<span style="font-size:18px;">#include "accessweather.h"

#include <QDebug>
#include <QEventLoop>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QNetworkAccessManager>

#include <boost/config.hpp>

AccessWeather::AccessWeather(QObject *parent)
	: QObject(parent)
{
	m_accessWeather = new QNetworkAccessManager(this);
	connect(m_accessWeather, 
		SIGNAL(finished ( QNetworkReply * )),
		this, 
		SLOT(slotFinished ( QNetworkReply * ))
		);
}

AccessWeather::~AccessWeather()
{

}

QString AccessWeather::getWeather( const QString& city )
{
	QNetworkRequest req;
	populateRequest(city, &req);
	m_accessWeather->get(req);

	//wait for get weather
	QEventLoop loop;
	connect(m_accessWeather, SIGNAL(finished ( QNetworkReply * )), &loop, SLOT(quit()));

	return QString();
}

void AccessWeather::slotFinished( QNetworkReply * reply)
{
	QNetworkReply::NetworkError err = reply->error();
	if(QNetworkReply::NoError != err)
		return;

	QUrl newUrl = reply->attribute(QNetworkRequest::RedirectionTargetAttribute).toUrl();
	if (!newUrl.isEmpty())
	{
		//读取新的地址
		m_accessWeather->get(QNetworkRequest(newUrl));
	}
	else
	{
		QByteArray ba = reply->readAll();
		qDebug()<<ba;
	}
	
	int bp = 0;
}

void AccessWeather::populateRequest( const QString& city, QNetworkRequest* req )
{
	QString percentEncode = city.toLocal8Bit().toPercentEncoding();
	QString strReqestLine = QString("http://www.tianqi.com/index.php?c=tianqi&a=search&city=%1").arg(percentEncode);

	<strong><span style="color:#ff6666;">//如果不使用这个，则会导致url.encodedQuery()重新的错误解析而导致错误(编码格式问题)</span></strong>
	QUrl url = QUrl::fromEncoded(strReqestLine.toAscii());

	QString rurl = url.encodedPath();
	QString rurl2 = url.encodedQuery();

	req->setUrl(url);
	
	<strong><em><u><span style="color:#cc0000;">//req->setRawHeader("Host", "http://www.tianqi.com/");//不需要设置Host，默认会有，否则会导致错误的信息提交而获取不到正确信息</span></u></em>

	<em><span style="color:#ff0000;">//下列信息可有可无，如果没有则会有默认的值
	req->setRawHeader("Connection", "keep-alive");
	req->setRawHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.101 Safari/537.36");
	req->setRawHeader("Referer", "http://www.tianqi.com/");
	req->setRawHeader("Accept-Encoding", "gzip,deflate,sdch");
	req->setRawHeader("Accept-Language", "zh-CN,zh;q=0.8");
	req->setRawHeader("Cookie", "cityPy=baoding; AJSTAT_ok_pages=1; AJSTAT_ok_times=1; bdshare_firstime=1412864742830");
	req->setRawHeader("Content-Type", "text/html; charset=GBK");</span></em></strong>

	//GET /index.php?c=tianqi&a=search&city=%E7%9F%B3%E5%AE%B6%E5%BA%84 HTTP/1.1\r\n //直接使用中文'石家庄'而导致的错误
	//不使用QUrl::fromEncoded而导致的错误，会将%重新解析为%25
	//GET /index.php?c=tianqi&a=search&city=%25%CA%25%AF%25%BC%25%D2%25%D7%25%AF HTTP/1.1\r\n
	//正确的提交结果
	//GET /index.php?c=tianqi&a=search&city=%CA%AF%BC%D2%D7%AF HTTP/1.1\r\n
}
</span>

QNetworkAccessManger的用法