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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