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CoInitialize CoInitializeEx 是用来初始化COM运行环境的。OleInitial--ize是初始化Ole的运行环境，Ole是在Com的基础上作的扩展，是ActiveX运行的基础，OleInitialize肯定会调用CoInitialize。
CoInitialize、CoInitializeEx都是windows的API，主要是告诉windows以什么方式为程序创建COM对象，原因是程序调用com库函数（除CoGetMalloc和内存分配函数）之前必须初始化com库。 CoInitialize指明以单线程方式创建。 CoInitializeEx可以指定COINIT_MULTITHREADED以多线程方式创建。 创建单线程方式的COM服务器时不用考虑串行化问题，多线程COM服务器就要考虑。 CoInitialize并不装载com库，这个函数只是用来初始化当前线程使用什么样的套间。当使用这个函数以后，线程就和一个套间建立了对应关系。 线程的套间模式决定了该线程如何调用com对象，是否需要列集等 套间是com中用来解决并发调用冲突的很有效的办法 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：新的应用程序应该调用CoInitializeEx而不是CoInitialize，否则就会有必要在之后每个调用Com的线程中调用CoInitialize来初始化出每个线程自己的套间。AfxOleInit实际上调用了OleInitialize，虽然它在内部也调用了CoInitializeEx，但它只能处理单线程，这是AfxOleInit和CoInitialize主要区别： 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.应用：1. CoInitialize仅仅初始化Com，支持多线程。也就是说如果多线程调用Com接口，必须在每个线程中都调用CoInitialize。2. OleInitialize初始化Com（其实也是调用CoInitializeEx），支持多线程。比CoInitialize多了一下内容：A) ClipboardB) Drag and dropC) Object linking and embedding (OLE)D) In-place activation如果不需要这些，用CoInitialize就可以。3.AfxOleInit是MFC对OleInitialize的封装。貌似不支持多线程，也就是说只能在主进程调用该函数，如果线程需要使用Com必须调用上面的两个来实现初始化。而且MSDN明确标明AfxOleInit不能在MFC的DLL中调用，否则也会造成初始化失败。4.OleInitialize和OleUninitialize()成对使用；CoInitialize和CoUninitialize成对使用；CoInitializeEx和CoUninitialize成对使用；AfxOleInit（）由MFC自动释放。VC++使用ADO访问ACCESS时，出现_RecordsetPtr Open卡或者_ConnectionPtrExcute卡或者_CommandPtrExcute一直卡住等莫名其妙的情况时，而语法又没有错误时，请确定初始化COM函数。MFC程序建议使用AfxOleInit（）。
