Menghitung Layanan

Aplikasi WpdServicesApiSample menyertakan kode yang menunjukkan bagaimana aplikasi dapat menghitung semua layanan Kontak yang ditemukan di salah satu perangkat yang saat ini terhubung ke komputer.

Ketika pengguna memilih opsi "0" di baris perintah, aplikasi memanggil metode EnumerateContactsServices yang ditemukan dalam modul ServiceEnumeration.cpp. Metode ini menampilkan daftar semua perangkat tersambung yang mendukung layanan Kontak.

Misalnya, jika WpdServiceSampleDriver adalah satu-satunya perangkat yang diinstal, aplikasi mengembalikan tiga bidang data: Nama yang Mudah Diingat ("Perangkat Sampel"), Produsen ("Grup Perangkat Portabel Windows"), dan, Deskripsi ("Perangkat Layanan Kontak 2000").

Metode EnumerateContactsServices menyelesaikan tugas-tugas berikut:

• Membuat antarmuka IPortableDeviceManager untuk menangani enumerasi perangkat yang diinstal.
• Membuat antarmuka IPortableDeviceServiceManager untuk menangani enumerasi layanan di setiap perangkat.
• Melakukan iterasi melalui perangkat yang diinstal, mencari layanan Kontak, dan menampilkan informasi perangkat untuk perangkat apa pun yang mendukung layanan ini.

Kode berikut mengilustrasikan metode EnumerateContactsServices .

// Enumerates all Contacts Services, displaying the associated device of each service.
void EumerateContactsServices(CAtlArray<PWSTR>& ContactsServicePnpIDs)
{
    HRESULT                                 hr              = S_OK;
    DWORD                                   cPnpDeviceIDs   = 0;
    PWSTR*                                  pPnpDeviceIDs   = NULL;
    CComPtr<IPortableDeviceManager>         pPortableDeviceManager;
    CComPtr<IPortableDeviceServiceManager>  pServiceManager;

    // CoCreate the IPortableDeviceManager interface to enumerate
    // portable devices and to get information about them.
    hr = CoCreateInstance(CLSID_PortableDeviceManager,
                          NULL,
                          CLSCTX_INPROC_SERVER,
                          IID_PPV_ARGS(&pPortableDeviceManager));

    if (FAILED(hr))
    {
        printf("! Failed to CoCreateInstance CLSID_PortableDeviceManager, hr = 0x%lx\n",hr);
    }        

    // Retrieve the IPortableDeviceServiceManager interface to enumerate device services.
    if (SUCCEEDED(hr))
    {
        hr = pPortableDeviceManager->QueryInterface(IID_PPV_ARGS(&pServiceManager));
        if (FAILED(hr))
        {
            printf("! Failed to QueryInterface IID_IPortableDeviceServiceManager, hr = 0x%lx\n",hr);
        }
    }

    if (SUCCEEDED(hr))
    {
        // First, pass NULL as the PWSTR array pointer to get the total number
        // of devices found on the system.
        hr = pPortableDeviceManager->GetDevices(NULL, &cPnpDeviceIDs);

        if (FAILED(hr))
        {
            printf("! Failed to get number of devices on the system, hr = 0x%lx\n",hr);
        }

        if (SUCCEEDED(hr) && (cPnpDeviceIDs > 0))
        {
            // Second, allocate an array to hold the PnPDeviceID strings returned from
            // the IPortableDeviceManager::GetDevices method
            pPnpDeviceIDs = new (std::nothrow) PWSTR[cPnpDeviceIDs];

            if (pPnpDeviceIDs != NULL)
            {
                DWORD dwIndex = 0;

                hr = pPortableDeviceManager->GetDevices(pPnpDeviceIDs, &cPnpDeviceIDs);
                if (SUCCEEDED(hr))
                {   
                    // For each device found, find the contacts service
                    for (dwIndex = 0; dwIndex < cPnpDeviceIDs; dwIndex++)
                    {
                        DWORD   cPnpServiceIDs = 0;
                        PWSTR   pPnpServiceID  = NULL;

                        // First, pass NULL as the PWSTR array pointer to get the total number
                        // of contacts services (SERVICE_Contacts) found on the device.
                        // To find the total number of all services on the device, use GUID_DEVINTERFACE_WPD_SERVICE.
                        hr = pServiceManager->GetDeviceServices(pPnpDeviceIDs[dwIndex], SERVICE_Contacts, NULL, &cPnpServiceIDs);
                        
                        if (SUCCEEDED(hr) && (cPnpServiceIDs > 0))
                        {                               
                            // For simplicity, we are only using the first contacts service on each device
                            cPnpServiceIDs = 1;
                            hr = pServiceManager->GetDeviceServices(pPnpDeviceIDs[dwIndex], SERVICE_Contacts, &pPnpServiceID, &cPnpServiceIDs);

                            if (SUCCEEDED(hr))
                            {
                                // We've found the service, display it and save its PnP Identifier
                                ContactsServicePnpIDs.Add(pPnpServiceID);

                                printf("[%d] ", static_cast<DWORD>(ContactsServicePnpIDs.GetCount()-1));

                                // Display information about the device that contains this service.
                                DisplayDeviceInformation(pServiceManager, pPnpServiceID);

                                // ContactsServicePnpIDs now owns the memory for this string
                                pPnpServiceID = NULL;
                            }
                            else
                            {
                                printf("! Failed to get the first contacts service from '%ws, hr = 0x%lx\n",pPnpDeviceIDs[dwIndex],hr);
                            }
                        }
                    }
                }

                // Free all returned PnPDeviceID strings
                FreePortableDevicePnPIDs(pPnpDeviceIDs, cPnpDeviceIDs);

                // Delete the array of PWSTR pointers
                delete [] pPnpDeviceIDs;
                pPnpDeviceIDs = NULL;

            }
            else
            {
                printf("! Failed to allocate memory for PWSTR array\n");
            }            
        }
    }
    
    printf("\n%d Contacts Device Service(s) found on the system\n\n", static_cast<DWORD>(ContactsServicePnpIDs.GetCount()));
}

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