IHttpCoNtext：：MapPath 方法

傳回相對 URL 的實體路徑。

語法

virtual HRESULT MapPath(  
   PCWSTR pszUrl,  
   __out_bcount(* pcbPhysicalPath) PWSTR pszPhysicalPath,  
   DWORD* pcbPhysicalPath  
) = 0;  

參數

pszUrl
[IN]字串的指標，其中包含要對應的相對 URL。

pszPhysicalPath
[OUT]接收對應路徑之字串的指標。

pcbPhysicalPath
[IN]的 DWORD 指標，其中包含 所 pszPhysicalPath 指向之緩衝區的大小。

傳回值

HRESULT。 可能的值包括 (但不限於) 下表中的這些值。

備註

方法會 MapPath 傳回 包含在 參數中 pszUrl 之相對 URL 的實體位置。

範例

下列程式碼範例示範如何使用 MapPath 方法來建立 HTTP 模組，以傳回使用此模組之網站的根資料夾實體路徑。

#define _WINSOCKAPI_
#include <windows.h>
#include <sal.h>
#include <httpserv.h>

// Create the module class.
class MyHttpModule : public CHttpModule
{
public:
    REQUEST_NOTIFICATION_STATUS
    OnBeginRequest(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Retrieve a pointer to the request.
        IHttpRequest * pHttpRequest = pHttpContext->GetRequest();

        // Test for an error.
        if (pHttpRequest != NULL)
        {
            // Length of the returned path.
            DWORD cbPhysicalPath = 0;
            
            // Get the length of the mapped path.
            pHttpContext->MapPath(L"/",NULL,&cbPhysicalPath);
            
            // Allocate space to store the path.
            PWSTR pwszPhysicalPath =
                (PWSTR) pHttpContext->AllocateRequestMemory(cbPhysicalPath+1);
            PSTR pszPhysicalPath  =
                (PSTR) pHttpContext->AllocateRequestMemory(cbPhysicalPath+1);
            
            // Test for an error.
            if ((pwszPhysicalPath==NULL) || (pszPhysicalPath==NULL))
            {
                // Set the error status.
                pHttpContext->GetResponse()->SetStatus(500,"Server Error",0,
                    HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY));
                // End additional processing.
                return RQ_NOTIFICATION_FINISH_REQUEST;
            }
            
            // Retrieve the mapped path.
            pHttpContext->MapPath(L"/",pwszPhysicalPath,&cbPhysicalPath);
            
            // Convert the WCHAR string to a CHAR string.
            wcstombs_s((size_t*)&cbPhysicalPath,pszPhysicalPath,
                cbPhysicalPath,pwszPhysicalPath,cbPhysicalPath);
            
            // Clear the existing response.
            pHttpContext->GetResponse()->Clear();
            // Set the MIME type to plain text.
            pHttpContext->GetResponse()->SetHeader(
                HttpHeaderContentType,"text/plain",
                (USHORT)strlen("text/plain"),TRUE);

                // Return the path information.
            WriteResponseMessage(pHttpContext,
                "Path: ",pszPhysicalPath);

            // End additional processing.
            return RQ_NOTIFICATION_FINISH_REQUEST;
        }

        // Return processing to the pipeline.
        return RQ_NOTIFICATION_CONTINUE;
    }

private:

    // Create a utility method that inserts a name/value pair into the response.
    HRESULT WriteResponseMessage(
        IHttpContext * pHttpContext,
        PCSTR pszName,
        PCSTR pszValue
    )
    {
        // Create an HRESULT to receive return values from methods.
        HRESULT hr;
        
        // Create a data chunk.
        HTTP_DATA_CHUNK dataChunk;
        // Set the chunk to a chunk in memory.
        dataChunk.DataChunkType = HttpDataChunkFromMemory;
        // Buffer for bytes written of data chunk.
        DWORD cbSent;

        // Set the chunk to the first buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszName;
        // Set the chunk size to the first buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszName);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Set the chunk to the second buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszValue;
        // Set the chunk size to the second buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszValue);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Return a success status.
        return S_OK;
    }
};

// Create the module's class factory.
class MyHttpModuleFactory : public IHttpModuleFactory
{
public:
    HRESULT
    GetHttpModule(
        OUT CHttpModule ** ppModule, 
        IN IModuleAllocator * pAllocator
    )
    {
        UNREFERENCED_PARAMETER( pAllocator );

        // Create a new instance.
        MyHttpModule * pModule = new MyHttpModule;

        // Test for an error.
        if (!pModule)
        {
            // Return an error if the factory cannot create the instance.
            return HRESULT_FROM_WIN32( ERROR_NOT_ENOUGH_MEMORY );
        }
        else
        {
            // Return a pointer to the module.
            *ppModule = pModule;
            pModule = NULL;
            // Return a success status.
            return S_OK;
        }            
    }

    void Terminate()
    {
        // Remove the class from memory.
        delete this;
    }
};

// Create the module's exported registration function.
HRESULT
__stdcall
RegisterModule(
    DWORD dwServerVersion,
    IHttpModuleRegistrationInfo * pModuleInfo,
    IHttpServer * pGlobalInfo
)
{
    UNREFERENCED_PARAMETER( dwServerVersion );
    UNREFERENCED_PARAMETER( pGlobalInfo );

    // Set the request notifications and exit.
    return pModuleInfo->SetRequestNotifications(
        new MyHttpModuleFactory,
        RQ_BEGIN_REQUEST,
        0
    );
}

您的模組必須匯出 RegisterModule 函式。 您可以為專案建立模組定義 (.def) 檔案，或使用 參數編譯模組 /EXPORT:RegisterModule 來匯出此函式。 如需詳細資訊，請參閱 逐步解說：使用機器碼建立 Request-Level HTTP 模組。

您可以使用呼叫慣例編譯器代碼， __stdcall (/Gz) 而不是明確宣告每個函式的呼叫慣例。

規格需求

另請參閱

IHttpCoNtext 介面