首先，应当从ISequentialStream派生一个类，其头文件如下（SeqStream.h）：

//SeqStream.h

#if !defined (CSEQSTREAM_H)

#define CSEQSTREAM_H

class CSeqStream : public ISequentialStream

{

public:

    //Constructors

    CSeqStream();

    virtual ~CSeqStream();

    virtual BOOL Seek(ULONG iPos);

    virtual BOOL Clear();

    virtual BOOL CompareData(void* pBuffer);

    virtual ULONG Length()  { return m_cBufSize; };

    virtual operator void* const() { return m_pBuffer; };

    STDMETHODIMP_(ULONG)    AddRef(void);

    STDMETHODIMP_(ULONG)    Release(void);

    STDMETHODIMP QueryInterface(REFIID riid, LPVOID *ppv);

    STDMETHODIMP Read(

            /* [out] */ void __RPC_FAR *pv,

            /* [in]  */ ULONG cb,

            /* [out] */ ULONG __RPC_FAR *pcbRead);

    STDMETHODIMP Write(

            /* [in] */ const void __RPC_FAR *pv,

            /* [in] */ ULONG cb,

            /* [out]*/ ULONG __RPC_FAR *pcbWritten);

        void ResetPosition();

protected:

    //Data

private:

    ULONG       m_cRef;         // reference count

    void*       m_pBuffer;      // buffer

    ULONG       m_cBufSize;     // buffer size

    ULONG       m_iPos;         // current index position in the buffer

};

#endif

实现文件如下（SeqStream.cpp）：

#include "stdafx.h"

#include "SeqStream.h "

CSeqStream::CSeqStream()

{

    m_iPos         = 0;

    m_cRef         = 0;

    m_pBuffer      = NULL;

    m_cBufSize     = 0;

    //The constructor AddRef's

    AddRef();

}

CSeqStream::~CSeqStream()

{

    //Shouldn't have any references left

//    ASSERT(m_cRef == 0);

    CoTaskMemFree(m_pBuffer);

}

ULONG    CSeqStream::AddRef(void)

{

    return ++m_cRef;

}

ULONG    CSeqStream::Release(void)

{

//    ASSERT(m_cRef);

    if(--m_cRef)

        return m_cRef;

    delete this;

    return 0;

}

HRESULT CSeqStream::QueryInterface(REFIID riid, void** ppv)

{

//    ASSERT(ppv);

    *ppv = NULL;

    if (riid == IID_IUnknown)

        *ppv = this;

    if (riid == IID_ISequentialStream)

        *ppv = this;

    if(*ppv)

    {

        ((IUnknown*)*ppv)->AddRef();

        return S_OK;

    }

    return E_NOINTERFACE;

}

BOOL CSeqStream::Seek(ULONG iPos)

{

    //Make sure the desired position is within the buffer

//    ASSERT(iPos == 0 || iPos < m_cBufSize);

    //Reset the current buffer position

    m_iPos = iPos;

&nbs

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