這裡使用了curl網路庫和使用多執行緒來下載對應https連結的檔案
對應的.h標頭檔案：
#pragma once #include <iostream> #include <fstream> #include <curl/curl.h> #include <pthread.h> #include <sys/mman.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/types.h> #include <string.h> #include <unistd.h> #include <errno.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> using namespace std; #define THREADS_NUMS (10) class FileInfo { public: void * pFile; size_t offset; size_t endpos; char * pUrl; pthread_t tid; size_t used; FILE * file; size_t totalLen; }; size_t writeFile(void *pData, size_t dwSize, size_t dwMemb, void * pFile); int progress_callback(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow); void * works(void * arg); void sighandler_func(int arg); class DownFile { public: virtual bool downFile()=0; }; class HttpDownFile:public DownFile { public: HttpDownFile(char * pUrl, char * pFile):m_pUrl(pUrl),m_pFile(pFile){ if(SIG_ERR==signal(SIGINT,sighandler_func)) { cout<<"signal error"<<endl; } } virtual bool downFile(); private: double getFileLength(); long lastLen=0; char * m_pUrl; //需要下載的http連線 char * m_pFile; //本地儲存檔案的位置 };
其中，
writeFile函式主要處理將伺服器上的檔案下載到本地上。對應CURLOPT_WRITEFUNCTION
progress_callback函式用來計算下載進度。對應CURLOPT_PROGRESSFUNCTION
sighandler_func函式處理ctrl+c後，儲存當前的下載進度
works函式，各執行緒的處理函式
HttpDownFile::getFileLength 用來獲取需要下載檔案的大小
這裡使用了mmap（記憶體對映）來讓各執行緒同步寫本地放置下載檔案的檔案。
具體的函式實現如下：
#pragma once #include "advanDown.h" FileInfo m_cFiles[THREADS_NUMS+1]; long dwLen=0; double HttpDownFile::getFileLength() { CURL * pCurl=curl_easy_init(); if(NULL==pCurl) { cout<<"curl_easy_init error!"<<endl; return false; } curl_easy_setopt(pCurl,CURLOPT_URL,m_pUrl); curl_easy_setopt(pCurl,CURLOPT_HEADER ,1); curl_easy_setopt(pCurl,CURLOPT_NOBODY ,1); CURLcode tRet=curl_easy_perform(pCurl); if(0!=tRet) { cout<<"curl_easy_perform error"<<endl; return false; } double duLd=0; tRet=curl_easy_getinfo(pCurl,CURLINFO_CONTENT_LENGTH_DOWNLOAD,&duLd); curl_easy_cleanup(pCurl); return duLd; } size_t writeFile(void *pData, size_t dwSize, size_t dwMemb, void * pFile) { FileInfo * pFileInfo=(FileInfo *)pFile; cout<<"id: "<<pFileInfo->tid<<" offset: "<<pFileInfo->offset<<endl; memcpy((char *)pFileInfo->pFile+pFileInfo->offset,(char *)pData,dwSize*dwMemb); pFileInfo->offset+=dwSize*dwMemb; pFileInfo->used+=dwSize*dwMemb; return dwSize*dwMemb; } int progress_callback(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow){ if (dltotal != 0) { //printf("%lf / %lf (%lf %%)\n", dlnow, dltotal, dlnow*100.0 / dltotal); long totalUsedLen=0; //long totalLen=0; for(int i=0;i<THREADS_NUMS+1;i++) { totalUsedLen+=m_cFiles[i].used; totalUsedLen+=m_cFiles[i].totalLen; } printf("%ld / %ld (%ld %%)\n",totalUsedLen,dwLen,totalUsedLen*100/dwLen); } return 0; } void * works(void * arg) { FileInfo * pFile=(FileInfo *)arg; CURL * pCurl=curl_easy_init(); if(NULL==pCurl) { cout<<"curl_easy_init error!"