 // root boost::property_tree::ptree root; // add simple value root.put(std::string("description"), std::string("this is a JSON test")); root.put(std::string("version"), 100);

1.2、添加一组对象

 // add a list of objs boost::property_tree::ptree ptObjs; ptObjs.put(std::string("listkey1"), std::string("listvalue1")); ptObjs.put(std::string("listkey2"), std::string("listvalue2")); ptObjs.put(std::string("listkey3"), std::string("listvalue3")); root.add_child(std::string("list"), ptObjs);

1.3、添加一组值

 // add a list of values boost::property_tree::ptree ptValItem1, ptValItem2, ptValItem3, ptVals; ptValItem1.put_value(std::string("apple")); ptVals.push_back(std::make_pair("", ptValItem1)); ptValItem2.put_value(std::string("banana")); ptVals.push_back(std::make_pair("", ptValItem2)); ptValItem3.put_value(std::string("cat")); ptVals.push_back(std::make_pair("", ptValItem3)); root.add_child(std::string("words"), ptVals);

1.4、输出到屏幕

先通过1.0写一个输出的function

void ptreePrint(boost::property_tree::ptree pt, std::string ptName, std::string descritpion){ std::stringstream ss; boost::property_tree::write_json(ss, pt); std::string strContent = ss.str(); std::cout << descritpion << std::endl << ptName << " : " << strContent << std::endl << "--------------------------------------\n";}

然后将每步产生的ptree输出

2.读JSON字符串

2.1 读简单值

 // read simple value std::string description = pt.get<std::string>("description"); int version = pt.get<int>("version");

2.2 读一组对象

 // read list of objs std::cout << std::endl << "read list of objs " << std::endl; for (auto ptItem : pt.get_child("list")) { std::string key = ptItem.first; std::string val = ptItem.second.data(); std::cout << "key:\t" << key << "\tvalue:\t" << val << std::endl; }

2.3 读一组值

 // read list of values  std::cout << std::endl << "read list of values" << std::endl << "words: "; for (auto ptItem : pt.get_child("words")) { std::cout << ptItem.second.data() << " "; }

2.4 输出到屏幕

3.完整代码

#include "pch.h"#include <iostream>#include <boost/property_tree/ptree.hpp>#include <boost/property_tree/json_parser.hpp>void readTest(boost::property_tree::ptree pt){ std::cout << __func__ << std::endl; // read simple value std::string description = pt.get<std::string>("description"); int version = pt.get<int>("version"); std::cout << "description : " << description << std::endl << "version : " << version << std::endl; // read list of objs std::cout << std::endl << "read list of objs " << std::endl; for (auto ptItem : pt.get_child("list")) { std::string key = ptItem.first; std::string val = ptItem.second.data(); std::cout << "key:\t" << key << "\tvalue:\t" << val << std::endl; } // read list of values  std::cout << std::endl << "read list of values" << std::endl << "words: "; for (auto ptItem : pt.get_child("words")) { std::cout << ptItem.second.data() << " "; }}void ptreePrint(boost::property_tree::ptree pt, std::string ptName, std::string descritpion){ std::stringstream ss; boost::property_tree::write_json(ss, pt); std::string strContent = ss.str(); std::cout << descritpion << std::endl << ptName << " : " << strContent << std::endl << "--------------------------------------\n";}void JSONtest(){ // root boost::property_tree::ptree root; // add simple value root.put(std::string("description"), std::string("this is a JSON test")); root.put(std::string("version"), 100); ptreePrint(root, std::string("root"), "add simple value"); // add a list of objs boost::property_tree::ptree ptObjs; ptObjs.put(std::string("listkey1"), std::string("listvalue1")); ptObjs.put(std::string("listkey2"), std::string("listvalue2")); ptObjs.put(std::string("listkey3"), std::string("listvalue3")); root.add_child(std::string("list"), ptObjs); ptreePrint(root, std::string("root"), "add a list of objs"); // add a list of values boost::property_tree::ptree ptValItem1, ptValItem2, ptValItem3, ptVals; ptValItem1.put_value(std::string("apple")); ptVals.push_back(std::make_pair("", ptValItem1)); ptValItem2.put_value(std::string("banana")); ptVals.push_back(std::make_pair("", ptValItem2)); ptValItem3.put_value(std::string("cat")); ptVals.push_back(std::make_pair("", ptValItem3)); root.add_child(std::string("words"), ptVals); ptreePrint(ptVals, std::string("ptVals"), ""); ptreePrint(root, std::string("root"), "add a list of values"); readTest(root);}int main(){ JSONtest();}