愛華網(wǎng)
CoInitialize CoInitializeEx 是用來初始化COM運(yùn)行環(huán)境的。OleInitial--ize是初始化Ole的運(yùn)行環(huán)境，Ole是在Com的基礎(chǔ)上作的擴(kuò)展，是ActiveX運(yùn)行的基礎(chǔ)，OleInitialize肯定會(huì)調(diào)用CoInitialize。
CoInitialize、CoInitializeEx都是windows的API，主要是告訴windows以什么方式為程序創(chuàng)建COM對(duì)象，原因是程序調(diào)用com庫(kù)函數(shù)（除CoGetMalloc和內(nèi)存分配函數(shù)）之前必須初始化com庫(kù)。 CoInitialize指明以單線程方式創(chuàng)建。 CoInitializeEx可以指定COINIT_MULTITHREADED以多線程方式創(chuàng)建。 創(chuàng)建單線程方式的COM服務(wù)器時(shí)不用考慮串行化問題，多線程COM服務(wù)器就要考慮。 CoInitialize并不裝載com庫(kù)，這個(gè)函數(shù)只是用來初始化當(dāng)前線程使用什么樣的套間。當(dāng)使用這個(gè)函數(shù)以后，線程就和一個(gè)套間建立了對(duì)應(yīng)關(guān)系。 線程的套間模式?jīng)Q定了該線程如何調(diào)用com對(duì)象，是否需要列集等 套間是com中用來解決并發(fā)調(diào)用沖突的很有效的辦法 Before calling any COMfunctions, a thread needs to call CoInitialize to load the COMinfrastructure (and to enter an apartment). Once a thread callsCoInitialize, the thread is free to call COM APIs. CoInitializeEx providesthe same functionality as CoInitialize and also provides aparameter to explicitly specify the thread's concurrency model. Thecurrent implementation of CoInitialize calls CoInitializeEx andspecifies the concurrency model as single-thread apartment.Applications developed today should call CoInitializeEx rather thanCoInitialize. 注：新的應(yīng)用程序應(yīng)該調(diào)用CoInitializeEx而不是CoInitialize，否則就會(huì)有必要在之后每個(gè)調(diào)用Com的線程中調(diào)用CoInitialize來初始化出每個(gè)線程自己的套間。AfxOleInit實(shí)際上調(diào)用了OleInitialize，雖然它在內(nèi)部也調(diào)用了CoInitializeEx，但它只能處理單線程，這是AfxOleInit和CoInitialize主要區(qū)別： OleInitialize calls CoInitializeEx internally to initialize the COM library on the current apartment. Because OLE operations are not thread-safe, OleInitialize specifies the concurrency model as single-thread apartment. Once the concurrency model for an apartment is set, it cannot be changed. A call to OleInitialize on an apartment that was previously initialized as multithreaded will fail and return RPC_E_CHANGED_MODE.應(yīng)用：1. CoInitialize僅僅初始化Com，支持多線程。也就是說如果多線程調(diào)用Com接口，必須在每個(gè)線程中都調(diào)用CoInitialize。2. OleInitialize初始化Com（其實(shí)也是調(diào)用CoInitializeEx），支持多線程。比CoInitialize多了一下內(nèi)容：A) ClipboardB) Drag and dropC) Object linking and embedding (OLE)D) In-place activation如果不需要這些，用CoInitialize就可以。3.AfxOleInit是MFC對(duì)OleInitialize的封裝。貌似不支持多線程，也就是說只能在主進(jìn)程調(diào)用該函數(shù)，如果線程需要使用Com必須調(diào)用上面的兩個(gè)來實(shí)現(xiàn)初始化。而且MSDN明確標(biāo)明AfxOleInit不能在MFC的DLL中調(diào)用，否則也會(huì)造成初始化失敗。4.OleInitialize和OleUninitialize()成對(duì)使用；CoInitialize和CoUninitialize成對(duì)使用；CoInitializeEx和CoUninitialize成對(duì)使用；AfxOleInit（）由MFC自動(dòng)釋放。VC++使用ADO訪問ACCESS時(shí)，出現(xiàn)_RecordsetPtr Open卡或者_(dá)ConnectionPtrExcute卡或者_(dá)CommandPtrExcute一直卡住等莫名其妙的情況時(shí)，而語(yǔ)法又沒有錯(cuò)誤時(shí)，請(qǐng)確定初始化COM函數(shù)。MFC程序建議使用AfxOleInit（）。
