一、获取文件大小
int64_t CHttpClient::GetFileSize(const std::string &url)
{auto curl = curl_easy_init();if (!curl){curl_easy_cleanup(curl);return -1;}double filesize = -1; //文件大小curl_easy_setopt(curl,CURLOPT_URL, url.c_str());curl_easy_setopt(curl, CURLOPT_HEADER, 1); curl_easy_setopt(curl, CURLOPT_NOBODY, 1); CURLcode res_code = curl_easy_perform(curl); //请求if (res_code != CURLE_OK){curl_easy_cleanup(curl);return -1;}curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &filesize); curl_easy_cleanup(curl);std::cout << "获取文件大小完成:" << (int64_t)filesize << std::endl;return filesize;
}二、划分线程
auto client = GetClient();auto length = client->GetFileSize(url);
//根据线程数划分块大小auto blockSize = length / thNum;auto lastBlock = (length % thNum == 0 ? blockSize : blockSize + length % thNum );//启动多个线程进行下载std::vector<std::future<bool>> vecFt;std::vector<std::shared_ptr<INetProtocol>> vecDownload;for (size_t i = 0; i < thNum; i++){auto block = (i == thNum - 1 ? lastBlock : blockSize);auto dlClient = GetClient();vecDownload.push_back(dlClient);vecFt.emplace_back(std::async(std::bind(&INetProtocol::Download, dlClient, url, blockSize * i, block)));}三、下载区间数据
bool CHttpClient::Download(const std::string &url, int64_t offset, int64_t blocksize)
{auto curl = curl_easy_init();if (!curl){curl_easy_cleanup(curl);return false;}auto rangeEnd = offset + blocksize - 1;std::cout << "开始下载数据，区间:" << offset << "-" << rangeEnd << ",块大小:" << blocksize << std::endl;m_blockData = std::make_shared<BlockData>(offset, blocksize);curl_easy_setopt(curl, CURLOPT_URL, url.c_str());curl_easy_setopt(curl, CURLOPT_FTP_RESPONSE_TIMEOUT, 10);curl_easy_setopt(curl, CURLOPT_WRITEDATA, this);curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, CHttpClient::WriteBlock);std::stringstream ss;ss << offset << "-" << rangeEnd;curl_easy_setopt(curl, CURLOPT_RANGE, ss.str().c_str());CURLcode res_code = curl_easy_perform(curl);if (res_code != CURLE_OK){curl_easy_cleanup(curl);return false;}std::cout << "下载数据:" << offset << "-" << rangeEnd << ", 获取数据：" << m_blockData->readSize << "完成" << std::endl;curl_easy_cleanup(curl);return true;
}四、等待所有线程完成
//同步等待所有线程完成bool isFaild = false;for (auto i = 0; i < vecFt.size(); i++){if (!vecFt[i].get()){isFaild = true;std::cout << "线程：" << i << "下载失败" << std::endl;} }五、合并线程数据
void CDownload::MergerData(const std::string &fileName, std::vector<std::shared_ptr<INetProtocol>>& vecDownload)
{std::ofstream fout(fileName, std::ios::out | std::ios::binary);if (!fout){throw std::runtime_error("create local file faild");}for (auto& item : vecDownload){fout << item->GetStream().rdbuf();}}6、获取服务器文件MD5
std::string CHttpClient::GetContextMd5(const std::string &url)
{auto curl = curl_easy_init();if (!curl){curl_easy_cleanup(curl);return std::string();}curl_easy_setopt(curl,CURLOPT_URL, url.c_str());curl_easy_setopt(curl, CURLOPT_HEADER, 1); curl_easy_setopt(curl, CURLOPT_NOBODY, 1); std::string strMd5;curl_easy_setopt(curl, CURLOPT_HEADERDATA, &strMd5);curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, CHttpClient::ReadHeader);CURLcode res_code = curl_easy_perform(curl); //请求if (res_code != CURLE_OK){curl_easy_cleanup(curl);return std::string();}curl_easy_cleanup(curl);std::cout << "获取Md5完成:" << strMd5 << std::endl;return strMd5;
}7、检验文件MD5是否一致
bool CDownload::CheckFile(const std::string &url, const std::string& strLocalFile)
{auto client = GetClient();auto contextMd5 = client->GetContextMd5(url);auto localMd5 = GetContentMd5(strLocalFile);std::cout << "context md5:" << contextMd5 << std::endl;std::cout << "local file md5:" << localMd5 << std::endl;if (contextMd5 != localMd5){std::cout << "md5 校验失败， 文件下载失败" << std::endl;return false;}std::cout << "md5 校验一致， 文件下载成功" << std::endl;return true;
}//获取本地文件MD5，然后通过Base64编码输出
std::string CDownload::GetContentMd5(const std::string &fileName)
{std::ifstream fin(fileName, std::ios::in | std::ios::binary);if (!fin){throw std::runtime_error("获取文件MD5失败，文件打开失败");}EVP_MD_CTX *mdctx;unsigned char *md5_digest;unsigned int md5_digest_len = EVP_MD_size(EVP_md5());mdctx = EVP_MD_CTX_new();EVP_DigestInit_ex(mdctx, EVP_md5(), NULL);const int bufSize = 4 * 1024 * 1024;char *pszBuf = new char[bufSize];while (!fin.eof()){fin.read(pszBuf, bufSize);EVP_DigestUpdate(mdctx, pszBuf, fin.gcount());}md5_digest = (unsigned char *)OPENSSL_malloc(md5_digest_len);EVP_DigestFinal_ex(mdctx, md5_digest, &md5_digest_len);EVP_MD_CTX_free(mdctx);delete[] pszBuf;return CBase64::encode(std::string((char*)md5_digest, md5_digest_len));
}如需完整代码，可评论区留言
)
