看了兩天的Qt網絡編程，其實主要就是看了看QNetworkAccessManager、QNetworkRequest和QNetworkReply這三個類的主要內容。在之前，Qt網絡編程主要是使用QHttp等類，但是現在在幫助手冊中這些類已經標記為過時的，所以，現在用Qt編寫網絡程序最好還是使用上面的三個類，之前也說過，對于一個應用程序來說，一個QNetworkAccessManager已經足夠了。不知道你有沒有通過名字看出這三個類的聯系呢？這里再貼一下三個類的官方說明，加強印象，也有助于大家對照接下來的示例看。

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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

個人感覺三者關系可簡單理解如下：

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? ? ? ? ? ?接下來就看一個示例，其實主要內容還是Nokia給的示例，但是源程序有錯誤之處，我這里進行修改了，這里先貼一下效果：

? ? ? ? ?再來貼一下主要的代碼，代碼簡單，一看就懂，呵呵：

?

[cpp]?view plaincopy

#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

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