在本文中，我想谈论移动设备上的文件。我们将创建文件，在文件资源管理器中打开它们，然后按类型过滤。让我们走。
最重要的是，让我们创建一个简单的毛伊岛项目：
dotnet new maui -n FilePickAndSaveSample
让我们转到“mainpage.xamlâ文件并删除verticalstacklayout block中的所有元素。不需要我们。 >
下一步，您需要安装“ communityToolkit.maui套件。完成之后，应该注册它。为此，请访问“ mauiprogram.cs”并添加此代码：
var builder = MauiApp.CreateBuilder();
builder
.UseMauiApp<App>()
.UseMauiCommunityToolkit()
.ConfigureFonts(fonts =>
{
fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
});
接下来，让我们将保存文件保存到我们的移动设备。让我们回到我们的“mainpage.xamlâ文件，添加几个项目：按钮和标签。
<Label
HorizontalOptions="Center"
HorizontalTextAlignment="Center"
LineBreakMode="WordWrap"
Text="The FileSaver provides the ability to select target folder and save files to the file system." />
<Button
Clicked="SaveFile_Clicked"
HorizontalOptions="Center"
Text="Save file" />
然后转到“ mainpage.xaml.cs”文件，然后创建两个处理程序：
private async void SaveFile_Clicked(object sender, EventArgs e)
{
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
CancellationToken cancellationToken = cancellationTokenSource.Token;
try
{
await SaveFile(cancellationToken);
}
catch (OperationCanceledException)
{
throw new OperationCanceledException("It was cancelled");
}
}
，也让我们创建一个单独的保存文件方法：
private async Task SaveFile(CancellationToken cancellationToken)
{
using var stream = new MemoryStream(Encoding.Default.GetBytes("Hello from the Dev.to Community!"));
var fileName = Application.Current?.MainPage?.DisplayPromptAsync("FileSaver", "Choose filename") ?? Task.FromResult("untitled.txt");
var fileSaverResult = await FileSaver.Default.SaveAsync(await fileName, stream, cancellationToken);
if (fileSaverResult.IsSuccessful)
{
await Toast.Make($"The file was saved successfully to location: {fileSaverResult.FilePath}").Show(cancellationToken);
}
else
{
await Toast.Make($"The file was not saved successfully with error: {fileSaverResult.Exception.Message}").Show(cancellationToken);
}
}
但不是全部。让我们回到“ mauiprogram.cs”文件和注册服务，只需添加此行：
builder.Services.AddSingleton(FileSaver.Default);
顺便说一句。您可能如何注意到我们注入了Service FileSaver静态方式，但是您可以使用另外两种方式：注入构造函数或创建新实例。为了方便，我将使用静态注射。
，但是无论如何，让我们检查一下。
单击“保存txt”按钮：
键入“plain_text.txtâ和点击OK。此外，选择本地存储并进入其中。重复相同的doc_text.docâ和“ pic.jpeg”的过程
现在，让我们为Pick文件夹创建服务。这是与保存文件相似的所有内容。首先，转到“ mauipragram.cs”文件并注册新服务：
builder.Services.AddSingleton(FolderPicker.Default);
，还添加lable和按钮：
<Label
HorizontalOptions="Center"
HorizontalTextAlignment="Center"
LineBreakMode="WordWrap"
Text="FolderPicker allows you to pick a folder from the device" />
<Button
Clicked="PickFolder_Clicked"
HorizontalOptions="Center"
Text="Pick Folder" />
还需要处理程序和方法：
private async void PickFolder_Clicked(object sender, EventArgs e)
{
CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
CancellationToken cancellationToken = cancellationTokenSource.Token;
try
{
await PickFolder(cancellationToken);
}
catch (OperationCanceledException)
{
throw new OperationCanceledException("It was cancelled");
}
}
private async Task PickFolder(CancellationToken cancellationToken)
{
var folderResult = await FolderPicker.PickAsync("DCIM", cancellationToken);
if (folderResult.IsSuccessful)
{
var filesCount = Directory.EnumerateFiles(folderResult.Folder.Path).Count();
await Toast.Make($"Folder picked: Name - {folderResult.Folder.Name}, Path - {folderResult.Folder.Path}, Files count - {filesCount}", ToastDuration.Long).Show(cancellationToken);
}
else
{
await Toast.Make($"Folder is not picked, {folderResult.Exception.Message}").Show(cancellationToken);
}
}
让我们退房：
单击“选择文件夹”，然后选择文件夹。如果再次点击按钮，您将处于与之前选择的同一文件夹。
和我想显示的最后一件事，是按类型进行选择的文件。让我们做并注册服务：
builder.Services.AddSingleton(FilePicker.Default);
添加lable和几个按钮：
<Label
HorizontalOptions="Center"
HorizontalTextAlignment="Center"
LineBreakMode="WordWrap"
Text="FilePicker allows you to pick a file from the device" />
<Button
Clicked="PickPhoto_Clicked"
HorizontalOptions="Center"
Text="Pick a Photo" />
<Button
Clicked="PickFile_Clicked"
HorizontalOptions="Center"
Text="Pick a File" />
<Label
FontSize="15"
HorizontalTextAlignment="Center"
x:Name="FileName" />
添加处理程序：
private async void PickPhoto_Clicked(object sender, EventArgs e)
{
FileResult result = await _filePicker.PickAsync(new PickOptions
{
PickerTitle = "Pick a Photo",
FileTypes = FilePickerFileType.Images
});
if (result == null) return;
FileName.Text = result.FileName;
}
private async void PickFile_Clicked(object sender, EventArgs e)
{
var customFileTypes = new FilePickerFileType(new Dictionary<DevicePlatform, IEnumerable<string>>
{
{
DevicePlatform.iOS, new[]
{
"com.microsoft.word.doc",
"public.plain-text",
"org.openxmlformats.wordprocessingml.document"
}
},
{
DevicePlatform.Android, new[]
{
"application/msword",
"text-plain",
"application/vnd.openxmlformats-officedocument.wordprocessingml.document"
}
},
{
DevicePlatform.WinUI, new[]
{
"doc","docx", "txt"
}
},
});
FileResult result = await _filePicker.PickAsync(new PickOptions
{
PickerTitle = "Pick a File",
FileTypes = customFileTypes
});
if (result == null) return;
FileName.Text = result.FileName;
}
现在我们可以退房。如果单击“选择照片”，则只能选择图片。
就是全部。资料来源：CLICK
快乐编码！
