C++ qt 使用jsoncpp json

时间:2022-05-24 决战小树林人气:0

JsonCpp的使用

项目需要c++下使用json，我选择了JsonCpp，官网是：https://github.com/open-source-parsers/jsoncpp。
解压后使用python编译出两个h文件和一个cpp文件：

(电脑需要安装python自己百度安装，这里就不说了)

安装python后，打开windows下cmd窗口，进入到jsoncpp文件夹如图：

执行命令：python amalgamate.py 就会生成dist文件夹里面有 json.h json-forwards.h jsoncpp.cpp三个文件：如下

将三个文件加入到工程即可使用，我是要qt进行测试使用：

main.cpp如下

#include <iostream>
#include <fstream>
#include "dist/json/json.h"
using namespace std;
 
int main(int argc, char *argv[])
{
    // write
    Json::Value people1;
    people1["name"] = "Dione";
    people1["sex"] = "男";
    people1["age"] = 24;
    people1["note"] = "jsoncpp write test!";
 
    Json::Value people2;
    people2["name"] = "Hulis";
    people2["sex"] = "女";
    people2["age"] = 22;
    people2["note"] = "jsoncpp write test!";
 
    Json::Value peoples;
    peoples.append(people1);
    peoples.append(people2);
 
    Json::Value writeValue;
    writeValue["classname"] = "三年一班";
    writeValue["peoples"] = peoples;
 
 
    Json::FastWriter fwriter;
    std::string strf = fwriter.write(writeValue);
    std::ofstream ofsf("example_fast_writer.json");
    ofsf << strf;
    ofsf.close();
 
    Json::StyledWriter swriter;
    std::string strs = swriter.write(writeValue);
    std::ofstream ofss("example_styled_writer.json");
    ofss << strs;
    ofss.close();
 
    // read
    string strValue = "{\"key1\":\"111\",\"array\":[{\"key2\":\"222\"},{\"key2\":\"333\"},{\"key2\":\"444\"}]}";
    Json::Reader reader;
    Json::Value root;
    if (reader.parse(strValue, root))
    {
        std::string out = root["key1"].asString();
        qDebug()<<QString::fromStdString(out);
        Json::Value arrayObj = root["array"];
        for (int i=0; i<arrayObj.size(); i++)
        {
            out = arrayObj[i]["key2"].asString();
            qDebug()<<QString::fromStdString(out);
        }
    }
 
    std::ifstream ifs("example_fast_writer.json");
    if (reader.parse(ifs, root))
    {
        std::string out = root["classname"].asString();
        qDebug()<<QString::fromStdString(out);
        Json::Value peoples = root["peoples"];
        for (int i=0; i<peoples.size(); i++)
        {
            qDebug()<<QString::fromStdString(peoples[i]["name"].asString());
            qDebug()<<QString::fromStdString(peoples[i]["sex"].asString());
            qDebug()<<QString::fromStdString(peoples[i]["age"].asString());
            qDebug()<<QString::fromStdString(peoples[i]["note"].asString());
        }
    }
 
    return 0;
}

会生成两个json文件，一个是没有格式写入一个是有格式写入，如下：

Demo工程下载地址：点击此处下载

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