多線程斷點續(xù)傳(俗稱分段下載).docx

一種點對點文件斷點續(xù)傳的多線程實現(xiàn)方法1 概述 文件斷點續(xù)傳就是在主機與主機間傳輸文件時，可以將文件分多次傳輸，與非斷點續(xù)傳不同的是，每次傳輸不必傳輸整個文件。斷點續(xù)傳是大型文件數(shù)據(jù)傳輸?shù)暮诵?。本文將以多線程技術(shù)和Socket技術(shù)為依托，介紹大型文件斷點續(xù)傳的實現(xiàn)方法。 2 基本實現(xiàn)思想 多線程斷點續(xù)傳實現(xiàn)的基本思想就是在發(fā)送端（也稱客戶端）將要傳輸?shù)奈募指顬榇笮∠喈?dāng)?shù)亩鄩K，用多個線程，將這些塊同時向目標(biāo)服務(wù)器端發(fā)送；在服務(wù)器端的服務(wù)程序監(jiān)聽數(shù)據(jù)傳輸請求，每當(dāng)接到新的請求，則創(chuàng)建一個新的線程，與客戶端的發(fā)送線程對應(yīng)，接收數(shù)據(jù)，記錄數(shù)據(jù)傳輸進程。 圖1 點對點文件斷點續(xù)傳過程示意圖 圖1是點對點文件斷點續(xù)傳第N塊傳輸過程示意圖。在傳輸發(fā)起端（客戶端），將大型文件事先分割為大小相當(dāng)?shù)腘塊，同時創(chuàng)建N個傳輸線程，連接目標(biāo)端服務(wù)器。當(dāng)服務(wù)器端接收到每一個連接請求后，告知客戶端可以傳輸文件。當(dāng)客戶端接收到可以傳輸文件的消息時，首先向服務(wù)器發(fā)送數(shù)據(jù)傳輸信息塊（包括第幾塊、在塊中的起始位置）請求，當(dāng)服務(wù)器端接收到該請求后，向客戶端發(fā)送數(shù)據(jù)傳輸信息，客戶端然后傳輸數(shù)據(jù)傳輸信息塊指定的數(shù)據(jù)給服務(wù)器端，服務(wù)器端更新數(shù)據(jù)傳輸信息塊。 3 具體實現(xiàn) 在實現(xiàn)過程中我使用了MFC的多線程和Windows的Socket，分客戶端和服務(wù)器端實現(xiàn)。因為數(shù)據(jù)傳輸往往是對等的，所以需要將客戶端和服務(wù)器端集成在一起，在客戶端和服務(wù)器端分別實現(xiàn)后，這是件非常簡單的工作，只需將它們集成在一起即可。下面將分別介紹客戶端和服務(wù)器端的實現(xiàn)。 3.1 關(guān)鍵數(shù)據(jù)結(jié)構(gòu) 文件信息數(shù)據(jù)結(jié)構(gòu) 用于在服務(wù)器端和客戶端之間傳遞文件第N塊的屬性信息，詳細定義如下： structfileinfo int fileno; /文件號 int type; /消息類別 long len; /文件（塊）長度，在客戶端向服務(wù)器端發(fā)送數(shù)據(jù)時，是文件長度； /在服務(wù)器端向客戶端發(fā)送已傳部分的信息時，是應(yīng)該續(xù)傳部分的長度； long seek; /開始位置，標(biāo)識要傳輸數(shù)據(jù)在原文件中的起始位置 char nameMAX_PATH_LEN;/文件名 ; 發(fā)送進度記錄結(jié)構(gòu) 用戶記錄文件傳輸進程，詳細定義如下： structSentInfo long totle; /已經(jīng)成功發(fā)送數(shù)據(jù)的長度； int block; /塊標(biāo)識； long filelen; /文件總長度； int threadno; /負責(zé)傳輸?shù)贜塊數(shù)據(jù)的線程標(biāo)識； CString name; /文件名稱 ; 客戶端類 客戶端文件發(fā)送實例封裝，用戶記錄客戶端文件發(fā)送過程中的屬性信息、已發(fā)送大小、發(fā)送線程句柄、發(fā)送線程狀態(tài)、發(fā)送統(tǒng)計信息等，具體定義是： classCClient:publicCObject protected: /Attributes public: CClient(CString ip); CClient(); SentInfo doinfo; long m_index; /塊索引 BOOL sendOkBLOCK; /塊發(fā)送結(jié)束狀態(tài) CString SendFileName; CString DestIp; /目標(biāo)IP地址 THREADSTATUS SendStatus; int GetBlockIndex(); /獲取當(dāng)前要傳輸文件塊的序號，例如0,1,2 CCriticalSection m_gCS; /Sending File Block Thread Handles HANDLE m_threadBLOCK; /Block Sending Thread Handles Array HANDLE m_ExitThread; /WaitToExitThread Handle HANDLE m_ProcessTrackThread; HANDLE m_hEventKill; /User canceled Event long m_IdxInListCtrl; /Index in ListView long m_lBeginTimeTick; long m_lBytesSent; / Operations public: ; 3.2 客戶端 發(fā)送線程 用于發(fā)送由lpparam參數(shù)指定的Client對象標(biāo)識的文件塊數(shù)據(jù)。