重新想象 Windows 8 Store Apps (25) 选取器: 文件选取窗口, 文件夹选取窗口, 文件保存窗口

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重新想象 Windows 8 Store Apps (25) - 选取器: 文件选取窗口, 文件夹选取窗口, 文件保存窗口

作者：webabcd


介绍
重新想象 Windows 8 Store Apps 之 选取器

• FileOpenPicker - 选择一个文件或多个文件
• FolderPicker - 选择一个文件夹
• FileSavePicker - 保存文件到指定路径

示例
1、演示如何通过 FileOpenPicker 选择一个文件或多个文件
Picker/FileOpenPickerDemo.xaml

<Page
    x:Class="XamlDemo.Picker.FileOpenPickerDemo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Picker"
    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="btnPickFile" Content="pick a file" Click="btnPickFile_Click_1" Margin="0 10 0 0" />

            <Button Name="btnPickFiles" Content="pick multiple files" Click="btnPickFiles_Click_1" Margin="0 10 0 0" />

        </StackPanel>
    </Grid>
</Page>

Picker/FileOpenPickerDemo.xaml.cs

/*
 * 演示如何通过 FileOpenPicker 选择一个文件或多个文件
 * 
 * FileOpenPicker - 文件选择窗口
 *     ViewMode - 文件选择窗口的视图模式，Windows.Storage.Pickers.PickerViewMode 枚举（List 或 Thumbnail）
 *     SuggestedStartLocation - 文件选择窗口所显示的初始路径，Windows.Storage.Pickers.PickerLocationId 枚举
 *         DocumentsLibrary, ComputerFolder, Desktop,, Downloads, HomeGroup, MusicLibrary, PicturesLibrary，VideosLibrary
 *     FileTypeFilter - 允许显示在文件选择窗口的文件类型集合
 *     CommitButtonText - 文件选择窗口的提交按钮的显示文本，此按钮默认显示的文本为“打开”
 *     PickSingleFileAsync() -  弹出文件选择窗口，以让用户选择一个文件
 *     PickMultipleFilesAsync() - 弹出文件选择窗口，以让用户选择多个文件
 */

using System;
using System.Collections.Generic;
using Windows.Storage;
using Windows.Storage.AccessCache;
using Windows.Storage.Pickers;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace XamlDemo.Picker
{
    public sealed partial class FileOpenPickerDemo : Page
    {
        public FileOpenPickerDemo()
        {
            this.InitializeComponent();
        }

        private async void btnPickFile_Click_1(object sender, RoutedEventArgs e)
        {
            if (XamlDemo.Common.Helper.EnsureUnsnapped())
            {
                // 选择一个文件
                FileOpenPicker openPicker = new FileOpenPicker();
                openPicker.CommitButtonText = "选中此文件";
                openPicker.ViewMode = PickerViewMode.Thumbnail;
                openPicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
                openPicker.FileTypeFilter.Add(".jpg");
                openPicker.FileTypeFilter.Add(".gif");
                openPicker.FileTypeFilter.Add(".png");

                // 弹出文件选择窗口
                StorageFile file = await openPicker.PickSingleFileAsync(); // 用户在“文件选择窗口”中完成操作后，会返回对应的 StorageFile 对象
                if (file != null)
                {
                    lblMsg.Text = "选中文件: " + file.Name;
                }
                else
                {
                    lblMsg.Text = "取消了";
                }
            }
        }

        private async  void btnPickFiles_Click_1(object sender, RoutedEventArgs e)
        {
            if (XamlDemo.Common.Helper.EnsureUnsnapped())
            {
                // 选择多个文件
                FileOpenPicker openPicker = new FileOpenPicker();
                openPicker.ViewMode = PickerViewMode.List;
                openPicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
                openPicker.FileTypeFilter.Add("*");

                // 弹出文件选择窗口
                IReadOnlyList<StorageFile> files = await openPicker.PickMultipleFilesAsync(); // 用户在“文件选择窗口”中完成操作后，会返回对应的 StorageFile 对象
                if (files.Count > 0)
                {
                    lblMsg.Text = "选中文件: ";
                    lblMsg.Text += Environment.NewLine;
                    foreach (StorageFile file in files)
                    {
                        lblMsg.Text += (file.Name);
                        lblMsg.Text += Environment.NewLine;
                    }
                }
                else
                {
                    lblMsg.Text = "取消了";
                }
            }
        }
    }
}

2、演示如何通过 FolderPicker 选择一个文件夹
Picker/FolderPickerDemo.xaml

<Page
    x:Class="XamlDemo.Picker.FolderPickerDemo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Picker"
    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="btnPickFolder" Content="pick a folder" Click="btnPickFolder_Click_1" Margin="0 10 0 0 " />

