操作說明：查詢樹狀目錄中的重複檔案 (LINQ) (Visual Basic)
同名的檔案有時可能位於多個資料夾中。 例如，在 Visual Studio 安裝資料夾下，有數個資料夾內含 readme.htm 檔案。 這個範例示範如何查詢所指定根資料夾下的這類重複檔案名稱。 第二個範例示範如何查詢大小和建立時間也相符的檔案。
範例
Module QueryDuplicateFileNames
Public Sub Main()
Dim path As String = "C:\Program Files\Microsoft Visual Studio 9.0\Common7"
QueryDuplicates1(path)
' Uncomment to run this query instead
' QueryDuplicates2(path)
End Sub
Sub QueryDuplicates1(ByVal root As String)
Dim dir As New System.IO.DirectoryInfo(root)
Dim duplicates = From aFile In dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories) _
Order By aFile.Name _
Group aFile By aFile.Name Into newGroup = Group _
Where newGroup.Count() >= 2 _
Select newGroup
' Page the display so that the results can be read.
Dim trimLength = root.Length
PageOutput(duplicates, trimLength)
End Sub
Sub QueryDuplicates2(ByVal root As String)
' This time a composite key is used. This sub finds all files
' that have been copied into multiple subfolders.
Dim dir As New System.IO.DirectoryInfo(root)
Dim duplicates = From aFile In Dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories) _
Order By aFile.Name _
Group aFile By aFile.Name, aFile.CreationTime, aFile.Length Into newGroup = Group _
Where newGroup.Count() >= 2 _
Select newGroup
' Page the display so that the results can be read.
Dim trimLength = root.Length
PageOutput(duplicates, trimLength)
End Sub
' Pages console display for large query results. No more than one group per page.
' This sub specifically works with group queries of FileInfo objects
' but can be modified for any type.
Sub PageOutput(ByVal groupQuery, ByVal charsToSkip)
' "3" = 1 line for extension key + 1 for "Press any key" + 1 for input cursor.
Dim numLines As Integer = Console.WindowHeight - 3
' Flag to indicate whether there are more results to display
Dim goAgain As Boolean = True
For Each fg As IEnumerable(Of System.IO.FileInfo) In groupQuery
' Start a new extension at the top of a page.
Dim currentLine As Integer = 0
Do While (currentLine < fg.Count())
Console.Clear()
' Get the next page of results
' No more than one filename per page
Dim resultPage = From file In fg _
Skip currentLine Take numLines
' Execute the query. Trim the paths in the output.
For Each line In resultPage
Console.WriteLine(vbTab & line.FullName.Substring(charsToSkip))
Next
' Advance the current position
currentLine = numLines + currentLine
' Give the user a chance to break out of the loop
Console.WriteLine("Press any key for next page or the 'End' key to exit.")
Dim key As ConsoleKey = Console.ReadKey().Key
If key = ConsoleKey.End Then
goAgain = False
Exit For
End If
Loop
Next
End Sub
End Module
第一個查詢會使用簡單索引鍵來判斷相符項目；這會尋找同名但內容可能不同的檔案。 第二個查詢會使用複合索引鍵來比對 FileInfo 物件的三個屬性。 此查詢很有可能找到同名以及內容類似或相同的檔案。
編譯程式碼
使用 System.Linq 命名空間的 Imports 陳述式建立 Visual Basic 主控台應用程式專案。
