qt - qt networkManager 获取

Question

我想下载在行编辑小部件中输入的 url。

我无法让它工作，有人可以给我一个简短的代码片段，可以将文件的值放入 QString 吗？

void imdb::on_imdbGetButton_clicked()
{

Qstring link1 = ui->lineEdit2->text();
// QString link1 is the url to be downloaded.
}

我已经添加了所需的头文件..

谢谢..

Answer 1

我猜您正在尝试通过http下载文件。这是你可以做的：

1. 在你 *.pro 文件中添加QT += network
2. 创建QNetworkAccessManager类的实例；
3. 通过QNetworkRequest对象提供您的文件 URL：manager->get(QNetworkRequest("file_url"));
4. 连接到QNetworkAccessManager的完成信号
5. 在完成的信号处理程序中读取 QNetworkReply 的内容并将其保存到本地文件。

下面是一个小例子。下载将在 MainForm 类的按钮单击开始：

主窗口.h：

#include <QMainWindow>
#include <QNetworkAccessManager>
#include <QDebug>
#include <QUrl>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QFile>
#include <QFileInfo>
#include <QPushButton>

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    QNetworkAccessManager* _manager;

private slots:
    void on_pushButton_clicked();
    void downloadFinished(QNetworkReply *reply);
};

主窗口.cpp：

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QPushButton* button = new QPushButton("Download", this);
    button->setGeometry(20, 20, 80, 30);
    connect(button, SIGNAL(clicked()), SLOT(on_pushButton_clicked()));

    _manager = new QNetworkAccessManager(this);
    connect(_manager, SIGNAL(finished(QNetworkReply*)), SLOT(downloadFinished(QNetworkReply*)));
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    QUrl url("http://pics.mtii.com/ClassPictures2011/MIA/E110227-PMIA3-JEAN/thumbnails/P2270448%20copy.jpg");
    _manager->get(QNetworkRequest(url));
}

void MainWindow::downloadFinished(QNetworkReply *reply)
{
    QUrl url = reply->url();
    if (reply->error())
    {
        qDebug() << "Download of " <<  url.toEncoded().constData()
                 << " failed: " << reply->errorString();
    }
    else
    {
        QString path = url.path();
        QString fileName = QFileInfo(path).fileName();
        if (fileName.isEmpty()) fileName = "download";

        QFile file(fileName);
        if (file.open(QIODevice::WriteOnly))
        {
            file.write(reply->readAll());
            file.close();
        }

        qDebug() << "Download of " <<  url.toEncoded().constData()
                 << " succeded saved to: " << fileName;
    }
}

希望这会有所帮助，问候