Qt--Http请求封装(Get Post)

http://blog.csdn.net/wangshubo1989/article/details/52588938

之前使用c++开发的程序都是使用curl库进行各种http操作。

qt为我们继承了一些网络操作的类，因此不需要第三方库的支持了。今天就跟大家分享一下qt中对http请求的封装。

其中用到了： 
QNetworkRequest 

The QNetworkRequest class holds a request to be sent with QNetworkAccessManager. 
http://doc.qt.io/qt-4.8/qnetworkrequest.html#details

QNetworkAccessManager 

The QNetworkAccessManager class allows the application to send network requests and receive replies. 
http://doc.qt.io/qt-5/qnetworkaccessmanager.html#details

QNetworkReply 

The QNetworkReply class contains the data and headers for a request sent with QNetworkAccessManager. 
http://doc.qt.io/qt-5/qnetworkreply.html#details

这里不再过多的介绍上面三个类，因为qt的文档描述的非常非常的清楚。

开始写我们自己的http api：

写一个基类，命名为BaseAPI: 

baseapi.h

#ifndef BASEAPI_H
#define BASEAPI_H

#include <QSettings>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QNetworkAccessManager>

#include "base/constants.h"

class BaseAPI : public QObject
{
Q_OBJECT

public:
BaseAPI();
~BaseAPI();
void get(const QString url);
void post(const QString url, const QByteArray &data);

protected:
virtual void requestFinished(QNetworkReply *reply, const QByteArray data, const int statusCode) = 0;

public slots:
void serviceRequestFinished(QNetworkReply *reply);

private:
QNetworkRequest httpRequest;
QNetworkAccessManager networkAccessManager;
QSettings *settings;
};

#endif // BASEAPI_H

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baseapi.cc

#include "baseapi.h"

BaseAPI::BaseAPI()
{
httpRequest.setRawHeader("Accept", API_ACCEPT);
httpRequest.setRawHeader("User-Agent", API_USER_AGENT);
httpRequest.setRawHeader("X-XXX-API-Key", API_KEY);
httpRequest.setRawHeader("X-XXX-API-Secret", API_SECRET);
httpRequest.setRawHeader("Accept-Encoding", "gzip, deflate");
httpRequest.setRawHeader("Content-Type", "application/json");

settings = new QSettings("XXX");
QString id = settings->value(SETTING_ACCOUNT_ID, "").toString();
QString token = settings->value(SETTING_ACCOUNT_TOKEN, "").toString();

if(!id.isEmpty()) {
httpRequest.setRawHeader("X-XXX-User-ID", id.toStdString().c_str());
}

if (!token.isEmpty()) {
httpRequest.setRawHeader("X-XXX-User-Token", token.toStdString().c_str());
}

qDebug() << "BaseAPI...id:" << id << " token:" + token;

QObject::connect(&networkAccessManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(serviceRequestFinished(QNetworkReply*)));
}

BaseAPI::~BaseAPI()
{
networkAccessManager.disconnect();
if (settings){
delete settings;
settings = nullptr;
}
}

void BaseAPI::get(const QString url)
{
httpRequest.setUrl(QUrl(url));
networkAccessManager.get(httpRequest);
}

void BaseAPI::post(const QString url, const QByteArray &data)
{
httpRequest.setUrl(QUrl(url));
networkAccessManager.post(httpRequest, data);
}

void BaseAPI::serviceRequestFinished(QNetworkReply *reply)
{
int statusCode = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();

qDebug() << "BaseAPI...serviceRequestFinished...statusCode:" << statusCode;

if(reply->error() == QNetworkReply::NoError) {
requestFinished(reply, reply->readAll(), statusCode);
} else {
requestFinished(reply, "", statusCode);
}

// At the end of that slot, we won't need it anymore
reply->deleteLater();
}

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解释： 

1 使用了qt中的QSettings，就是一个存储功能 

The QSettings class provides persistent platform-independent application settings 
http://doc.qt.io/qt-4.8/qsettings.html

2 声明了一个纯虚函数，使得子类根据自己的情况进行重写

基类就这样写完了，下面写一个应用，比如从服务器请求游戏列表： 

写一个子类GameAPI继承自BaseAPI： 

gameapi.h

#ifndef GAMEAPI
#define GAMEAPI

#include <functional>
#include <QList>
#include <QPair>
#include "baseapi.h"

class GameAPI: public BaseAPI
{
public:
GameAPI();
~GameAPI();
void getGameList(std::function<void(bool, QList<QPair<QString,QString>>)> callback);

protected:
void requestFinished(QNetworkReply* reply, const QByteArray data, const int statusCode);

private:
std::function<void(bool, QList<QPair<QString,QString>>)> checkCallback;
};

#endif // GAMEAPI

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gameapi.cc

#include "gameapi.h"

#include "qdebug.h"

#include <QJsonArray>
#include <QJsonObject>
#include <QJsonDocument>

const QString GET_GAME = QString("https://www.xxx.com").append("/apps");

GameAPI::GameAPI()
{

}

GameAPI::~GameAPI()
{

}

void GameAPI::requestFinished(QNetworkReply* reply, const QByteArray data, const int statusCode)
{
if (statusCode == 200) {
QJsonParseError jsonError;
QJsonArray json_array = QJsonDocument::fromJson(data, &jsonError).array();
if(jsonError.error == QJsonParseError::NoError) {
QList<QPair<QString,QString>> games;
for(int i = 0; i < json_array.size(); ++i) {
QJsonObject json = json_array.at(i).toObject();
games.append(qMakePair(json.value("key1").toString(), json.value("key2").toString()));
}
this->checkCallback(true, games);
return;
}
}
QList<QPair<QString,QString>> games;
this->checkCallback(false, games);
}

void GameAPI::getGameList(std::function<void(bool, QList<QPair<QString,QString>>)> callback)
{
this->checkCallback = callback;
get(GET_GAME);
}

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使用接口：

GameAPI game_api = new GameAPI();
game_api->getGameList([&](bool success, QList<QPair<QString,QString>> games){
if (success)
{
//do something
}
});