Windows Phone8开发入门（四）



Windows Phone 8文件和存储

 

WP7.1 IsolatedStorage和IsolatedStorageSetting是 APIs

 

“本地存储”和“独立存储”

读取文件的不同方式：

Local Database data context

Files acess using WP7.1 Isolated Storage API

Files access using Windows.Storage API via URIs

File access using Windows.Storage API via StorageFolder references

WP8文件访问的选择：

//WP7.1 IsolatedStorage APIs

Var isf=IsolatedStorageFile.GetUserStoreForApplication();

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

···

//WP8 Storage APIs using URI

StorageFile StorageFile=awaitWindowsd.Storage.StorageFile.GetFileFromApplicationUriAsync(newUri("ms-appdata:///local/CaptainsLog.store"));

```

//WP8 Storage APIs

Windows.Storage.StorageFolderlocalFolder=Windows.Storage.ApplicationData.Current.LocalFolder;

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

```

使用WP7.1独立存储API保存数据

Isolated Storage Classes

IsolatedStorageFile

IsolatedFileStream

IsolatedStorageSettings

Saving Data

Private void saveGameToIsolatedStorage(string message)

{

Using(isolatedStorageFileisf=IsolatedStorageFile.GetUserStoreForApplication())

{

Using(IsolatedStorageFileSytreamrawStream=isf.CreaqteFile("MyFile.store"))

{

StreamWriter writer=new StreamWriter(rawStream);

Writer.WriteLine(message);      //save the message

Writer.Close();

}

}

 

Loading Data

Private String loadString()

{

String result=null;

Using(IsolatedStorageFileisf=IsolostedStorageFile.GetUserStoreForApplication())

{

If(isf.FileExists("Myfile.store")

{

Using(IsolatedStorageFileStreamrawStream=isf.OpenFile(filename,System.IO.FileMode.Open())

{

StreamReader  reader=newStreamReader(rawStream);

Result=reader.ReadLine();

Reader.Close();

}

}

}

Return result;

}

在应用设备中保存数据

Void saveString(streing message,string name)

{

IsolatedStorageSettings.ApplicationSettings[name]=message;

IsolatedStorageSettings.ApplicationSettings.Save();

 

 

使用设置存储

使用StorageFolder保存数据

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, justopen it

StorageFile storageFile=await storageFile.OpenStreamForWreteAsync();

Using(StreamWriter writer=new StreamWriter(writeStream))

{

Await writer.WriteAsync(logData);

}

}

使用ms-appdata:///local/or ms-appx:///访问文件

//There's no FileExists method in WinRT, so have to try to open itand catch exception instead

StorageFile storageFile=null;

Bool fileExists=false;

Try

{

//Try to open file using URI

storageFile=await StorageFile.GetFileFromApplicationUriAsync(

NewUri("ms-appdata:///local/Myfile,store")；

fileExists=true;

}

Catch(FileNotFoundException)

{

fileExists=false;

}

If(!fileExists)

{

AwaitApplicationData.Current.LoaclFolder.CreateFileAsync("Myfile.store",CreationCollisionOption.FaqilIfExists);

}

```

 

Windows.comStorage（WindowsPhoneRunting）编程

Windows Phone8和Windows8兼容性

在Windows8中您可以以编程的方式加载应用程序包中的图像文件，将图像加载至XAML<Image>元素，代码如下：

RecipeImage.Source=new System.Windows.Media.Imaging.BitmapImage(newUri(@"ms-appx:///Images/french/French_1_600_C.jpg",UriKind.RelativeOrAbsolute));

在WindowsPhone8中不能使用这样的URI语法，只能使用WindowsPhone OS7.1中的相对路径，代码如下：

RecipeImage.Source=newSystem.Windows.Media.Imgine.BitmapImage("/Images/french/French_1_600_C.jpg");

 

特殊文件夹

Shared/Media专辑封面

Shared/ShellContent图块

Shared/Transfers后台文件传输

数据的序列化和反序列化(将对象集合的属性写入文件以便永久保存）

->Deactivated/Closig->Not running->Launching->Running

使用DataContractSerializer实现序列化

Public class MyDataSerializer<TheDataType>

{

Public static async Task SaveObjectsAsync(TheDataTypesourceData,String targetFileName)

{

StorageFile file=await|ApplicationData.Current.LocalFolder.CreateFileAsync(

targertFileName,CreationCollisionOpetion.ReplaceExisting);

Var outStream=await file.OpenStreamForWriteAsync();

DataContractSerializer serializer=newDataContractSerizlizer(typeof(TheDataType));

Serializer.WriteObject(outStream,sourceData);

Await outStream.FlushAsync();

outStream.Close();

}

```

}

使用DataContractSerializer实现反序列化

Puboic class MyDataSerializer<TheDataType>

{

Public static async Task<TheDataType>RestoreObjectsAsync(string fileName)

{

StorageFile file=awaitApplicationData.Current.LocalFolder.GetFileAsync(fileName);

Var inStream=await file.OpenstreamForReadAsync();

//Deserialize the objects.

DataContractSerializer serializer=newDataContractSerializer(typeof(TheDataType));

TheDataType data=(TheDataType)serializer.ReadObject(inStream);

inStream.Close();

Return data;

}

````

}

 

使用独立存储资源管理器ISETool.exe

语法：

Ts-Take snapshot

Re-Restore snapshot

Dir-lists the files or dirextories

 

使用可移动的SD卡

外部存储（SD）卡（Windows Phone8 支持使用SD卡）

<Extensions>

<FileTypeAssociation Name="foo"TaskID="_default" NavUriFragment="fileToken=%s">

<SupportedFileTypes>

<FileTypeContentType="application/foo">.foo</FileType>

</SupportedFileTypes>

</FileTypeAssociation>

</Extensions>

在WMAppMainifest.xml中声明文件关联

<Extensions>

<FileTypeAssociation Name="foo"TaskID="_default" NavUriFragment="fileToken=%s">

<SupportedFileTypes>

<FileTypeContentType="application/foo">.foo</FileType>

</SupportedFileTypes>

</FileTypeAssociation>

</Extensions>

最佳方法：

配额管理

Serialization and Threads