Dùng nhiều extention để filter tập tin

Hôm nay chúng ta sẽ tìm hiểu một vài cách dùng nhiều extensions để filter tập tin.Tình huống chúng ta sẽ có một thư mục Files trong ổ D: chứa danh sách 6 tập tin với nhiều loại extension như bên dưới:

D:\Files\file1.txt
D:\Files\file2.html
D:\Files\file3.xlsx
D:\Files\file4.docx
D:\Files\file5.csv
D:\Files\file6.pdf

Bây giờ chúng ta sẽ đi sâu vào từng cách cụ thể như sau:

CÁCH 1:

public void GetFilesByFilter1()
{
    txtInfo.Text = "Before filter" + Environment.NewLine;
    string[] files = Directory.GetFiles(@"D:\Files");
    foreach (string file in files)
    {
        txtInfo.Text += file + Environment.NewLine;
    }

    /* Using LinQ to filter by extention */
    string[] fileExtention = { ".html", ".txt", ".csv" };
    txtInfo.Text += "After filter" + Environment.NewLine;
    var filteredFiles = files.Where(f => fileExtention.Any(e => f.EndsWith(e)));
    foreach (var file in filteredFiles)
    {
        txtInfo.Text += file + Environment.NewLine;
    }
}

=> Kết quả thu được như sau:

Before filter
D:\Files\file1.txt
D:\Files\file2.html
D:\Files\file3.xlsx
D:\Files\file4.docx
D:\Files\file5.csv
D:\Files\file6.pdf
After filter
D:\Files\file1.txt
D:\Files\file2.html
D:\Files\file5.csv

CÁCH 2:

public void GetFilesByFilter2()
{
    IEnumerable filteredFiles = new List();
    string[] filters = { "*.html", "*.xlsx", "*.xml" };
    foreach (string filter in filters)
    {
        filteredFiles = filteredFiles.Concat(Directory.GetFiles(@"D:\Files", filter).AsEnumerable());
    }

    /* Get Files by filter list */
    foreach (var file in filteredFiles)
    {
        txtInfo.Text += file + Environment.NewLine;
    }
}

=> Kết quả thu được như sau:

D:\Files\file2.html
D:\Files\file3.xlsx

CÁCH 3:

public void GetFilesByFilter3()
{
    string extension1 = ".html";
    string extension2 = ".txt";
    var filteredFiles = Directory.GetFiles(@"D:\Files").Where(f=>f.Contains(extension1) || f.Contains(extension2));
    foreach (var file in filteredFiles)
    {
        txtInfo.Text += file + Environment.NewLine;
    }
}

=> Kết quả thu được như sau:

D:\Files\file1.txt
D:\Files\file2.html

CÁCH 4:

public void GetFilesByFilter4()
{
    string filters = "*.docx|*.xlsx|*.csv";
    var filteredFiles = filters.Split('|').SelectMany(filter => Directory.GetFiles(@"D:\Files", filter, SearchOption.AllDirectories)).ToList();
    foreach (var file in filteredFiles)
    {
        txtInfo.Text += file + Environment.NewLine;
    }
}

=> Kết quả thu được như sau:

D:\Files\file4.docx
D:\Files\file3.xlsx
D:\Files\file5.csv

CODE HOÀN CHỈNH:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace WinFormsApp
{
    public partial class FormMain : Form
    {
        public FormMain()
        {
            InitializeComponent();
            txtInfo.Text += "The first way: " + Environment.NewLine;
            GetFilesByFilter1();
            txtInfo.Text += Environment.NewLine + "The second way: " + Environment.NewLine;
            GetFilesByFilter2();
            txtInfo.Text += Environment.NewLine + "The third way: " + Environment.NewLine;
            GetFilesByFilter3();
            txtInfo.Text += Environment.NewLine + "The fourth way: " + Environment.NewLine;
            GetFilesByFilter4();
        }

        public void GetFilesByFilter1()
        {
            txtInfo.Text = "Before filter" + Environment.NewLine;
            string[] files = Directory.GetFiles(@"D:\Files");
            foreach (string file in files)
            {
                txtInfo.Text += file + Environment.NewLine;
            }

            /* Using LinQ to filter by extention */
            string[] fileExtention = { ".html", ".txt", ".csv" };
            txtInfo.Text += "After filter" + Environment.NewLine;
            var filteredFiles = files.Where(f => fileExtention.Any(e => f.EndsWith(e)));
            foreach (var file in filteredFiles)
            {
                txtInfo.Text += file + Environment.NewLine;
            }
        }

        public void GetFilesByFilter2()
        {
            IEnumerable filteredFiles = new List();
            string[] filters = { "*.html", "*.xlsx", "*.xml" };
            foreach (string filter in filters)
            {
                filteredFiles = filteredFiles.Concat(Directory.GetFiles(@"D:\Files", filter).AsEnumerable());
            }

            /* Get Files by filter list */
            foreach (var file in filteredFiles)
            {
                txtInfo.Text += file + Environment.NewLine;
            }
        }

        public void GetFilesByFilter3()
        {
            string extension1 = ".html";
            string extension2 = ".txt";
            var filteredFiles = Directory.GetFiles(@"D:\Files").Where(f=>f.Contains(extension1) || f.Contains(extension2));
            foreach (var file in filteredFiles)
            {
                txtInfo.Text += file + Environment.NewLine;
            }
        }

        public void GetFilesByFilter4()
        {
            string filters = "*.docx|*.xlsx|*.csv";
            var filteredFiles = filters.Split('|').SelectMany(filter => Directory.GetFiles(@"D:\Files", filter, SearchOption.AllDirectories)).ToList();
            foreach (var file in filteredFiles)
            {
                txtInfo.Text += file + Environment.NewLine;
            }
        }
    }
}

=> Kết quả thu được là:

Before filter
D:\Files\file1.txt
D:\Files\file2.html
D:\Files\file3.xlsx
D:\Files\file4.docx
D:\Files\file5.csv
D:\Files\file6.pdf
After filter
D:\Files\file1.txt
D:\Files\file2.html
D:\Files\file5.csv
The second way:
D:\Files\file2.html
D:\Files\file3.xlsx
The third way:
D:\Files\file1.txt
D:\Files\file2.html
The fourth way:
D:\Files\file4.docx
D:\Files\file3.xlsx
D:\Files\file5.csv

Chúc thành công!