powershell-Does（获取物品$file）。GetHashCode（）像get filehash一样动态计算哈希，还是使用预先计算的哈希？

我们正在开发一个用于法医基线分析的PowerShell脚本，该脚本在文件系统上递归迭代，记录目录和文件的层次结构，文件名映射到哈希，并将数据转储到JSON。因为我们对系统中的每个文件都感兴趣，所以它需要尽可能快。

小型测试目录的理想输出如下：

{
    "\\3D Objects":  {

                     },
    "\\Contacts":  {

                   },
    "\\Desktop":  {
                      "\\that":  {
                                     "\\somedoc":  "@{textdoc.txt=C700784FAD1A992A90D71CBC1ADB0F22BF286AD6FE4C9BF42A0407BAF8F3D068}",
                                     "bruh.txt":  "E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855",
                                     "eula.lnk":  "FD068EACB3CC0C1ED2F246542426680F255614791BCD4E0EC615A4B1CEF1F0FA"
                                 },
                      "\\this":  {
                                     "\\another folder":  "@{\\kelp=; thebesometext.txt=BE47BDE1B74F38E47064C1185A1AC8261C9EEEBE9D32ACF25047F5BC4EB5BC8D}",
                                     "ok.txt":  "C5273884B90D490134E7737B29A65405CEA0F7BB786CA82C6337CEB24DE6F5ED",
                                     "sample.txt":  "766D6A6A2330070C98D2AD44C9A4345DB8C6E65BAECC82B6D2CF801126F98DF6"
                                 },
                      "192.168.176.131_Scraped_Files.zip":  "153891A4A3951D9D86C0DFC3F1D9B5FB7886EC754237B078C5657E271A8EC5FB",
                      "bruh.rar":  "BA9B9AD700B82029AEC0DAE52B06E4A09C60255D996DD5A40F7DED61D3DD2795",
                      "FileSystemtoJSON.ps1":  "2E8C2CDFD495DB137B7B46A7FDAC6040E51CD6464D5B9C84B67F179D2B7A9C2B",
                      "File_Scraper.ps1":  "7BFD3600894D39CEEB1BE921C24A3BCDB58C4CE1114D376DB908A95F2CF49FC1",
                      "FStoJson.ps1":  "FACF2C77FA004502C10066E8757D31B1A134878345965F60B80D5CC7CF2A2B44"
                  },
    "\\Documents":  {
                        "\\WindowsPowerShell":  {

                                                }
                    },
    "\\Downloads":  {
                        "winrar-x64-611.exe":  "24FC7955FADA6B9802F4E50E935EBD5654FD7382FAF641B27DD626F4B3563974"
                    },
    "\\Favorites":  {
                        "\\Links":  {

                                    },
                        "Bing.url":  "E0C0A5A360482B5C5DED8FAD5706C4C66F215F527851AD87B31380EF6060696E"
                    },
    "\\Links":  {
                    "Desktop.lnk":  "B559BF8483620D2C64B12901AAC7CAB21219F750E97FFC7FFC2808A7B5B9648D",
                    "Downloads.lnk":  "A0F8549CAB3926988971D8738CB9DE27964B6B47707674A3419DDCCA82935565"
                },
    "\\Music":  {

                },
    "\\OneDrive":  {

                   },
    "\\Pictures":  {
                       "\\Camera Roll":  {

                                         },
                       "\\Saved Pictures":  {

                                            }
                   },
    "\\Saved Games":  {

                      },
    "\\Searches":  {
                       "winrt--{S-1-5-21-321011808-3761883066-353627080-1000}-.searchconnector-ms":  "3B33937704E0EBEC50DD91E982DD4CADDC1ED0DB23864AB28A14A43910C393D0"
                   },
    "\\Videos":  {

                 }
}

我们最初的剧本是这样的：

$root = [PSCustomObject]@{}

function FSSkimmer {
Param(
[Parameter(Mandatory=$True)][string]$path,
[Parameter(Mandatory=$True)][PsCustomObject]$currentobject)

$paths = gci $path | Select-Object -ExpandProperty Fullname
    foreach ($file in $paths) { 
        if (!$(get-item $file | Select-Object -ExpandProperty PSiscontainer)) {
            $name = get-item $file | Select-Object -ExpandProperty Name
            $hash = Get-FileHash $file -Algorithm SHA256 | Select-Object -ExpandProperty Hash
            $currentobject | Add-Member -MemberType NoteProperty -Name $name -Value $hash
        }
        else {
            $dir_name = get-item $file | Select-Object -ExpandProperty Name
            $dir = [PSCustomObject]@{}
            $currentobject | Add-Member -MemberType NoteProperty -Name "\$($dir_name)" -Value $(FSSkimmer -path $file -currentobject $dir)
        }
    }
return $currentobject
}

$null = FSSkimmer -path "C:\" -currentobject $root

ConvertTo-Json -InputObject $root

这太慢了。将哈希算法从Sha-256减少到计算成本更低的算法确实有助于提高速度。但我注意到了另一种选择：

(get-item $file).GetHashCode()

这种方法有什么根本不同之处吗get-filehash? 它使用的是windows存储的预先计算的哈希吗？（我知道文件资源管理器在你提取属性时会显示一个散列，但不知道这个散列是在每次文件写入时缓存的，还是在每次属性打开时动态计算的。出于某种原因，我怀疑这可能与PS中公开的功能相同。