QT--HTTP协议的JSON的解析

蔚落 2022-12-21 09:24 199阅读 0赞

Qt提供了相应的类来处理Json，处理步骤如下：

1.通过json字符串构造一个json文本对象
        QJsonDocument::fromJson(json数据,错误信息);
    2.把json文本对象转换成json对象
        QJsonObject obj = doc.object();
    3.在json对象中根据key获取value
        obj.value("key").toString();
        obj.value("key").toArray();

用法实例如下：  
httpdownload.h

#ifndef HTTPDOWNLOAD_H
    #define HTTPDOWNLOAD_H
    
    #include <QMainWindow>
    #include <QtNetwork>
    #include <QNetworkAccessManager>
    #include <QNetworkRequest>
    #include <QNetworkReply>
    #include <QJsonDocument>
    #include <QJsonArray>
    #include <QJsonObject>
    #include <QJsonParseError>
    #include <QMessageBox>
    #include <QDebug>
    
    QT_BEGIN_NAMESPACE
    namespace Ui {  class HttpDownload; }
    QT_END_NAMESPACE
    
    class HttpDownload : public QMainWindow
    { 
        Q_OBJECT
    
    public:
        HttpDownload(QWidget *parent = nullptr);
        ~HttpDownload();
    
    private slots:
        void on_pushButton_clicked();
    
        void readdata_slot(QNetworkReply *reply);
    private:
        Ui::HttpDownload *ui;
    
        QNetworkAccessManager *manager;             //Http管理对象
    };
    #endif // HTTPDOWNLOAD_H

httpdownload.c

#include "httpdownload.h"
    #include "ui_httpdownload.h"
    
    HttpDownload::HttpDownload(QWidget *parent)
        : QMainWindow(parent)
        , ui(new Ui::HttpDownload)
    { 
        ui->setupUi(this);
        manager = new QNetworkAccessManager(this);
    
        //连接请求完成和读取数据的槽
        QObject::connect(manager,&QNetworkAccessManager::finished,this,&HttpDownload::readdata_slot);
    }
    
    HttpDownload::~HttpDownload()
    { 
        delete ui;
    }
    
    //发送请求
    void HttpDownload::on_pushButton_clicked()
    { 
        //获取url
        QUrl url(ui->lineEdit->text());
    
        //创建http请求
        QNetworkRequest request(url);
    
        //发送http请求 ----- GET
        manager->get(request);
    }
    
    //获取请求返回的数据
    void HttpDownload::readdata_slot(QNetworkReply *reply)
    { 
        QByteArray arr = reply->readAll();
        ui->textBrowser->setText(arr);
    
        //解析Json
        QJsonParseError error;
        QJsonDocument doc = QJsonDocument::fromJson(arr,&error);
    
        //判断json数据是否完整
        if(error.error!=QJsonParseError::NoError)
        { 
            //设置弹窗
            QMessageBox box;
            box.setText("Json数据错误!");
            box.setStandardButtons(QMessageBox::Ok);
            box.exec();
    
            return;
        }
    
        //将文本对象转换成json对象
        QJsonObject obj = doc.object();
    
        //在json对象中根据key获取value
        qDebug()<<obj.value("success").toString();
    
        //解析数组
        QJsonArray json_arr = obj.value("result").toArray();
        QJsonObject json_obj = json_arr.at(0).toObject();
    
        QString citynm = json_obj.value("citynm").toString();
        QString weather = json_obj.value("weather").toString();
        QString temperature = json_obj.value("temperature").toString();
    
        //显示
        ui->label->setText(citynm+":"+weather+" "+temperature);
    }

运行结果：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center]  
编译环境windows10,+QT5.12.0  
![在这里插入图片描述][20201115210256731.png_pic_center]  
[完整代码：https://download.csdn.net/download/weixin\_43793181/20335391][https_download.csdn.net_download_weixin_43793181_20335391]

编译时如果出现错误：qt.network.ssl: QSslSocket::connectToHostEncrypted: TLS initialization failed  
1.首先确定你选择打开工程的编译器是64位还是32位，确定方法如下（构建套件一栏）：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 1]  
2.去QtCreator的安装目录，搜索ssleay32.dll和libeay32.dll,**找到mingw730\_64路径下的文件**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 2]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 3]

3.然后把它们放到你生成的可执行文件目录，再次运行，该错误消失。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/fe022b5eaa084c358513737d059d1a6f.png
[20201115210256731.png_pic_center]: /images/20221120/ba4fbb15726941458d1f8e6c9890b079.png
[https_download.csdn.net_download_weixin_43793181_20335391]: https://download.csdn.net/download/weixin_43793181/20335391
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221120/4645d6a5e1eb42ae9ac293274e6a619f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221120/9f061f55a8ab4ea3a9ab15ad2120662e.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ_size_16_color_FFFFFF_t_70_pic_center 3]: https://img-blog.csdnimg.cn/20201115214235374.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzc5MzE4MQ==,size_16,color_FFFFFF,t_70#pic_center