Windows Phone 8 - 4 Files and Storage

transcript

Oliver Scheer

Senior Technical Evangelist

Microsoft Deutschland

http://the-oliver.com

Files and Storage in Windows Phone 8

04/12/20232

• WP7.1IsolatedStorage and

IsolatedStorageSettings APIs

• Local Storage and Isolated Storage

• Windown Phone Runtime

Windows.Storage programming

AgendaIn This Session…

Special FoldersShared/Media

Shared/ShellContent

Shared/Transfers

Exploring the local folder with ISET

Using Removable SD cards

04/12/2023Microsoft confidential3

• Local Database• No change from WP 7.1 • See • http://channel9.msdn.com/Series/Mango-Jump-Start/Mango-Jump-Start-0

8a-Application-Data-Storage-on-Windows-Phone--

Part-1 • http://

channel9.msdn.com/Series/Mango-Jump-Start/Mango-Jump-Start-08b-Application-Data-Storage-on-Windows-Phone-Part-2

• SQLite database (native only)

Not Covered in this Module…

Persistent Storage in Windows Phone 8

Local Data Storage: Overview

Package Manager installs all app files into the Installation Folder Read-only access from

app Read-only reference

database

Apps store data in Local Folder Settings and properties

in the app dictionary Unstructured data in

Isolated Storage files Structured data in

database files

ApplicationSettings File

App Creates/Managesfiles and settings

ApplicationFiles

Local FolderWP7.1:

“Isolated Storage”

Creates root folder

sandboxed to App

Package Manager

Installation Folder

WP7.1: “App Data”

WP8 Storage APIs or

WP7 Isolated Storage APIs

Install

Database file

DB DatabaseFile (r/o)

File Type/ API Installation Folder

Local Folder Example

Local Database data context

appdata:/ isostore:/ MyDataContext db = new MyDataContext ("isostore:/mydb.sdf")

Files access using WP7.1 Isolated Storage API

not supported

StorageFile and StorageFolder APIs

var isf = IsolatedStorageFile.GetUserStoreForApplication()

File access using Windows.Storage API via URIs

ms-appx:///ms-appdata:///local/

var file = await Windows.StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appdata:///local/AppConfigSettings.xml"));

File access using Windows.Storage API via StorageFolder references

Windows.ApplicationModel.Package.Current.InstalledLocation

Windows.Storage.ApplicationData.Current.LocalFolder

var localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;

Windows.Storage.StorageFile storageFile = await localFolder.GetFileAsync("CaptainsLog.store");

Different Methods For Addressing Storage Locations

• Three ways of getting a reference to the same file:// WP7.1 IsolatedStorage APIs

var isf = IsolatedStorageFile.GetUserStoreForApplication();

IsolatedStorageFileStream fs = new IsolatedStorageFileStream("CaptainsLog.store", FileMode.Open, isf));

// WP8 Storage APIs using URI

StorageFile storageFile = await Windows.Storage.StorageFile.GetFileFromApplicationUriAsync(

new Uri("ms-appdata:///local/CaptainsLog.store "));

// WP8 Storage APIs

Windows.Storage.StorageFolder localFolder = Windows.Storage.ApplicationData.Current.LocalFolder;

Windows.Storage.StorageFile storageFile = await localFolder.GetFileAsync("CaptainsLog.store");

WP8 File Access Alternatives

Storing Data using WP7.1 Isolated Storage APIs

Isolated Storage Classes• The IsolatedStorage classes are all in the System.IO.IsolatedStorage

namespace

• IsolatedStorageFile

• Represents an isolated storage area containing files and directories

• IsolatedFileStream

• Exposes a file stream access to a file stored within isolated storage

• IsolatedStorageSettings

• Dictionary<(Of <(TKey, TValue>)>) that stores key-value pairs

in isolated storage

Saving Data

private void saveGameToIsolatedStorage(string message){ using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication()) { using (IsolatedStorageFileStream rawStream = isf.CreateFile("MyFile.store")) { StreamWriter writer = new StreamWriter(rawStream); writer.WriteLine(message); // save the message writer.Close(); } }}

Loading Data

private string loadString(){ string result = null; using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication()) { if (isf.FileExists("Myfile.store") { using (IsolatedStorageFileStream rawStream = isf.OpenFile(filename, System.IO.FileMode.Open)) { StreamReader reader = new StreamReader(rawStream); result = reader.ReadLine(); reader.Close(); } } } return result;}

Demo 1: Using Isolated Storage

Application Settings

• If you just want to store setting information•Username = “Fred”• TextColor = “Green”

• ..you can use the ApplicationSettings object in Isolated Storage

• You use this as you would a dictionary

• You then write the object to persistent storage

Saving Data in Settings

• The storage works as a dictionary

• But you have to remember to call Save when you have finished adding keys

void saveString(string message, string name){ IsolatedStorageSettings.ApplicationSettings[name] = message;

