您可能希望将用户界面和控制器（业务逻辑）分离到单独的类中。
的身体main()实例化 ui 和控制器并连接它们。每 5 秒获取新结果的计时器。计时器可以卷入Controller，我也将其单独展示为向现有类添加功能而不修改它的示例。
main.cpp
// https://github.com/KubaO/stackoverflown/tree/master/questions/into-mainwin-39643510
#include "mainwindow.h"
#include "controller.h"
int main(int argc, char *argv[])
{
QApplication app{argc, argv};
MainWindow ui;
Controller ctl;
QTimer timer;
timer.start(5*1000);
QObject::connect(&timer, &QTimer::timeout, &ctl, &Controller::get);
QObject::connect(&ctl, &Controller::busy, &ui, [&]{ ui.setState(MainWindow::Loading); });
QObject::connect(&ui, &MainWindow::request, &ctl, &Controller::get);
QObject::connect(&ctl, &Controller::error, &ui, [&]{ ui.setState(MainWindow::Error); });
QObject::connect(&ctl, &Controller::values, &ui, &MainWindow::setFields);
ui.show();
return app.exec();
}
控制器对用户界面一无所知，只负责处理请求。它发出一个busy每次开始处理请求时都会发出信号。
如果您想为多个活动请求提供更好的反馈，busy仅当没有待处理的请求并且添加了新请求时才需要发出信号，并且idle当最后一个请求完成并且没有更多待处理的请求时，将发出信号。
控制器.h
#ifndef CONTROLLER_H
#define CONTROLLER_H
#include <QtNetwork>
class Controller : public QObject {
Q_OBJECT
QNetworkAccessManager manager{this};
QNetworkRequest request;
Q_SLOT void onReply(QNetworkReply *);
public:
explicit Controller(QObject * parent = nullptr);
Q_SLOT void get();
Q_SIGNAL void busy();
Q_SIGNAL void error(const QString &);
Q_SIGNAL void values(const QString & name, const QString & gender, const QString & region);
};
#endif // CONTROLLER_H
控制器.cpp
#include "controller.h"
Controller::Controller(QObject *parent) : QObject(parent)
{
QUrlQuery query;
query.addQueryItem("amount", "1");
query.addQueryItem("region", "United States");
QUrl url("http://uinames.com/api/");
url.setQuery(query);
request = QNetworkRequest(url);
connect(&manager, &QNetworkAccessManager::finished, this, &Controller::onReply);
}
void Controller::onReply(QNetworkReply * reply) {
if (reply->error() != QNetworkReply::NoError) {
emit error(reply->errorString());
manager.clearAccessCache();
} else {
//parse the reply JSON and display result in the UI
auto jsonObject = QJsonDocument::fromJson(reply->readAll()).object();
auto fullName = jsonObject["name"].toString();
fullName.append(" ");
fullName.append(jsonObject["surname"].toString());
emit values(fullName, jsonObject["gender"].toString(), jsonObject["region"].toString());
}
reply->deleteLater();
}
void Controller::get() {
emit busy();
manager.get(request);
}
用户界面不知道任何业务逻辑，它提供了一个足以供业务逻辑使用它的 API。它可以处于以下三种状态之一：Normal结果可见的状态，Loading显示忙碌反馈的状态，以及Error显示错误信息的状态。这setFields槽将状态返回到Normal.
主窗口.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QtWidgets>
class MainWindow : public QWidget {
Q_OBJECT
QFormLayout layout{this};
QLineEdit lineEditName;
QLineEdit lineEditGender;
QLineEdit lineEditRegion;
QPushButton button{"Get Name"};
QLineEdit * edits[3] = {&lineEditName, &lineEditGender, &lineEditRegion};
public:
enum State { Normal, Loading, Error };
explicit MainWindow(QWidget * parent = nullptr);
Q_SLOT void setFields(const QString & name, const QString & gender, const QString & region);
Q_SLOT void setState(State);
Q_SIGNAL void request();
};
#endif // MAINWINDOW_H
主窗口.cpp
#include "mainwindow.h"
MainWindow::MainWindow(QWidget *parent) : QWidget(parent)
{
for(auto edit : edits) edit->setReadOnly(true);
layout.addRow("Name:", &lineEditName);
layout.addRow("Gender:", &lineEditGender);
layout.addRow("Region:", &lineEditRegion);
layout.addRow(&button);
connect(&button, &QPushButton::clicked, this, &MainWindow::request);
}
void MainWindow::setFields(const QString & name, const QString & gender, const QString & region) {
setState(Normal);
lineEditName.setText(name);
lineEditGender.setText(gender);
lineEditRegion.setText(region);
}
void MainWindow::setState(MainWindow::State state) {
if (state == Normal) {
for (auto edit : edits) edit->setEnabled(true);
button.setEnabled(true);
}
else if (state == Loading) {
for (auto edit : edits) edit->setEnabled(false);
button.setEnabled(false);
}
else if (state == Error) {
for (auto edit : edits) edit->setText("Error...");
button.setEnabled(true);
}
}
