Json文件是这样:
{
"first fruit":
{
"describe":"an apple",
"icon":"appleIcon",
"name":"apple"
},
"second fruit":
{
"describe":"an orange",
"icon":"orangeIcon",
"name":"orange"
},
"three fruit array":
[
"eat 0",
"eat 1",
"eat 2",
"eat 3",
"eat 4"
]
}
存放在本地磁盘。
利用QJson可以方便的进行解析。
QFile loadFile("D:\1.json");
if(!loadFile.open(QIODevice::ReadOnly))
{
qDebug() << "could't open projects json";
return;
}
QByteArray allData = loadFile.readAll();//第一步读取文件到BA
loadFile.close();
QJsonParseError json_error;
QJsonDocument jsonDoc(QJsonDocument::fromJson(allData, &json_error));//第二步将BA内容转为json文档
if(json_error.error != QJsonParseError::NoError)
{
qDebug() << "json error!";
return;
}
QJsonObject rootObj = jsonDoc.object();//第三步获取json文档对象
//输出所有key,这一步是非必须的,放最后的话,你可能读不到任何key
QStringList keys = rootObj.keys();//第四步获取json文档对象的所有keys
for(int i = 0; i < keys.size(); i++)
{
qDebug() << "key" << i << " is:" << keys.at(i);
}
//因为是预先定义好的JSON数据格式,所以这里可以这样读取
if(rootObj.contains("first fruit"))//第五步根据keys获取内容
{
QJsonObject subObj = rootObj.take("first fruit").toObject();
qDebug() << "describe is:" << subObj["describe"].toString();
qDebug() << "icon is:" << subObj["icon"].toString();
qDebug() << "name is:" << subObj["name"].toString();
}
if(rootObj.contains("second fruit"))
{
QJsonObject subObj = rootObj.take("second fruit").toObject();
qDebug() << "describe is:" << subObj.take("describe").toString();
qDebug() << "icon is:" << subObj.take("icon").toString();
qDebug() << "name is:" << subObj.take("name").toString();
}
if(rootObj.contains("three fruit array"))
{
QJsonArray subArray = rootObj.take("three fruit array").toArray();
for(int i = 0; i< subArray.size(); i++)
{
qDebug() << i<<" value is:" << subArray.at(i).toString();
}
}
需要包含的头文件:
#include <QJsonDocument>
#include <QJsonParseError>
#include <QFile>
#include <QJsonObject>
#include <QDebug>
#include <QJsonArray>
运行结果:
key 0 is: "first fruit"
key 1 is: "second fruit"
key 2 is: "three fruit array"
describe is: "an apple"
icon is: "appleIcon"
name is: "apple"
describe is: "an orange"
icon is: "orangeIcon"
name is: "orange"
0 value is: "eat 0"
1 value is: "eat 1"
2 value is: "eat 2"
3 value is: "eat 3"
4 value is: "eat 4"
以上转:https://blog.csdn.net/hp_cpp/article/details/80338116
PS:如何写json
QJsonObject roadJsonSubObject;
roadJsonSubObject.insert("IP", ui.lineEdit_5->text());
roadJsonSubObject.insert("PORT", ui.lineEdit_7->text());
QJsonDocument document;
document.setObject(roadJsonSubObject);
QByteArray ba = document.toJson(QJsonDocument::Compact);