IsolatedStorageSettings.ApplicationSettings.Save();}

Loading from Settings

• Test for the key before you try to find it or you will get an exception thrown

string loadString(string name){ if (IsolatedStorageSettings.ApplicationSettings. Contains(name)) { return (string) IsolatedStorageSettings.ApplicationSettings[name]; } else return null;}

Demo 2: Using Settings Storage

04/12/2023

Using Windows Phone Runtime Storage

Windows.Storage Classes• Windown Phone Runtime storage classes are in the

Windows.Storage namespace

• StorageFolder

• Represents a storage area containing files and directories

• StorageFile

• Represents a file and provides methods for manipulating them

• Not supported on Windows Phone 8:

• ApplicationData.LocalSettings

• Use custom file or IsolatedStorageSettings

Saving Data – Using StorageFolder

using System.IO;using Windows.Storage;…

private async void saveToLocalFolderAsync(string message){ // Get a reference to the Local Folder StorageFolder localFolder = ApplicationData.Current.LocalFolder;

// Create the file in the local folder, or if it already exists, just open it StorageFile storageFile = await localFolder.CreateFileAsync("Myfile.store", CreationCollisionOption.OpenIfExists);

Stream writeStream = await storageFile.OpenStreamForWriteAsync(); using (StreamWriter writer = new StreamWriter(writeStream)) { await writer.WriteAsync(logData); }}

Loading Data

using System.IO;using Windows.Storage;…

private async string loadStringAsync(){ string theData = string.Empty;

// Get a reference to the file in the Local Folder StorageFolder localFolder = ApplicationData.Current.LocalFolder; StorageFile storageFile = await localFolder.GetFileAsync(“Myfile.store"));

// Open it and read the contents Stream readStream = await storageFile.OpenStreamForReadAsync(); using (StreamReader reader = new StreamReader(readStream)) { theData = await reader.ReadToEndAsync(); }

return theData;}

Accessing Files Using ms-appdata:///local/ or ms-appx:/// // There's no FileExists method in WinRT, so have to try to open it and catch exception instead StorageFile storageFile = null; bool fileExists = false;

try { // Try to open file using URI storageFile = await StorageFile.GetFileFromApplicationUriAsync( new Uri("ms-appdata:///local/Myfile.store")); fileExists = true; } catch (FileNotFoundException) { fileExists = false; }

if (!fileExists) { await ApplicationData.Current.LocalFolder.CreateFileAsync("Myfile.store", CreationCollisionOption.FailIfExists); } ...

04/12/202322

•Windows Phone 8 implementation of Windows.Storage is a subset of Windows 8

WinRT• All data storage uses the LocalFolder (equivalent to WP7.1

IsolatedStorage)

•Not Supported:• Roaming Data Store: ApplicationData.Current.RoamingFolder• Temporary Data Store: ApplicationData.Current.TemporaryFolder• Local Settings: ApplicationData.Current.LocalSettings• Roaming Settings: ApplicationData.Current.RoamingSettings

Windows Phone 8 – Windows 8 CompatibilityOnly LocalFolder Supported

04/12/202323

• In Windows 8, you can programmatically load an Image file that you have

included in your app package into a XAML <Image> element using the URI

syntax, as follows:

RecipeImage.Source = new System.Windows.Media.Imaging.BitmapImage(

new Uri(@"ms-appx:///Images/french/French_1_600_C.jpg",

UriKind.RelativeOrAbsolute));

• In Windows Phone 8, you cannot use the URI syntax in this way. Continue to

use the relative path to the image, as in Windows Phone OS 7.1:

RecipeImage.Source =

System.Windows.Media.Imaging.BitmapImage("/Images/french/French_1_600_C.jpg");

Windows Phone 8 – Windows 8 CompatibilityProgrammatically Accessing Image Files

Demo 3: Using Windows.Storage

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Special Folders

Local Folder

• All read-write I/O operations

restricted to local folder

• Create a files and folder

structure hierarchy

• Use Isolated Settings storage

to store application settings

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Reserved Folders

• In addition to general data storage, the local

folder is used for the following special-use

scenarios:•Shared/Media - Apps can use this folder

to display album art in the Universal

Volume Control (UVC) while playing

background audio•Shared/ShellContent - Background

images for Tiles can be stored in isolated

storage, but must be located in this folder

or a subfolder of it •Shared/Transfers – Storage area used by

the Background File Transfer service

Data Serialization and Deserialization

Data Serialization

Data persistence and the app lifecycle

•App Launch•Deserialize data from Isolated Storage

•App being dormant/tombstoned• Serialize persistent data to Isolated Storage

•App being reactivated•Deserialize data from Isolated Storage

•App being terminated• Serialize persistent data to Isolated Storage

Not running

Launching

Running

Deactivated

/Closing

04/12/202330

Why Serialize?

