图解使用win8api进行metro风格的程序开发二----使用文件选择器访问和保存文件

我们紧接着上篇,这篇将介绍如何使用文件选择器访问和保存文件-我是华丽的分割线-此示例演示用户如何使用文件选择器选择您的应用程序文件和文件夹，根据用户指定的名称，文件类型和文件保存的位置。这个示例使用 Windows.Storage.Pickers API。本篇将介绍如下四个方面:a)让用户选择一个文件b)让用户选择多个文件c)让用户选择一个文件夹d)让用户保存文件和指定的名称，文件类型和/或保存位置我们的创建的步骤如下: 1)为了组织文件方便,我们先建一个文件夹 FilePicker2)向文件夹中添加如下四个文件:PickAFolder.xaml,PickASinglePhoto.xaml,PickMultipleFiles.xaml,SaveAFile.xaml创建方式如图:3)此时的解决方案结构如下:4)向我们的 DataSource 添加导航所需要的信息修改我们的 SampleDataSource.cs 文件中的 SampleDataSource 类中的代码,代码如下: View Code public sealed class SampleDataSourceprivate static SampleDataSource _sampleDataSource = new SampleDataSource(); private ObservableCollection _allGroups = new ObservableCollection();public ObservableCollection AllGroupsget return this._allGroups; public static IEnumerable GetGroups(string uniqueId)if (!uniqueId.Equals(“AllGroups“) throw new ArgumentException(“Only AllGroups is supported as a collection of groups“);return _sampleDataSource.AllGroups;public static SampleDataGroup GetGroup(string uniqueId)/ Simple linear search is acceptable for small data setsvar matches = _sampleDataSource.AllGroups.Where(group) = group.UniqueId.Equals(uniqueId);if (matches.Count() = 1) return matches.First();return null;public static SampleDataItem GetItem(string uniqueId)/ Simple linear search is acceptable for small data setsvar matches = _sampleDataSource.AllGroups.SelectMany(group = group.Items).Where(item) = item.UniqueId.Equals(uniqueId);if (matches.Count() = 1) return matches.First();return null;public SampleDataSource()var group1 = new SampleDataGroup(“FilePicker“,“Use Windows.Storage.Pickers API“,“Access and save files using the file picker“,“Assets/FilePicker.jpg“,“);group1.Items.Add(new SampleDataItem(“FilePicker-PickASinglePhoto“,“Pick a single photo“,“only one file can selected,file type is jpg,jpeg,png“,“Assets/FilePicker.jpg“,“only one file can selected “,“,group1,typeof(PickASinglePhoto);group1.Items.Add(new SampleDataItem(“FilePicker-PickMultipleFiles“,“Pick multiple files“,“you can pick multiple files“,“Assets/FilePicker.jpg“,“pick multiple files“,“,group1,typeof(PickMultipleFiles);group1.Items.Add(new SampleDataItem(“FilePicker-PickAFolder“,“Pick a folder“,“you can pick a folder“,“Assets/FilePicker.jpg“,“Pick a folder“,“,group1,typeof(PickAFolder);group1.Items.Add(new SampleDataItem(“FilePicker-SaveAFile“,“Save a file“,“you can save a file“,“Assets/FilePicker.jpg“,“Save a file“,“,group1,typeof(SaveAFile);this.AllGroups.Add(group1);5)我们的导航这样就做好了,效果图 :点击,出现如下图片:6)我们开始我们的任务:让用户选择一个文件使用的 FileOpenPicker 的 PickSingleFileAsync 方法来调用一个文件选择器窗口，让用户选择一个单一的文件。修改 PickASinglePhoto.xaml 的代码:View Code Prompt the user to pick a single photo.修改后台代码:View Code public sealed partial class PickASinglePhoto : Pagepublic PickASinglePhoto()this.InitializeComponent();PickAFileButton.Click += new RoutedEventHandler(PickAFileButton_Click);/ / Invoked when this page is about to be displayed in a Frame./ / Event data that describes how this page was reached. The Parameter/ property is typically used to configure the tected override void OnNavigatedTo(NavigationEventArgs e)private async void PickAFileButton_Click(object sender, RoutedEventArgs e)FileOpenPicker openPicker = new FileOpenPicker();/设置呈现视图模式为缩略图openPicker.ViewMode = PickerViewMode.Thumbnail;/设置文件选择器打开时的起始位置，这里设置为图片库openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;/添加文件过滤器openPicker.FileTypeFilter.Add(“.jpg“);openPicker.FileTypeFilter.Add(“.jpeg“);openPicker.FileTypeFilter.Add(“.png“);/异步调用 PickSingleFileAsyncStorageFile file = await openPicker.PickSingleFileAsync();if (file != null)OutputTextBlock.Text = “Picked photo: “ + file.Name;elseOutputTextBlock.Text = “Operation cancelled.