重新想象 Windows 8 Store Apps (22) - 文件系统: 访问文件夹和文件, 通过 AQS 搜索本地文件
重新想象 Windows 8 Store Apps (22) - 文件系统: 访问文件夹和文件, 通过 AQS 搜索本地文件
作者:webabcd
介绍
重新想象 Windows 8 Store Apps 之 文件系统
- File Access - 访问文件夹和文件,以及获取文件的各种属性
- Folder Access - 遍历文件夹时的一些特殊操作
- Thumbnail Access - 获取文件的缩略图
- AQS - 通过 AQS(Advanced Query Syntax)搜索本地文件
示例
1、演示如何访问文件夹和文件,以及如何获取文件的各种属性
FileSystem/FileAccess.xaml
<Page x:Class="XamlDemo.FileSystem.FileAccess" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:XamlDemo.FileSystem" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <StackPanel Margin="120 0 0 0"> <TextBlock Name="lblMsg" FontSize="14.667" /> <ListBox Name="listBox" Width="400" Height="200" SelectionChanged="listBox_SelectionChanged_1" HorizontalAlignment="Left" Margin="0 10 0 0" /> </StackPanel> </Grid> </Page>
FileSystem/FileAccess.xaml.cs
/* * 演示如何访问文件夹和文件,以及如何获取文件的各种属性 * * StorageFolder - 文件夹操作类 * 获取文件夹相关属性、重命名、Create...、Get...等 * * StorageFile - 文件操作类 * 获取文件相关属性、重命名、Create...、Get...、Copy...、Move...、Delete...、Open...、Replace...等 * * 注:WinRT 中的关于存储操作的相关类都在 Windows.Storage 命名空间内 */ using System; using System.Collections.Generic; using Windows.Storage; using Windows.Storage.FileProperties; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Navigation; using System.Linq; namespace XamlDemo.FileSystem { public sealed partial class FileAccess : Page { public FileAccess() { this.InitializeComponent(); } protected async override void OnNavigatedTo(NavigationEventArgs e) { // 遍历“文档库”目录下的所有顶级文件(需要在 Package.appxmanifest 中选中“文档库”功能) StorageFolder storageFolder = KnownFolders.DocumentsLibrary; IReadOnlyList<StorageFile> files = await storageFolder.GetFilesAsync(); listBox.ItemsSource = files.Select(p => p.Name).ToList(); } private async void listBox_SelectionChanged_1(object sender, SelectionChangedEventArgs e) { // 获取用户选中的文件 string fileName = (string)listBox.SelectedItem; StorageFolder storageFolder = KnownFolders.DocumentsLibrary; StorageFile storageFile = await storageFolder.GetFileAsync(fileName); // 显示文件的各种属性 if (storageFile != null) { lblMsg.Text = "Name:" + storageFile.Name; lblMsg.Text += Environment.NewLine; lblMsg.Text += "FileType:" + storageFile.FileType; lblMsg.Text += Environment.NewLine; BasicProperties basicProperties = await storageFile.GetBasicPropertiesAsync(); lblMsg.Text += "Size:" + basicProperties.Size; lblMsg.Text += Environment.NewLine; lblMsg.Text += "DateModified:" + basicProperties.DateModified; lblMsg.Text += Environment.NewLine; /* * 获取文件的其它各种属性 * 详细属性列表请参见:http://msdn.microsoft.com/en-us/library/windows/desktop/ff521735(v=vs.85).aspx */ List<string> propertiesName = new List<string>(); propertiesName.Add("System.DateAccessed"); propertiesName.Add("System.DateCreated"); propertiesName.Add("System.FileOwner"); IDictionary<string, object> extraProperties = await storageFile.Properties.RetrievePropertiesAsync(propertiesName); lblMsg.Text += "System.DateAccessed:" + extraProperties["System.DateAccessed"]; lblMsg.Text += Environment.NewLine; lblMsg.Text += "System.DateCreated:" + extraProperties["System.DateCreated"]; lblMsg.Text += Environment.NewLine; lblMsg.Text += "System.FileOwner:" + extraProperties["System.FileOwner"]; } } } }
2、演示遍历文件夹时的一些特殊操作
FileSystem/FolderAccess.xaml
<Page x:Class="XamlDemo.FileSystem.FolderAccess" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:XamlDemo.FileSystem" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <StackPanel Margin="120 0 0 0"> <TextBlock Name="lblMsg" FontSize="14.667" /> <Button Name="btnGroupFile" Content="分组文件" Click="btnGroupFile_Click_1" Margin="0 10 0 0" /> <Button Name="btnPrefetchAPI" Content="从 Prefetch 中加载信息" Click="btnPrefetchAPI_Click_1" Margin="0 10 0 0" /> </StackPanel> </Grid> </Page>
FileSystem/FolderAccess.xaml.cs