        </StackPanel>
    </Grid>
</Page>

Picker/FolderPickerDemo.xaml.cs

/*
 * 演示如何通过 FolderPicker 选择一个文件夹
 * 
 * FolderPicker - 文件夹选择窗口
 *     ViewMode - 文件夹选择窗口的视图模式，Windows.Storage.Pickers.PickerViewMode 枚举（List 或 Thumbnail）
 *     SuggestedStartLocation - 文件夹选择窗口所显示的初始路径，Windows.Storage.Pickers.PickerLocationId 枚举
 *         DocumentsLibrary, ComputerFolder, Desktop,, Downloads, HomeGroup, MusicLibrary, PicturesLibrary，VideosLibrary
 *     FileTypeFilter - 允许显示在文件夹选择窗口的文件类型集合（只能显示符合要求的文件，但是无法选中）
 *     CommitButtonText - 文件夹选择窗口的提交按钮的显示文本，此按钮默认显示的文本为“选择这个文件夹”
 *     PickSingleFolderAsync() - 弹出文件夹选择窗口，以让用户选择一个文件夹
 */

using System;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace XamlDemo.Picker
{
    public sealed partial class FolderPickerDemo : Page
    {
        public FolderPickerDemo()
        {
            this.InitializeComponent();
        }

        private async void btnPickFolder_Click_1(object sender, RoutedEventArgs e)
        {
            if (XamlDemo.Common.Helper.EnsureUnsnapped())
            {
                // 选择一个文件夹
                FolderPicker folderPicker = new FolderPicker();
                folderPicker.SuggestedStartLocation = PickerLocationId.Desktop;
                folderPicker.FileTypeFilter.Add(".docx");
                folderPicker.FileTypeFilter.Add(".xlsx");
                folderPicker.FileTypeFilter.Add(".pptx");

                // 弹出文件夹选择窗口
                StorageFolder folder = await folderPicker.PickSingleFolderAsync(); // 用户在“文件夹选择窗口”中完成操作后，会返回对应的 StorageFolder 对象
                if (folder != null)
                {
                    lblMsg.Text = "选中文件夹: " + folder.Name;
                }
                else
                {
                    lblMsg.Text = "取消了";
                }
            }
        }
    }
}

3、演示如何通过 FileSavePicker 保存文件到指定路径
Picker/FileSavePickerDemo.xaml

<Page
    x:Class="XamlDemo.Picker.FileSavePickerDemo"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:XamlDemo.Pikcer"
    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="btnSaveFile" Content="save a file" Click="btnSaveFile_Click_1" Margin="0 10 0 0" />

        </StackPanel>
    </Grid>
</Page>

Picker/FileSavePickerDemo.xaml.cs

/*
 * 演示如何通过 FileSavePicker 保存文件到指定路径
 * 
 * FileSavePicker - 文件保存窗口
 *     SuggestedStartLocation - 文件保存窗口所显示的初始路径，Windows.Storage.Pickers.PickerLocationId 枚举
 *         DocumentsLibrary, ComputerFolder, Desktop,, Downloads, HomeGroup, MusicLibrary, PicturesLibrary，VideosLibrary
 *     SuggestedFileName - 需要保存的文件的默认文件名
 *     SuggestedSaveFile - 需要保存的文件的默认 StorageFile 对象
 *     FileTypeChoices - 可保存的扩展名集合
 *     DefaultFileExtension - 默认扩展名
 *     CommitButtonText - 文件保存窗口的提交按钮的显示文本，此按钮默认显示的文本为“保存”
 *     PickSaveFileAsync() - 弹出文件保存窗口，以让用户保存文件
 */

using System;
using System.Collections.Generic;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.Storage.Provider;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace XamlDemo.Picker
{
    public sealed partial class FileSavePickerDemo : Page
    {
        public FileSavePickerDemo()
        {
            this.InitializeComponent();
        }

        private async void btnSaveFile_Click_1(object sender, RoutedEventArgs e)
        {
            if (XamlDemo.Common.Helper.EnsureUnsnapped())
            {
                FileSavePicker savePicker = new FileSavePicker();
                savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;

                // 在扩展名选择框中将会显示：文本(.txt)
                savePicker.FileTypeChoices.Add("文本", new List<string>() { ".txt" });
                savePicker.SuggestedFileName = "webabcdFileSavePicker";

                // 弹出文件保存窗口
                StorageFile file = await savePicker.PickSaveFileAsync(); // 用户在“文件保存窗口”中完成操作后，会返回对应的 StorageFile 对象
                if (file != null)
                {
                    /*
                     * 运行到此，只是在目标地址创建了一个没有任何内容的空白文件而已，接下来开始向文件写入内容
                     */

                    // 告诉 Windows ，从此时开始要防止其它程序更新指定的文件
                    CachedFileManager.DeferUpdates(file);

                    // 将指定的内容保存到指定的文件
                    string textContent = "I am webabcd";
                    await FileIO.WriteTextAsync(file, textContent);

                    // 告诉 Windows ，从此时开始允许其它程序更新指定的文件
                    FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file);
                    if (status == FileUpdateStatus.Complete)
                    {
                        lblMsg.Text = "文件 " + file.Name + " 保存成功";
                    }

                    lblMsg.Text += Environment.NewLine;
                    lblMsg.Text += "FileUpdateStatus: " + status.ToString();
                }
                else
                {
                    lblMsg.Text = "取消了";
                }
            }
        }
    }
}

OK
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