“;效果图如下:7)让用户选择多个文件使用的 FileOpenPicker 的 PickMultipleFilesAsync 方法来调用一个文件选择器窗口，让用户选择多个文件。修改我们的 PickMultipleFiles.xaml代码如下:View Code Prompt the user to pick one or more files.后台代码:View Code public sealed partial class PickMultipleFiles : Pagepublic PickMultipleFiles()this.InitializeComponent();PickFilesButton.Click += new RoutedEventHandler(PickFilesButton_Click);/ / Invoked when this page is about to be displayed in a Frame./ / Event data that describes how this page was reached. The Parameter/ property is typically used to configure the tected override void OnNavigatedTo(NavigationEventArgs e)private async void PickFilesButton_Click(object sender, RoutedEventArgs e)FileOpenPicker openPicker = new FileOpenPicker();/设置呈现视图模式为列表openPicker.ViewMode = PickerViewMode.List;/设置文件选择器打开时的起始位置，这里设置为文档库openPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;/不过滤任何类型openPicker.FileTypeFilter.Add(“*“);/调用 PickMultipleFilesAsync 获得选择文件列表IReadOnlyList files = await openPicker.PickMultipleFilesAsync();if (files.Count 0)StringBuilder output = new StringBuilder(“Picked files:n“);foreach (StorageFile file in files)output.Append(file.Name + “n“);OutputTextBlock.Text = output.ToString();elseOutputTextBlock.Text = “Operation cancelled.“; 效果图:8)让用户选择一个文件夹使用的 FolderPicker 的 PickSingleFolderAsync 方法来调用一个文件选择器窗口，让用户选择一个文件夹。修改我们的 PickAFolder.xaml 的 xmal 代码:View Code Prompt the user to pick a folder so its contents can be accessed later.修改后台代码:View Code public sealed partial class PickAFolder : Pagepublic PickAFolder()this.InitializeComponent();PickFolderButton.Click += new RoutedEventHandler(PickFolderButton_Click);/ / Invoked when this page is about to be displayed in a Frame./ / Event data that describes how this page was reached. The Parameter/ property is typically used to configure the tected override void OnNavigatedTo(NavigationEventArgs e)private async void PickFolderButton_Click(object sender, RoutedEventArgs e)FolderPicker folderPicker = new FolderPicker();folderPicker.SuggestedStartLocation = PickerLocationId.Desktop;folderPicker.FileTypeFilter.Add(“.jpg“);/调用 PickSingleFolderAsync 选择文件夹StorageFolder folder = await folderPicker.PickSingleFolderAsync();if (folder != null)/ 提供对列表的访问，使用该列表，应用程序可以跟踪最近访问的文件或位置和将来要存储的文件或位置StorageApplicationPermissions.FutureAccessList.AddOrReplace(“PickedFolderToken“, folder);OutputTextBlock.Text = “Picked folder: “ + folder.Name;elseOutputTextBlock.Text = “Operation cancelled.“;效果图:9)让用户保存文件和指定的名称，文件类型和/或保存位置使用的 FileSavePicker 的 PickSaveFileAsync 方法来调用一个文件选择器窗口，让用户保存文件。修改我们的 SaveAFile.xaml 的代码:View Code Prompt the user to save a file.修改后台代码:View Code public sealed partial class SaveAFile : Pagepublic SaveAFile()this.InitializeComponent();SaveFileButton.Click += new RoutedEventHandler(SaveFileButton_Click);/ / Invoked when this page is about to be displayed in a Frame./ / Event data that describes how this page was reached. The Parameter/ property is typically used to configure the tected override void OnNavigatedTo(NavigationEventArgs e)private async void SaveFileButton_Click(object sender, RoutedEventArgs e)FileSavePicker savePicker = new FileSavePicker();savePicke