/* * 演示遍历文件夹时的一些特殊操作 * 1、演示如何对 StorageFolder 中的内容做分组 * 2、演示如何通过文件扩展名过滤内容,以及如何从 Prefetch 中获取数据 * * StorageFolder - 文件夹操作类 * 获取文件夹相关属性、重命名、Create...、Get...等 * * StorageFile - 文件操作类 * 获取文件相关属性、重命名、Create...、Get...、Copy...、Move...、Delete...、Open...、Replace...等 * * 注:WinRT 中的关于存储操作的相关类都在 Windows.Storage 命名空间内 */ using System; using System.Collections.Generic; using Windows.Storage; using Windows.Storage.FileProperties; using Windows.Storage.Search; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Navigation; namespace XamlDemo.FileSystem { public sealed partial class FolderAccess : Page { public FolderAccess() { this.InitializeComponent(); } // 演示如何对 StorageFolder 中的内容做分组 private async void btnGroupFile_Click_1(object sender, Windows.UI.Xaml.RoutedEventArgs e) { lblMsg.Text = ""; StorageFolder picturesFolder = KnownFolders.PicturesLibrary; // 创建一个按月份分组的查询 QueryOptions queryOptions = new QueryOptions(CommonFolderQuery.GroupByMonth); // 对指定文件夹执行指定的文件夹查询,返回分组后的文件夹数据 StorageFolderQueryResult queryResult = picturesFolder.CreateFolderQueryWithOptions(queryOptions); IReadOnlyList<StorageFolder> folderList = await queryResult.GetFoldersAsync(); foreach (StorageFolder folder in folderList) // 这里的 floder 就是按月份分组后的月份文件夹(当然,物理上并没有月份文件夹) { IReadOnlyList<StorageFile> fileList = await folder.GetFilesAsync(); lblMsg.Text += folder.Name + " (" + fileList.Count + ")"; lblMsg.Text += Environment.NewLine; foreach (StorageFile file in fileList) // 月份文件夹内的文件 { lblMsg.Text += " " + file.Name; lblMsg.Text += Environment.NewLine; } } } // 演示如何通过文件扩展名过滤内容,以及如何从 Prefetch 中获取数据 private async void btnPrefetchAPI_Click_1(object sender, Windows.UI.Xaml.RoutedEventArgs e) { /* * Prefetch 是预读的文件信息,其在 C:\Windows\Prefetch 目录内,可以从中获取文件属性信息和文件缩略图,在访问大量文件的场景下可以提高效率 */ lblMsg.Text = ""; List<string> fileTypeFilter = new List<string>(); fileTypeFilter.Add(".jpg"); fileTypeFilter.Add(".png"); // 新建一个查询,指定需要查询的文件的扩展名 QueryOptions queryOptions = new QueryOptions(CommonFileQuery.OrderByName, fileTypeFilter); // 通过 QueryOptions.SetPropertyPrefetch() 来设置需要从 Prefetch 中获取的属性信息 List<string> propertyNames = new List<string>(); propertyNames.Add("System.FileOwner"); queryOptions.SetPropertyPrefetch(PropertyPrefetchOptions.ImageProperties, propertyNames); /* * 通过 QueryOptions.SetThumbnailPrefetch() 来设置需要从 Prefetch 中获取的缩略图 uint requestedSize = 190; ThumbnailMode thumbnailMode = ThumbnailMode.PicturesView; ThumbnailOptions thumbnailOptions = ThumbnailOptions.UseCurrentScale; queryOptions.SetThumbnailPrefetch(thumbnailMode, requestedSize, thumbnailOptions); */ // 对指定文件夹执行指定的文件查询,返回查询后的文件数据 StorageFileQueryResult queryResult = KnownFolders.PicturesLibrary.CreateFileQueryWithOptions(queryOptions); IReadOnlyList<StorageFile> fileList = await queryResult.GetFilesAsync(); foreach (StorageFile file in fileList) { lblMsg.Text += file.Name; // 文件名 // 获取图像属性 ImageProperties properties = await file.Properties.GetImagePropertiesAsync(); lblMsg.Text += "(" + properties.Width + "x" + properties.Height + ")"; // 获取其他属性(详细属性列表请参见:http://msdn.microsoft.com/en-us/library/windows/desktop/ff521735(v=vs.85).aspx) IDictionary<string, object> extraProperties = await file.Properties.RetrievePropertiesAsync(propertyNames); lblMsg.Text += "(" + extraProperties["System.FileOwner"] + ")"; // 获取缩略图 // StorageItemThumbnail thumbnail = await file.GetThumbnailAsync(thumbnailMode, requestedSize, thumbnailOptions); } } } }
3、演示如何获取文件的缩略图
FileSystem/ThumbnailAccess.xaml
<Page x:Class="XamlDemo.FileSystem.ThumbnailAccess" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="using:XamlDemo.FileSystem" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d"> <Grid Background="Transparent"> <ScrollViewer Margin="120 0 0 0"> <StackPanel> <Button Name="btnGetThumbnail" Content="获取文件的缩略图" Click="btnGetThumbnail_Click_1" /> <Image Name="img" Stretch="None" HorizontalAlignment="Left" Margin="0 10 0 0" /> <TextBlock Name="lblMsg" FontSize="14.667" Margin="0 10 0 0" /> </StackPanel> </ScrollViewer> </Grid> </Page>
