基于扩展名vb.net获取文件类型

我需要根据上传图像的文件类型为每个组显示默认图像。就是

我有文件组作为

{.jpeg、.jpg、.png、.bmp、.gif、.tif}的图片 {.doc、.docx、.txt、.htm、.html、.xml、.xaml、.css}的文档 excel用于{.xls、.xlsx、.xlt、.xla} pdf格式 {.7z、.APK、.BAT、.rar、.dll、.jar、.zip}的zip 如果输入扩展名是.xls，那么我需要输出为excel

我试过选择案例

<>但是代码非常冗长，我怎么能简短呢？

你可以使用这种操作的概念：考虑下面的代码

Private Sub getfileType_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles getfileType.Click
    Dim array As String()
    Dim extensionType As String
    Dim dics As New Dictionary(Of String, String()) From { _
    {"picture", New String() {".jpeg", ".jpg", ".png", ".bmp", ".gif", ".tif"}}, _
    {"document", New String() {".doc", ".docx", ".txt", ".htm", ".html", ".xml", ".xaml", ".css"}}, _
    {"excel", New String() {".xls", ".xlsx", ".xlt", ".xla"}}, _
    {"pdf", New String() {".pdf"}}, _
    {"zip", New String() {".7z", ".APK", ".BAT", ".rar", ".dll", ".jar", ".zip"}}, _
    {"ppt", New String() {".ppt", ".pos", ".pps"}}}
    Dim pair As KeyValuePair(Of String, String())
    For Each pair In dics
        If attachmentType(pair.Key, pair.Value, ".APK") = True Then
            extensionType = pair.Key
            Exit For
        End If
    Next
    MsgBox("File Type is :" & extensionType)
End Sub

Public Function attachmentType(ByVal input As String, ByVal array() As String, ByVal search As String) As Boolean
    Dim temp As Integer = 0
    For i As Integer = 0 To array.Length - 1
        If array(i) = search Then temp = 1
    Next
    If temp = 1 Then
        attachmentType = True
    Else
        attachmentType = False
    End If
End Function

您可以使用这种操作的概念：考虑下面的代码

Private Sub getfileType_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles getfileType.Click
    Dim array As String()
    Dim extensionType As String
    Dim dics As New Dictionary(Of String, String()) From { _
    {"picture", New String() {".jpeg", ".jpg", ".png", ".bmp", ".gif", ".tif"}}, _
    {"document", New String() {".doc", ".docx", ".txt", ".htm", ".html", ".xml", ".xaml", ".css"}}, _
    {"excel", New String() {".xls", ".xlsx", ".xlt", ".xla"}}, _
    {"pdf", New String() {".pdf"}}, _
    {"zip", New String() {".7z", ".APK", ".BAT", ".rar", ".dll", ".jar", ".zip"}}, _
    {"ppt", New String() {".ppt", ".pos", ".pps"}}}
    Dim pair As KeyValuePair(Of String, String())
    For Each pair In dics
        If attachmentType(pair.Key, pair.Value, ".APK") = True Then
            extensionType = pair.Key
            Exit For
        End If
    Next
    MsgBox("File Type is :" & extensionType)
End Sub

Public Function attachmentType(ByVal input As String, ByVal array() As String, ByVal search As String) As Boolean
    Dim temp As Integer = 0
    For i As Integer = 0 To array.Length - 1
        If array(i) = search Then temp = 1
    Next
    If temp = 1 Then
        attachmentType = True
    Else
        attachmentType = False
    End If
End Function

---

可以为每行指定多个案例条件：

Select Case search
    Case ".doc", ".docx", ".txt"
        extensionType = "document"
    Case ".jpeg", ".jpg", ".png", ".bmp"
        extensionType = "picture"
End Select

或者您也可以使用dict，但将扩展名作为键：

Dim map As New Dictionary(Of String, String)
map.Add(".doc", "document")
map.Add(".docx", "document")
map.Add(".jpg", "picture")
map.Add(".png", "picture")
Console.WriteLine(map(".docx"))

---

可以为每行指定多个案例条件：

Select Case search
    Case ".doc", ".docx", ".txt"
        extensionType = "document"
    Case ".jpeg", ".jpg", ".png", ".bmp"
        extensionType = "picture"
End Select

或者您也可以使用dict，但将扩展名作为键：

Dim map As New Dictionary(Of String, String)
map.Add(".doc", "document")
map.Add(".docx", "document")
map.Add(".jpg", "picture")
map.Add(".png", "picture")
Console.WriteLine(map(".docx"))