具體實現(xiàn)是： /發(fā)送線程主函數(shù) /并行進行的線程，針對每個要發(fā)送的文件有BLOCK個該線程 DWORDWINAPISendThread(LPVOIDlpparam) CClient* pClient=(CClient*)lpparam; int block_index = pClient-GetBlockIndex(); /發(fā)送文件的第m_index塊 /發(fā)送線程 sockaddr_in local; SOCKET m_socket; int rc=0; local.sin_family=AF_INET; local.sin_port=htons(pMainFrm-m_FilePort); local.sin_addr.S_un.S_addr=inet_addr(pClient-DestIp); m_socket=socket(AF_INET,SOCK_STREAM,0); int ret; char m_bufMAX_BUFSIZE; fileinfo file_info; /Connect to Server ret = connect(m_socket,(LPSOCKADDR)&local,sizeof(local); while(ret = SOCKET_ERROR)&(WaitForSingleObject(pClient-m_hEventKill, 0) =WAIT_TIMEOUT) closesocket (m_socket); file_info.len = pClient-doinfo.filelen ; if (file_info.len ); /發(fā)送第index塊已發(fā)送大小請求 sendn(m_socket,(char*)&file_info,PROTOCOL_HEADSIZE); long nRead = readn(m_socket,m_buf,PROTOCOL_HEADSIZE); if(nRead len = 0) closesocket (m_socket); /block_index塊是續(xù)傳，且發(fā)送完畢 pClient-goodblock_index = TRUE; return 1; CFile SourceFile; SourceFile.Open(pClient-SendFileName, CFile:modeRead|CFile:typeBinary| CFile:shareDenyNone); /Seek right position of sending file long apos=SourceFile.Seek(pfile_info-seek,CFile:begin); int len1; len1=pfile_info-len; /取得已經(jīng)發(fā)送的長度 if (block_index doinfo.totle += pClient-doinfo.filelen / BLOCK - pfile_info-len; else pClient-doinfo.totle += pClient-doinfo.filelen pClient-doinfo.filelen/BLOCK* (BLOCK - 1) - pfile_info-len; int nBegin = GetTickCount(); int SendTotal = 0; while(len1 0) & (WaitForSingleObject(pClient-m_hEventKill, 0) = WAIT_TIMEOUT) nRead = SourceFile.Read(m_buf, (len1 m_CurrentBlockSize) ? len1:pMainFrm-m_CurrentBlockSize); int send_count=sendn(m_socket,m_buf,nRead); float nLimit; if(send_countdoinfo.totle += send_count; SendTotal += send_count; SourceFile.Close(); shutdown(m_socket,2); closesocket (m_socket); if(len1 goodblock_index = TRUE; return 1; 創(chuàng)建發(fā)送線程 對應(yīng)要發(fā)送的文件，創(chuàng)建BLOCK個線程，負責(zé)發(fā)送各自的數(shù)據(jù)塊。 for(inti=0;i /創(chuàng)建線程，狀態(tài)為停止?fàn)顟B(tài) pClient-m_threadi = :CreateThread(NULL,0,SendThread,(LPVOID)pClient, CREATE_SUSPENDED,&dwthread); :SetThreadPriority(pClient-m_threadi,THREAD_PRIORITY_HIGHEST); 3.3 服務(wù)器端 監(jiān)聽函數(shù) 負責(zé)監(jiān)聽文件傳輸請求，在接受請求后，創(chuàng)建數(shù)據(jù)塊接收線程，具體實現(xiàn)如下： /監(jiān)聽函數(shù) DWORDWINAPIlistenthread(LPVOIDlpparam) SOCKET pSocket=(SOCKET)lpparam; /最多監(jiān)聽MAX_LISTENCOUNT個客戶端連接 int rc=listen(pSocket,MAX_LISTENCOUNT); if (rcm_DestPath + IP + PeerName + - + DestFileName, CFile:modeWrite|CFile:typeBinary| CFile:shareDenyNone) DWORD error = GetLastError(); return; ; long apos = DestFile.Seek(fileseek,CFile:begin); char m_bufMAX_BUFSIZE; CString m_temp; m_temp.Format(%sTempIP%s-%s.