FileSystem/ThumbnailAccess.xaml.cs
/* * 演示如何获取文件的缩略图 * * 获取指定文件或文件夹的缩略图,返回 StorageItemThumbnail 类型的数据 * StorageFile.GetThumbnailAsync(ThumbnailMode mode, uint requestedSize, ThumbnailOptions options) * StorageFolder.GetThumbnailAsync(ThumbnailMode mode, uint requestedSize, ThumbnailOptions options) * ThumbnailMode mode - 用于描述缩略图的目的,以使系统确定缩略图图像的调整方式(PicturesView, VideosView, MusicView, DocumentsView, ListView, SingleItem) * 关于 ThumbnailMode 的详细介绍参见:http://msdn.microsoft.com/en-us/library/windows/apps/hh465350.aspx * uint requestedSize - 期望尺寸的最长边长的大小 * ThumbnailOptions options - 检索和调整缩略图的行为(None, ReturnOnlyIfCached, ResizeThumbnail, UseCurrentScale) */ using System; using Windows.Storage; using Windows.Storage.FileProperties; using Windows.Storage.Pickers; using Windows.UI.Xaml; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Media.Imaging; namespace XamlDemo.FileSystem { public sealed partial class ThumbnailAccess : Page { public ThumbnailAccess() { this.InitializeComponent(); } private async void btnGetThumbnail_Click_1(object sender, RoutedEventArgs e) { if (XamlDemo.Common.Helper.EnsureUnsnapped()) { FileOpenPicker openPicker = new FileOpenPicker(); openPicker.FileTypeFilter.Add("*"); StorageFile file = await openPicker.PickSingleFileAsync(); if (file != null) { ThumbnailMode thumbnailMode = ThumbnailMode.PicturesView; ThumbnailOptions thumbnailOptions = ThumbnailOptions.UseCurrentScale; uint requestedSize = 200; using (StorageItemThumbnail thumbnail = await file.GetThumbnailAsync(thumbnailMode, requestedSize, thumbnailOptions)) { if (thumbnail != null) { BitmapImage bitmapImage = new BitmapImage(); bitmapImage.SetSource(thumbnail); img.Source = bitmapImage; lblMsg.Text = "file name: " + file.Name; lblMsg.Text += Environment.NewLine; lblMsg.Text += "requested size: " + requestedSize; lblMsg.Text += Environment.NewLine; lblMsg.Text += "returned size: " + thumbnail.OriginalWidth + "*" + thumbnail.OriginalHeight; } } } } } } }
4、演示如何通过 AQS - Advanced Query Syntax 搜索本地文件
FileSystem/AQS.xaml.cs
/* * 演示如何通过 AQS - Advanced Query Syntax 搜索本地文件 */ using System; using System.Collections.Generic; using Windows.Storage; using Windows.Storage.BulkAccess; using Windows.Storage.FileProperties; using Windows.Storage.Search; using Windows.UI.Xaml.Controls; using Windows.UI.Xaml.Navigation; namespace XamlDemo.FileSystem { public sealed partial class AQS : Page { public AQS() { this.InitializeComponent(); } protected async override void OnNavigatedTo(NavigationEventArgs e) { // 准备在“音乐库”中进行搜索(需要在 Package.appxmanifest 的“功能”中选中“音乐库”) StorageFolder musicFolder = KnownFolders.MusicLibrary; // 准备搜索所有类型的文件 List<string> fileTypeFilter = new List<string>(); fileTypeFilter.Add("*"); // 搜索的查询参数 QueryOptions queryOptions = new QueryOptions(CommonFileQuery.OrderByDate, fileTypeFilter); // 指定 AQS 字符串,参见 http://msdn.microsoft.com/zh-cn/library/windows/apps/aa965711.aspx queryOptions.UserSearchFilter = "五月天"; // 根据指定的参数创建一个查询 StorageFileQueryResult fileQuery = musicFolder.CreateFileQueryWithOptions(queryOptions); lblMsg.Text = "在音乐库中搜索“五月天”,结果如下:"; lblMsg.Text += Environment.NewLine; // 开始搜索,并返回检索到的文件列表 IReadOnlyList<StorageFile> files = await fileQuery.GetFilesAsync(); if (files.Count == 0) { lblMsg.Text += "什么都没搜到"; } else { foreach (StorageFile file in files) { lblMsg.Text += file.Name; lblMsg.Text += Environment.NewLine; } } // 关于 QueryOptions 的一些用法,更详细的 QueryOptions 的说明请参见 msdn queryOptions = new QueryOptions(); queryOptions.FolderDepth = FolderDepth.Deep; queryOptions.IndexerOption = IndexerOption.UseIndexerWhenAvailable; queryOptions.SortOrder.Clear(); var sortEntry = new SortEntry(); sortEntry.PropertyName = "System.FileName"; sortEntry.AscendingOrder = true; queryOptions.SortOrder.Add(sortEntry); fileQuery = KnownFolders.PicturesLibrary.CreateFileQueryWithOptions(queryOptions); } } }
OK
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