传统通过 HTTP 表单的方式来上传文件在 Web 中实现是非常简单的，一个表单中加几个域填写上对应的内容提交就可以了，但如果通过 Qt 来实现就相对麻烦一点，不过我都总结好了代码，直接使用就可以了。
需要用到的模块
QNetworkAccessManager 用来发起 GET/POST 请求
QNetworkReply 用来描述响应信息
QHttpMultiPart 用来模拟表单域
QNetworkRequest 用来构建请求地址等信息
Qt 官方简单例子
QHttpMultiPart *multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType);
QHttpPart textPart;
textPart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"text\""));
textPart.setBody("my text");
QHttpPart imagePart;
imagePart.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("image/jpeg"));
imagePart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"image\""));
QFile *file = new QFile("image.jpg");
file->open(QIODevice::ReadOnly);
imagePart.setBodyDevice(file);
file->setParent(multiPart); // we cannot delete the file now, so delete it with the multiPart
multiPart->append(textPart);
multiPart->append(imagePart);
QUrl url("http://my.server.tld");
QNetworkRequest request(url);
QNetworkAccessManager manager;
QNetworkReply *reply = manager.post(request, multiPart);
multiPart->setParent(reply); // delete the multiPart with the reply
// here connect signals etc.
封装后的类
头文件：
#ifndef HTTPUP_LOADER_H
#define HTTPUP_LOADER_H
#include
#include
#include
#include
#include
#include
#include
#include
class HttpUploader : public QObject
{
Q_OBJECT
public:
HttpUploader(const QString& url, QObject* receiver);
~HttpUploader();
void SetPostURL(const QString& url) { url_ = url; }
QString GetPostURL() { return url_; }
bool AddTextField(const QString& key, const QByteArray& value);
bool AddFileField(const QString& key, const QString& file_path);
bool PostRequest();
QNetworkAccessManager* GetNetworkManager() { return net_manager_; }
signals:
private:
QObject* receiver_;
QString url_;
QByteArray post_content_;
// http upload
QNetworkAccessManager* net_manager_ = nullptr;
QNetworkReply* net_reply_ = nullptr;
QHttpMultiPart* multi_part_ = nullptr;
};
#endif // HTTPUP_LOADER_H
实现文件
#include
#include
#include
#include "http_uploader.h"
HttpUploader::HttpUploader(const QString& url, QObject* receiver)
: receiver_(receiver)
, url_(url)
, post_content_(QByteArray())
{
multi_part_ = new QHttpMultiPart(QHttpMultiPart::FormDataType);
net_manager_ = new QNetworkAccessManager(this);
connect(net_manager_, SIGNAL(finished(QNetworkReply*)), receiver, SLOT(onNetworkFinished(QNetworkReply*)));
}
HttpUploader::~HttpUploader()
{
if (multi_part_ != nullptr)
{
delete multi_part_;
}
if (net_manager_ != nullptr)
{
delete net_manager_;
}
}
bool HttpUploader::AddTextField(const QString &key, const QByteArray &value)
{
QHttpPart text_part;
text_part.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"" + key + "\""));
text_part.setBody(value);
multi_part_->append(text_part);
return true;
}
bool HttpUploader::AddFileField(const QString &key, const QString& file_path)
{
QHttpPart file_part;
QFileInfo upload_file_info(file_path);
file_part.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("application/octet-stream"));
file_part.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"" + key + "\"; filename=\"" + upload_file_info.fileName() + "\""));
QFile *file = new QFile(file_path);
file->open(QIODevice::ReadOnly);
file->setParent(multi_part_);
file_part.setBodyDevice(file);
multi_part_->append(file_part);
return true;
}
bool HttpUploader::PostRequest()
{
QNetworkRequest request = QNetworkRequest(QUrl(url_));
net_reply_ = net_manager_->post(request, multi_part_);
multi_part_->setParent(net_reply_); // delete the multiPart with the reply
connect(net_reply_, SIGNAL(finished()), receiver_, SLOT(onReplyFinished()));
connect(net_reply_, SIGNAL(uploadProgress(qint64, qint64)), receiver_, SLOT(onUploadProgress(qint64, qint64)));
return true;
}
外部调用时，像下面这样调用就可以了
HttpUploader* uploader_ = new HttpUploader(report_url_, this);
uploader_->AddTextField("userId", report_id_.toUtf8());
uploader_->AddTextField("reportContent", comment_.toUtf8());
uploader_->AddFileField("logFile", report_zip_file_);
...
uploader_->PostRequest();
在 new 上传对象的指针时，第二个传递的参数是当前类的一个指针，你需要实现 onNetworkFinished，onReplyFinished，onUploadProgress，来监视上传任务的进度和完成信息，当然你可以自己封装一下，上传对象仅仅提供信号，需要时在外部 connect 就可以了。onNetworkFinished 和 onReplyFinished 的区别是，onReplyFinished 槽函数对应 QNetworkReply 的 finished 信号，他仅仅通知完成了，不会携带任何参数。但是你可以通过 QNetworkReply 的实例对象来获取各种返回值信息。而 onNetworkFinished 槽函数对应的是 QNetworkAccessManager 的 finished 信号，其会携带一个 QNetworkReply 对象指针，你只需要在这里处理返回的对应错误码就可以了。
返回值处理
我使用 QNetworkAccessManager 的 finished 信号来接收完成事件，在 onNetworkFinished 函数中，我们接收到的信息是一个 reply 对象。你可以通过 reply 对象获取 HTTP 返回值：
QVariant variant = reply->attribute(QNetworkRequest::HttpStatusCodeAttribute);
QDebug() << variant.toInt();
也可以打印 Qt 自由的一套返错误代码
qDebug() << reply->error();
qDebug() << reply->errorString();
如果没有错误的情况下，你可以使用 reply 对象获取返回的内容：
qDebug() << reply->readAll();
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