%d,pWnd-m_appPath,PeerName, DestFileName,block_index); CFile BlockFile; BlockFile.Open(m_temp, CFile:modeWrite | CFile:typeBinary); while(filelen0) & (WaitForSingleObject(pWnd-m_hEventKill, 0) = WAIT_TIMEOUT) int nRead = readn(so, m_buf, (filelen MAX_BUFSIZE) ? MAX_BUFSIZE : filelen); /Exited if (nRead = 0) CString msg; msg.Format(SOCKET %d Receiving file %s break(Recv 0).,so,DestFileName); pWnd-SendMessage(WM_NEWMSG,(LPARAM)msg.GetBuffer(0),3); msg.ReleaseBuffer(); break; if(nReadSendMessage(WM_NEWMSG,(LPARAM)msg.GetBuffer(0),3); msg.ReleaseBuffer(); break; DestFile.Write(m_buf,nRead); filelen -= nRead; fileseek += nRead; BlockFile.Seek(0,CFile:begin); BlockFile.Write(&fileseek,sizeof(long); BlockFile.Write(&filelen,sizeof(long); pfileinfo-m_seek = fileseek; pfileinfo-m_len = filelen; closesocket (so); /Current Block Received OK BlockFile.Close(); DestFile.Close(); if (filelen canDel = true; 初始化文件數(shù)據(jù)塊信息 負責(zé)初始化文件傳輸時數(shù)據(jù)塊的大小、開始位置等信息。具體實現(xiàn)是： /初始化文件數(shù)據(jù)塊信息 CFileInfoRecving*GetRecvedFileBlock(CStringPeerName,CStringFileName,long& filelen, long&fileseek,intblock_index) CString m_temp; CMainFrame* pWnd = (CMainFrame*) AfxGetMainWnd(); m_temp.Format(%stempIP%s-%s.%d,pWnd-m_appPath,PeerName,FileName,block_index); FILE* fp=NULL; CFile Blockfile; CFile RecvFile; long seek = fileseek; long flen = filelen; CString DestFile = pWnd-m_DestPath + IP + PeerName + - + FileName; bool DestFileNoExist = false; if(fp=fopen(DestFile,r)=NULL) RecvFile.Open(DestFile, CFile:modeCreate|CFile:modeWrite|CFile:typeBinary| CFile:shareDenyNone); RecvFile.Close(); DestFileNoExist = true; if (fp) fclose(fp); CFileInfoRecving* pfileinfo = NULL; /如果目標(biāo)文件不存在或者長度記錄文件不存在，重新傳 if( (fp=fopen(m_temp,r)=NULL) | (DestFileNoExist) /第一次接收 fileseek = block_index*(flen/BLOCK); filelen = flen/BLOCK; if (block_index = (BLOCK - 1) filelen = flen - fileseek; /Add To Recving File List pfileinfo = new CFileInfoRecving(); pfileinfo-m_sFileName = FileName; pfileinfo-m_sPeerName = PeerName; pfileinfo-m_nBlockIndex = block_index; pfileinfo-m_sFileSize.Format(%d,flen); seek = fileseek; flen = filelen; pfileinfo-m_seek = seek; pfileinfo-m_len = flen; pWnd-m_RecvingFileList.AddTail(pfileinfo); Blockfile.Open(m_temp, CFile:modeCreate|CFile:modeWrite| CFile:typeBinary | CFile:shareDenyNone); Blockfile.Write(&seek,sizeof(long); Blockfile.Write(&flen,sizeof(long); Blockfile.Close(); else POSITION pos = pWnd-m_RecvingFileList.GetHeadPosition(); while (pos) pfileinfo = pWnd-m_RecvingFileList.GetAt(pos); if (pfileinfo) if (pfileinfo-m_sFileName = FileName) & (pfileinfo-m_sPeerName = PeerName) & (pfileinfo-m_nBlockIndex = block_index) break; pWnd-m_RecvingFileList.GetNext(pos); Blockfile.Open(m_temp,CFile:modeRead | CFile:typeBinary | CFile:shareDenyNone); Blockfile.Read(&fileseek,sizeof(long); Blockfile.Read(&filelen,sizeof(long); if (pfileinfo = NULL) | (!pos) pfileinfo = new CFileInfoRecving(); pfileinfo-m_sFileName = FileName; pfileinfo-m_sPeerName = PeerName; pfileinfo-m_nBlockIndex = block_index; pfileinfo-m_sFileSize.Forma