Qt网络编程之实例一GET方式
看了两天的Qt网络编程,其实主要就是看了看QNetworkAccessManager、QNetworkRequest和QNetworkReply这三个类的主要内容。在之前,Qt网络编程主要是使用QHttp等类,但是现在在帮助手册中这些类已经标记为过时的,所以,现在用Qt编写网络程序最好还是使用上面的三个类,之前也说过,对于一个应用程序来说,一个QNetworkAccessManager已经足够了。不知道你有没有通过名字看出这三个类的联系呢?这里再贴一下三个类的官方说明,加强印象,也有助于大家对照接下来的示例看。
Allows the application to send network requests and receive replie Holds a request to be sent with QNetworkAccessManager Contains the data and headers for a request sent with QNetworkAccessManager |
个人感觉三者关系可简单理解如下:
接下来就看一个示例,其实主要内容还是Nokia给的示例,但是源程序有错误之处,我这里进行修改了,这里先贴一下效果:
再来贴一下主要的代码,代码简单,一看就懂,呵呵:
- #include "mainwindow.h"
- #include "ui_mainwindow.h"
- #include <QNetworkReply>
- #include <QNetworkRequest>
- MainWindow::MainWindow(QWidget *parent) :
- QMainWindow(parent),
- ui(new Ui::MainWindow)
- {
- ui->setupUi(this);
- nam = new QNetworkAccessManager(this);
- QObject::connect(nam, SIGNAL(finished(QNetworkReply*)),
- this, SLOT(finishedSlot(QNetworkReply*)));
- }
- MainWindow::~MainWindow()
- {
- delete ui;
- }
- void MainWindow::on_pushButton_clicked()
- {
- QUrl url("http://www.hust.edu.cn/");
- QNetworkReply* reply = nam->get(QNetworkRequest(url));
- // NOTE: Store QNetworkReply pointer (maybe into caller).
- // When this HTTP request is finished you will receive this same
- // QNetworkReply as response parameter.
- // By the QNetworkReply pointer you can identify request and response.
- }
- void MainWindow::finishedSlot(QNetworkReply *reply)
- {
- #if 1
- // Reading attributes of the reply
- // e.g. the HTTP status code
- QVariant statusCodeV =
- reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
- // Or the target URL if it was a redirect:
- QVariant redirectionTargetUrl =
- reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
- // see CS001432 on how to handle this
- // no error received?
- if (reply->error() == QNetworkReply::NoError)
- {
- // read data from QNetworkReply here
- // Example 1: Creating QImage from the reply
- //QImageReader imageReader(reply);
- //QImage pic = imageReader.read();
- // Example 2: Reading bytes form the reply
- QByteArray bytes = reply->readAll(); // bytes
- //QString string(bytes); // string
- QString string = QString::fromUtf8(bytes);
- ui->textBrowser->setText(string);
- }
- // Some http error received
- else
- {
- // handle errors here
- }
- // We receive ownership of the reply object
- // and therefore need to handle deletion.
- reply->deleteLater();
- #endif
- }
好了,今天就到了