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。

QNetworkAccessManager QNetworkRequest QNetworkReply

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
#include

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("");
    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！