QT HTTP 通讯 使用方法

 //////////////grabthread.h////////////////////
 #ifndef GRABTHREAD_H
 #define GRABTHREAD_H

 #include <QThread>
 class QNetworkAccessManager;
 #include <QNetworkReply>

 class GrabThread : public QThread
 {
     Q_OBJECT
 public:
     explicit GrabThread(QObject *parent = 0);
     void run();
     void saveToFile(QString&);

     bool runrun;

 signals:

 public slots:
     void slot_httpFinished();
     void slot_httpError(QNetworkReply::NetworkError);

 private:
     QNetworkAccessManager* qnam;
     QNetworkReply* reply;
     QString query_word;
     bool is_init;
 };

 #endif // GRABTHREAD_H



 //////////////grabthread.cpp////////////////////
 #include <QtNetwork/QNetworkAccessManager>
 #include <QtNetwork/QNetworkReply>
 #include <QtNetwork/QNetworkRequest>
 #include <QEventLoop>

 GrabThread::GrabThread(QObject *parent) :
     QThread(parent),
     is_init(true)
 {
 }

 void GrabThread::run()
 {
     if (is_init)
     {
         qnam = new QNetworkAccessManager();
         is_init = false;
     }
     while(runrun)
     {
         startQuery("");
     }
 }

 void GrabThread::startQuery(QString redirect_url)
 {
     QNetworkRequest request;
     QString url;
     // 如果是重定向请求， 则直接指向位置， 否则拼字符串
     if (redirect_url.length() != 0)
     {
         url = redirect_url;
     }else
     {
         url = "http://www.nuihq.com/" + query_word;
     }
     // 设定url
     request.setUrl(QUrl(url));
     // 设定请求头
     request.setRawHeader("Host", "www.nuihq.com");
     request.setRawHeader("User-Agent", "Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1");
     request.setRawHeader("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
     request.setRawHeader("Accept-Language", "zh-cn,zh;q=0.5");
     // TODO:使用gzip
     request.setRawHeader("Accept-Encoding", "deflate");
     request.setRawHeader("Accept-Charset", "utf-8;q=0.7,*;q=0.7");
     request.setRawHeader("Connection", "keep-alive");

     // 使用get方式发起请求
     reply = qnam->get(request);

 /***************如果需要同步********************/
     qRegisterMetaType<QNetworkReply::NetworkError>
 ("QNetworkReply::NetworkError");
     QEventLoop loop; // 使用事件循环使得网络通讯同步进行
     connect(reply, SIGNAL(finished()), &loop, SLOT(quit()));
     connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), this,
             SLOT(slot_httpError(QNetworkReply::NetworkError)));
     loop.exec(); // 进入事件循环， 直到reply的finished()信号发出， 这个语句才能
                         //退出
     slot_httpFinished();
 /**************************************/
 /****************如果需要异步**********************/
     connect(reply, SIGNAL(finished()), this, SLOT(slot_httpFinished()));
     qRegisterMetaType<QNetworkReply::NetworkError>("QNetworkReply::NetworkError");
     connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), this,
             SLOT(slot_httpError(QNetworkReply::NetworkError)));
 /**************************************/
 }

 void GrabThread::slot_httpFinished()
 {
     int http_status = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();

     reply->close();
     reply->deleteLater();

     // 判断是否是重定向
     if (http_status == 302)
     {
         startQuery(reply->rawHeader("Location"));
     }else
     {
         QString reply_content = QString::fromUtf8(reply->readAll());
         if (reply->error() == QNetworkReply::NoError)
         {
             saveToFile(reply_content);
         }else
         {
             qDebug() << "ERROR:" << query_word << " CODE:" << reply->error();
         }
     }
 }

 void GrabThread::slot_httpError(QNetworkReply::NetworkError)
 {

 }

 void GrabThread::saveToFile(QString & html_content)
 {
     QFile file("html/" + query_word + ".html");
     file.open(QIODevice::WriteOnly);
     file.write(file_content.toUtf8());
     file.close();
 }