上传（这里指的是客户端向服务端上传文件，编写的服务端的代码）
void onUpload(const httplib::Request &req, httplib::Response &res, const httplib::ContentReader &content_reader)
{if(req.is_multipart_form_data()){httplib::MultipartFormDataItems files;content_reader([&](const httplib::MultipartFormData &file){files.push_back(file);return true;}, [&](const char *data, size_t data_length){files.back().content.append(data, data_length);return true;});for(const auto& file : files){if(file.filename.empty()){std::cout << file.name << " : " << file.content << std::endl;}else{//C++ windows下utf-8转gbkchar* ansiStr = utf8_2_ansi(file.filename.c_str(), nullptr);std::string fileName(ansiStr);free(ansiStr);ansiStr = nullptr;std::ofstream ofs("./" + fileName, std::ofstream::trunc | std::ostream::binary);if(ofs.is_open()){ofs.write(file.content.c_str(), file.content.size());ofs.close();}}}}else{//这里好像并没有一个通用的请求头来标识上传文件的文件名,但是可以服务端和客户端约定一个请求头来标识上传的文件名std::string fileName = req.get_header_value("fileName");//C++ Windows环境下utf8转换gbk编码，才能正确打开文件char* ansiStr = utf8_2_ansi(fileName.c_str(), nullptr);fileName.assign(ansiStr);free(ansiStr);ansiStr = NULL;std::ofstream ofs("./" + fileName, std::ofstream::trunc | std::ofstream::binary);if(!ofs.is_open()){res.set_content(R"({"message":"open file failed"})", "appliation/json");return;}//里面的lambda函数可能会调用多次content_reader([&](const char *data, size_t data_length){std::cout << "data_length : " << data_length << std::endl;ofs.write(data, data_length);return true;});ofs.close();}res.set_content(R"({"message":"upload successed"})", "appliation/json");
}
这里可能由于服务器实现的不同，对于客户端的请求头可能有些要求，下面是Qt环境下的httpclient的实现代码
多条信息上传
QHttpMultiPart multiparts;//cpphttplib必须要求这段multiparts.setContentType(QHttpMultiPart::FormDataType);QFile file(ui->lineEdit_2->text());if(!file.open(QIODevice::ReadOnly)){qDebug() << QStringLiteral("读取文件失败");return;}QFileInfo fileInfo(ui->lineEdit_2->text());QString fileName = fileInfo.fileName();QHttpPart filePart;filePart.setBodyDevice(&file);filePart.setHeader(QNetworkRequest::ContentDispositionHeader, QStringLiteral("form-data; name=\"\";filename=\"%1\"").arg(fileName).toUtf8());filePart.setHeader(QNetworkRequest::ContentTypeHeader, "application/octet-stream");QString name = ui->lineEdit_3->text();QString value = ui->lineEdit_4->text();QHttpPart textPart;//不要少写textPart.setHeader(QNetworkRequest::ContentDispositionHeader, QStringLiteral("form-data; name=\"%1\";filename=\"\"").arg(name).toUtf8());textPart.setHeader(QNetworkRequest::ContentTypeHeader, "text/plain");textPart.setBody(value.toUtf8());multiparts.append(textPart);multiparts.append(filePart);QNetworkAccessManager manager;QEventLoop loop;QNetworkRequest request(QUrl("http://192.168.6.2:8530/upload"));connect(&manager, &QNetworkAccessManager::finished, &loop, &QEventLoop::quit);QNetworkReply *reply = manager.post(request, &multiparts);loop.exec();if(reply){qDebug() << reply->readAll();}
单个文件上传
QByteArray fileContent;QFile file(ui->lineEdit->text());if(file.open(QIODevice::ReadOnly)){fileContent = file.readAll();file.close();}else{qDebug() << QStringLiteral("读取文件失败");return;}QFileInfo fileInfo(ui->lineEdit->text());QString fileName = fileInfo.fileName();QNetworkAccessManager manager;QEventLoop loop;connect(&manager, &QNetworkAccessManager::finished, &loop, &QEventLoop::quit);QNetworkRequest request(QUrl("http://192.168.6.2:8530/upload"));request.setRawHeader("fileName", fileName.toUtf8());request.setRawHeader("content-type", "application/octet-stream");QNetworkReply* reply = manager.post(request, fileContent);loop.exec();if(reply){qDebug() << reply->readAll();reply->deleteLater();}
下载 服务端提供服务让客户端来下载
较大的文件
void onDownload(const httplib::Request &req, httplib::Response &res)
{std::ifstream ifs("D:/all-cases/uploadHttpDemo/build/Debug/Git-2.45.2-64-bit.exe", std::ifstream::binary);unsigned long long totalCount = 0;if(ifs){ifs.seekg(0, ifs.end);totalCount = ifs.tellg();ifs.seekg(0, ifs.beg);}else{res.set_content(R"({"msg":"open file failed"})", "application/json");return;}if(totalCount > 0){char* data = new char[totalCount] {};ifs.read(data, totalCount);ifs.close();const unsigned long long chunkedSize = 1024 * 1024 * 10;res.set_header("Content-Disposition", "attachment; filename=\"Git-2.45.2-64-bit.exe\"");res.set_chunked_content_provider("multipart/form-data", [data,totalCount,chunkedSize](size_t offset, httplib::DataSink &sink)->bool{//如果文件大小小于chunkedSize, 直接一次性写完if(totalCount <= chunkedSize){sink.write(data + offset, totalCount);sink.done();return true;}//最后一次写if(offset + chunkedSize >= totalCount){sink.write(data + offset, totalCount - offset);sink.done();return true;}else{//每次写 chunkedSize大小的数据sink.write(data + offset, chunkedSize);}}, [&data](bool success) {delete[]data;data = nullptr;});}
}
较小的文件
void onSmallFile(const httplib::Request &req, httplib::Response &res)
{std::ifstream ifs("D:/all-cases/uploadHttpDemo/build/Debug/如果爱忘了.mp3", std::ifstream::binary);if(ifs){ifs.seekg(0, std::ifstream::end);auto totalCount = ifs.tellg();ifs.seekg(0, std::ifstream::beg);char* data = new char[totalCount]{};ifs.read(data, totalCount);ifs.close();//编码一下否则下载的文件名会乱码const char* type = "inline; filename=\"如果爱忘了.mp3\"";char* utf8Type = ansi_2_utf8(type, nullptr);res.set_header("Content-Disposition", utf8Type);free(utf8Type);res.set_content(data, totalCount, "audio/mp3");delete[] data;data = nullptr;}else{res.set_content(R"({"msg":"open file failed"})", "application/json");}
}
httpclient下载代码使用的是Qt环境
QNetworkAccessManager manager;QEventLoop loop;QNetworkRequest request(QUrl("http://192.168.110.173:8530/downLoad"));connect(&manager, &QNetworkAccessManager::finished, &loop, &QEventLoop::quit);QNetworkReply *reply = manager.get(request);loop.exec();QString fileName;QString str = reply->header(QNetworkRequest::ContentDispositionHeader).toString();QRegularExpression reg("(?<=filename=\").+(?=\")");QRegularExpressionMatch match = reg.match(str);if(match.hasMatch()){fileName = match.captured();}qDebug() << "fileName : " << fileName;if(reply){QFile file("./" + fileName);if(file.open(QIODevice::WriteOnly | QIODevice::Truncate)){file.write(reply->readAll());file.close();}else{qDebug() << QStringLiteral("打开文件失败");}reply->deleteLater();}
对于大小文件都可以