• Serializers write the properties of a collection

of objects into a file so they can be stored in

persistent storage

•Deserializers reverse this: read data out of a

file and use it to ‘re-hydrate’ a collection of

in-memory objects

•Many different serializers are available:• XmlSerializer•DataContractSerializer•DataContractJsonSerializer• Third party…

Serialization using DataContractSerializer

public class MyDataSerializer<TheDataType> { public static async Task SaveObjectsAsync(TheDataType sourceData, String targetFileName) { StorageFile file = await ApplicationData.Current.LocalFolder.CreateFileAsync( targetFileName, CreationCollisionOption.ReplaceExisting); var outStream = await file.OpenStreamForWriteAsync();

DataContractSerializer serializer = new DataContractSerializer(typeof(TheDataType)); serializer.WriteObject(outStream, sourceData); await outStream.FlushAsync(); outStream.Close(); }

List<MyDataObjects> myObjects = ... await MyDataSerializer<List<MyDataObjects>>.SaveObjectsAsync(myObjects, "MySerializedObjects.xml");

• To use:

Deserialization using DataContractSerializer

public class MyDataSerializer<TheDataType> { public static async Task<TheDataType> RestoreObjectsAsync(string fileName) { StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(fileName); var inStream = await file.OpenStreamForReadAsync();

// Deserialize the objects. DataContractSerializer serializer = new DataContractSerializer(typeof(TheDataType)); TheDataType data = (TheDataType)serializer.ReadObject(inStream); inStream.Close();

return data; } ... }

List<MyDataObjects> myObjects = await MyDataSerializer<List<MyDataObjects>>.RestoreObjectsAsync("MySerializedObjects.xml");

• To use:

Demo 4: Serialization to Local Folder

Tools: Isolated Storage Explorer

Isolated Storage Explorer

• Isolated Storage Explorer is a command-line tool you use to list, copy, and

replace files and directories in Isolated Storage• Can be used on emulator or device• Can be used for applications that target Windows Phone OS 7.0, 7.1 and 8.0• at Program Files (x86)\Microsoft SDKs\Windows Phone\v8.0\Tools\

IsolatedStorageExplorerTool

• Syntax:

ISETool.exe <ts|rs|dir[:device-folder]> <xd|de> <Product GUID>

[<desktop-path>]

ts – Take snapshot

rs – Restore snapshot

dir – Lists the files or directories

xd – target the emulator

de – target device

Guid – ProductID from the WPAppManifest.xml file for the app

Desktop-path – directory on your computer where isolated storage files are written t o or copied from

Isolated Storage Explorer Example

Accessing SD Cards

04/12/2023

•Windows Phone 8 devices support SD cards

• App can read files stored on a storage card•Must declare the ID_CAP_REMOVABLE_STORAGE capability in the

application manifest file• Cannot write files - Access is Read Only• Can only access file types for which your app has registered a file

association in WMAppManifest.xml

External Storage (SD Card)

• You can only open files for which you have declared a File Association in

WMAppManifest.xml

• Edit WMAppManifest.xml using the XML editor, not the Manifest editor

• Add a FileTypeAssociation element inside the Extensions element• The Extensions element must follow immediately after the Tokens element• Note that the ContentType attribute on the FileType element is required

</SupportedFileTypes>

</FileTypeAssociation>

</Extensions>

Declare a File Association to WMAppManifest.xml

API DescriptionExternalStorageDevice

Represents an SD card. Use the ExternalStorageDeviceExternalStorageID() property to uniquely identify a card.

ExternalStorage.GetExternalStorageDevicesAsync()

Returns a collection of SD cards that are inserted in the phone. This collection will contain no more than one SD card.

ExternalStorageFolder Represents a folder on the SD card. Use the ExternalStorageFolderPath() property to access the folder later.

ExternalStorageFile Represents a file on the SD card. Use the ExternalStorageFilePath() property to access the file later.

ExternalStorageDeviceGetFileAsync() and ExternalStorageDeviceGetFolderAsync()

Obtain a file or folder directly from the external storage device object.

External Storage APIs

Best Practices

Quota Management

• There are no quotas on Windows Phone!

• Applications must make careful use of space•Use only is necessary• Be transparent about storage usage

•Manage application data•Delete temporary data and files when no longer required• Consider synchronizing or archiving data to the cloud to reduce device

storage

Serialization and Threads

• If your status information is a complex object you can easily save the object by

serializing it• Serialization may slow down the saving and loading of data

• You should consider the use of threading in this situation• Perform your loading and saving on a separate thread so that the application

stays responsive

The information herein is for informational purposes only an represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be

interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation.

MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Windows Phone 8 - 4 Files and Storage

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