frmfile.cs

移动设备的 LINQ 编程介绍 .NET Compact Framework 版 LINQ 的特性

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

namespace Demo1___LinqToObjects
{
	public partial class FrmFile : Form
	{
		public FrmFile()
		{
			InitializeComponent();
		}

		private void mniSearchFileQuery_Click(object sender, EventArgs e)
		{
			Cursor.Current = Cursors.WaitCursor;

			string startFolder = @"\Windows\";
			IEnumerable<FileInfo> fileList = GetFiles(startFolder);

			IEnumerable<FileInfo> fileQuery =
				from file in fileList
				where file.Extension == ".wav"
				orderby file.Name
				select file;

			listBox1.Items.Clear();
			listBox1.Items.Add("<<Query Syntax>>");
			foreach (var name in fileQuery)
			{
				listBox1.Items.Add(name.FullName);
			}

			var newestFile =
				(from file in fileQuery
				 orderby file.CreationTime
				 select new { file.FullName, file.CreationTime })
				.Last();

			listBox1.Items.Add("");
			listBox1.Items.Add("Newest .wav File: " + newestFile.FullName);
			listBox1.Items.Add("Creation time: " + newestFile.CreationTime);

			Cursor.Current = Cursors.Default;
		}

		private void mniSearchFileMethod_Click(object sender, EventArgs e)
		{
			Cursor.Current = Cursors.WaitCursor;

			string startFolder = @"\Windows\";
			IEnumerable<FileInfo> fileList = GetFiles(startFolder);

			IEnumerable<FileInfo> fileQuery = 
				fileList.Where(p => p.Extension == ".wav")
				.OrderBy(p => p.Name);

			listBox1.Items.Clear();
			listBox1.Items.Add("<<Method Syntax>>");
			foreach (var name in fileQuery)
			{
				listBox1.Items.Add(name.FullName);
			}

			var newestFile = 
				fileQuery.OrderBy(p => p.CreationTime)
				.Select(p => new { p.FullName, p.CreationTime }).Last();

			listBox1.Items.Add("");
			listBox1.Items.Add("Newest .wav File: " + newestFile.FullName);
			listBox1.Items.Add("Creation time: " + newestFile.CreationTime);

			Cursor.Current = Cursors.Default;
		}

		private IEnumerable<FileInfo> GetFiles(string path)
		{
			if (!Directory.Exists(path))
				throw new DirectoryNotFoundException();

			DirectoryInfo di = new DirectoryInfo(path);
			FileInfo[] files = di.GetFiles("*.*");
			return files;
		}

	}
}