枚举FOLDERID_NetworkFolder时如何仅显示网络打印机？

原代码枚举了FOLDERID_NetworkFolder下的所有网络设备，要筛选出网络打印机，核心是通过检查ShellItem的打印机属性来过滤。以下是修改后的完整代码：

hr = CoInitialize(NULL);
if (FAILED(hr))
{
    printf("CoInitialize error, %x\n", hr);
    return;
}

hr = SHGetKnownFolderItem(FOLDERID_NetworkFolder, KF_FLAG_DEFAULT, NULL, IID_PPV_ARGS(&pShellItem));
if (FAILED(hr))
{
    printf("SHGetKnownFolderItem error, %x\n", hr);
    return;
}

hr = pShellItem->BindToHandler(nullptr, BHID_EnumItems, IID_PPV_ARGS(&pShellEnum));                
if (FAILED(hr))
{
    printf("BindToHandler error, %x\n", hr);
    return;
}

do {
    IShellItem* pItem = nullptr;
    LPWSTR szName = NULL;
    SFGAOF attributes = 0;

    hr = pShellEnum->Next(1, &pItem, nullptr);
    if (hr == S_OK && pItem)
    {
        // 获取ShellItem属性，检查是否为打印机
        hr = pItem->GetAttributes(SFGAO_PRINTER, &attributes);
        if (SUCCEEDED(hr) && (attributes & SFGAO_PRINTER))
        {
            hr = pItem->GetDisplayName(SIGDN_NORMALDISPLAY, &szName);
            if (SUCCEEDED(hr) && szName != NULL)
            {   
                wcout << szName << std::endl;
                CoTaskMemFree(szName); // 释放字符串资源
            }        
        }
        pItem->Release(); // 释放IShellItem对象
    }
} while (hr == S_OK);

// 释放全局Shell对象
if (pShellEnum) pShellEnum->Release();
if (pShellItem) pShellItem->Release();

CoUninitialize();

system("pause");

修改关键点说明 #

• 打印机属性过滤：调用IShellItem::GetAttributes传入SFGAO_PRINTER标志，判断当前ShellItem是否为打印机设备，网络打印机同样会携带该属性
• 资源泄漏修复：补充CoTaskMemFree释放szName、Release释放IShellItem/IShellEnumItems对象，避免内存泄漏
• 空指针安全：将pItem初始化为nullptr，避免野指针风险

内容的提问来源于stack exchange，提问作者Arun Arun