Практическое руководство. Запрос повторяющихся файлов в дереве каталогов (LINQ)
Иногда файлы, имеющие одинаковые имена, могут находиться в нескольких папках. Например, в папке установки Visual Studio несколько папок содержат файл readme.htm. В этом примере демонстрируется выполнение запроса на повторяющиеся имена файлов в указанной корневой папке. Второй пример показывает, как запрашивать файлы, у которых совпадают размер и время создания.
Пример
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 diplay 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 diplay
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
class QueryDuplicateFileNames
{
static void Main(string[] args)
{
// Uncomment QueryDuplicates2 to run that query.
QueryDuplicates();
// QueryDuplicates2();
// Keep the console window open in debug mode.
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
}
static void QueryDuplicates()
{
// Change the root drive or folder if necessary
string startFolder = @"c:\program files\Microsoft Visual Studio 9.0\";
// Take a snapshot of the file system.
System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo(startFolder);
// This method assumes that the application has discovery permissions
// for all folders under the specified path.
IEnumerable<System.IO.FileInfo> fileList = dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories);
// used in WriteLine to keep the lines shorter
int charsToSkip = startFolder.Length;
// var can be used for convenience with groups.
var queryDupNames =
from file in fileList
group file.FullName.Substring(charsToSkip) by file.Name into fileGroup
where fileGroup.Count() > 1
select fileGroup;
// Pass the query to a method that will
// output one page at a time.
PageOutput<string, string>(queryDupNames);
}
// A Group key that can be passed to a separate method.
// Override Equals and GetHashCode to define equality for the key.
// Override ToString to provide a friendly name for Key.ToString()
class PortableKey
{
public string Name { get; set; }
public DateTime CreationTime { get; set; }
public long Length { get; set; }
public override bool Equals(object obj)
{
PortableKey other = (PortableKey)obj;
return other.CreationTime == this.CreationTime &&
other.Length == this.Length &&
other.Name == this.Name;
}
public override int GetHashCode()
{
string str = String.Format("{0}{1}{2}", this.CreationTime, this.Length, this.Name);
return str.GetHashCode();
}
public override string ToString()
{
return String.Format("{0} {1} {2}", this.Name, this.Length, this.CreationTime);
}
}
static void QueryDuplicates2()
{
// Change the root drive or folder if necessary.
string startFolder = @"c:\program files\Microsoft Visual Studio 9.0\Common7";
// Make the the lines shorter for the console display
int charsToSkip = startFolder.Length;
// Take a snapshot of the file system.
System.IO.DirectoryInfo dir = new System.IO.DirectoryInfo(startFolder);
IEnumerable<System.IO.FileInfo> fileList = dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories);
// Note the use of a compound key. Files that match
// all three properties belong to the same group.
// A named type is used to enable the query to be
// passed to another method. Anonymous types can also be used
// for composite keys but cannot be passed across method boundaries
//
var queryDupFiles =
from file in fileList
group file.FullName.Substring(charsToSkip) by
new PortableKey { Name = file.Name, CreationTime = file.CreationTime, Length = file.Length } into fileGroup
where fileGroup.Count() > 1
select fileGroup;
var list = queryDupFiles.ToList();
int i = queryDupFiles.Count();
PageOutput<PortableKey, string>(queryDupFiles);
}
// A generic method to page the output of the QueryDuplications methods
// Here the type of the group must be specified explicitly. "var" cannot
// be used in method signatures. This method does not display more than one
// group per page.
private static void PageOutput<K, V>(IEnumerable<System.Linq.IGrouping<K, V>> groupByExtList)
{
// Flag to break out of paging loop.
bool goAgain = true;
// "3" = 1 line for extension + 1 for "Press any key" + 1 for input cursor.
int numLines = Console.WindowHeight - 3;
// Iterate through the outer collection of groups.
foreach (var filegroup in groupByExtList)
{
// Start a new extension at the top of a page.
int currentLine = 0;
// Output only as many lines of the current group as will fit in the window.
do
{
Console.Clear();
Console.WriteLine("Filename = {0}", filegroup.Key.ToString() == String.Empty ? "[none]" : filegroup.Key.ToString());
// Get 'numLines' number of items starting at number 'currentLine'.
var resultPage = filegroup.Skip(currentLine).Take(numLines);
//Execute the resultPage query
foreach (var fileName in resultPage)
{
Console.WriteLine("\t{0}", fileName);
}
// Increment the line counter.
currentLine += numLines;
// Give the user a chance to escape.
Console.WriteLine("Press any key to continue or the 'End' key to break...");
ConsoleKey key = Console.ReadKey().Key;
if (key == ConsoleKey.End)
{
goAgain = false;
break;
}
} while (currentLine < filegroup.Count());
if (goAgain == false)
break;
}
}
}
В первом запросе для определения соответствия используется простой ключ; при этом происходит поиск файлов с одинаковыми именами, содержимое которых может быть различным. Второй запрос использует составной ключ для сравнения трех свойств объекта FileInfo. Данный запрос с большей вероятностью найдет файлы, имеющие одинаковые имена и схожее или идентичное содержимое.
Компиляция кода
Создайте проект Visual Studio, предназначенный для платформы .NET Framework версии 3.5. По умолчанию в проекте имеются ссылка на файл System.Core.dll и директива using (C#) или пространство имен Imported (Visual Basic) для пространства имен System.Linq. При работе с проектами C# добавьте директиву using для пространства имен System.IO.
Скопируйте этот код в проект.
Нажмите клавишу F5, чтобы скомпилировать и выполнить программу.
Нажмите любую клавишу для выхода из окна консоли.
Отказоустойчивость
Для интенсивного использования операций запроса к содержимому нескольких типов документов и файлов, рассмотрите возможность использования средства поиска Windows Desktop Search.