<<endl; return NULL; } if(pFile->file) { cout<<"hello"<<endl; fscanf(pFile->file,"%ld-%ld-%ld",&pFile->offset,&pFile->endpos,&pFile->totalLen); } if(pFile->offset>=pFile->endpos-1) { cout<<pFile->tid<<" already downed: "<<pFile->offset<<"--"<<pFile->endpos<<endl; return NULL; } char buffer[64]={0}; snprintf(buffer,64,"%ld-%ld",pFile->offset,pFile->endpos); cout<<"offset/endpos: "<<pFile->offset<<"--"<<pFile->endpos<<endl; //cout<<cFile.tid<<": "<<cFile.offset<<" -- "<<cFile.endpos<<endl; curl_easy_setopt(pCurl,CURLOPT_URL,pFile->pUrl); curl_easy_setopt(pCurl,CURLOPT_WRITEFUNCTION,writeFile); curl_easy_setopt(pCurl,CURLOPT_WRITEDATA ,pFile); curl_easy_setopt(pCurl,CURLOPT_RANGE,buffer); curl_easy_setopt(pCurl,CURLOPT_NOPROGRESS ,0L); curl_easy_setopt(pCurl,CURLOPT_PROGRESSFUNCTION,progress_callback); curl_easy_setopt(pCurl,CURLOPT_PROGRESSDATA,pFile); CURLcode tRet=curl_easy_perform(pCurl); if(0!=tRet) { cout<<"curl_easy_perform error"<<endl; return NULL; } curl_easy_cleanup(pCurl); return NULL; } bool HttpDownFile::downFile() { dwLen=(long)getFileLength(); cout<<"dwLen: "<<dwLen<<endl; int fd=open(m_pFile,O_RDWR|O_CREAT,S_IRUSR|S_IWUSR); if(fd==-1) { cout<<"open failed"<<endl; return false; } if(lseek(fd,dwLen,SEEK_SET)==-1) { cout<<"lseek failed"<<endl; close(fd); return false; } if(write(fd,"",1)!=1) { cout<<"write failed"<<endl; close(fd); return false; } char * filePos=(char *)mmap(NULL,dwLen,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0); if(filePos==MAP_FAILED) { close(fd); cout<<"mmap failed: "<<errno<<endl; return false; } int slice=dwLen/THREADS_NUMS; FILE * file=fopen("downTemp.txt","r+"); //10 threads for(int i=0;i<THREADS_NUMS+1;i++) { m_cFiles[i].offset=i*slice; m_cFiles[i].pUrl=m_pUrl; m_cFiles[i].pFile=filePos; //cFiles[i].used=0; m_cFiles[i].file=file; if(i==THREADS_NUMS) { m_cFiles[i].endpos=dwLen-1; //cFiles[i].totalLen=cFiles[i].endpos-cFiles[i].offset+1; } else { m_cFiles[i].endpos=(i+1)*slice-1; //cFiles[i].totalLen=slice; } pthread_create(&m_cFiles[i].tid,NULL,works,&m_cFiles[i]); usleep(1); } for(int i=0;i<THREADS_NUMS+1;i++) { pthread_join(m_cFiles[i].tid,NULL); } close(fd); munmap(filePos,dwLen); return true; } void sighandler_func(int arg) { cout<<"arg: "<<arg<<endl; int fd=open("downTemp.txt",O_RDWR|O_CREAT,S_IRUSR|S_IWUSR); for(int i=0;i<THREADS_NUMS+1;i++) { m_cFiles[i].totalLen=m_cFiles[i].used; //cout<<"used: "<<cFiles[i].used<<"/"<<cFiles[i].totalLen<<endl; char buffer[64]={0}; snprintf(buffer,64,"%ld-%ld-%ld\n",m_cFiles[i].offset,m_cFiles[i].endpos,m_cFiles[i].totalLen); write(fd,buffer,strlen(buffer)); } close(fd); exit(-1); }