All about WP7 Isolated Storage - Read and Save Text files

published on: 3/21/2011 | Views: N/A | Tags: IsoStore

by WindowsPhoneGeek

This is the fourth article from the “All about WP7 Isolated Storage ” series of short articles focused on real practical examples with source code rather than a plain theory. I am going to talk about how to read and save Text file into Isolated Storage.

• All about WP7 Isolated Storage – intro to Isolated Storage
• All about WP7 Isolated Storage - Folders and Files
• All about WP7 Isolated Storage - Store data in IsolatedStorageSettings
• All about WP7 Isolated Storage - Read and Save Text files
• All about WP7 Isolated Storage - Read and Save XML files using XmlSerializer
• All about WP7 Isolated Storage - Read and Save XML files using XmlWriter
• All about WP7 Isolated Storage - Read and Save Images
• All about WP7 Isolated Storage - Read and Save Captured Image
• All about WP7 Isolated Storage - Read and Save Binary files
• All about WP7 Isolated Storage - File manipulations
• All about WP7 Isolated Storage - Recommendations and Best Practices
• All about WP7 Isolated Storage - open source Databases and Helper libraries

To begin with lets first create a sample Windows Phone 7 application project. Next include the following namespaces in MainPage.xaml.cs (alternatively you can use the code in another page):

using System.IO;
using System.IO.IsolatedStorage;

Reading and saving files to the Isolated Storage is a common task for many WP7 applications.

Basically we use IsolatedStorageFileStream class  to to read, write and create files in isolated storage. Since this class extends FileStream, you can use an instance of IsolatedStorageFileStream in most situations where a FileStream might otherwise be used, such as to construct a StreamReader or StreamWriter.

Save New Text File to Isolated Storage

In this example at first we create a new myFile.txt text file in the Isolated Storage and after that write some string content into it.

IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();

//create new file
using (StreamWriter writeFile = new StreamWriter(new IsolatedStorageFileStream("myFile.txt", FileMode.Create, FileAccess.Write, myIsolatedStorage)))
{
    string someTextData = "This is some text data to be saved in a new text file in the IsolatedStorage!";
    writeFile.WriteLine(someTextData);
    writeFile.Close();
}

NOTE: When creating new file we use  FileMode.Create, when we want to write to a file we use FileAccess.Write! You can find a list of all FileAccess possibilities here.

Write to existing Text File in Isolated Storage

In this example at first open an existing myFile.txt text file from the Isolated Storage and after that write some additional string content into it.

IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();

//Open existing file
IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("myFile.txt", FileMode.Open, FileAccess.Write);
using (StreamWriter writer = new StreamWriter(fileStream))
{
    string someTextData = "Some More TEXT Added:  !";
    writer.Write(someTextData);
    writer.Close();
}

NOTE: When open an existing file from the Isolated Storage we use  FileMode.Open, when we want to write to a file we use FileAccess.Write! You can find a list of all FileAccess possibilities here.

Read Text File from Isolated Storage

In this example at first open an existing myFile.txt text file from the Isolated Storage and read its content. After that the content is visualized in a TextBlock.

IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("myFile.txt", FileMode.Open, FileAccess.Read);
using (StreamReader reader = new StreamReader(fileStream))
{    //Visualize the text data in a TextBlock text
    this.text.Text = reader.ReadLine();
}

NOTE: When open an existing file from the Isolated Storage we use  FileMode.Open, when we want to read to a file we use FileAccess.Read! You can find a list of all FileAccess possibilities here.

Reading/Writing Text File in a Directory of the Isolated Storage

• Writing

//Obtain the virtual store for application
IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();

//Create a new folder and call it "ImageFolder"
myIsolatedStorage.CreateDirectory("TextFilesFolder");

//Create a new file and assign a StreamWriter to the store and this new file (myFile.txt)
//Also take the text contents from the txtWrite control and write it to myFile.txt
StreamWriter writeFile = new StreamWriter(new IsolatedStorageFileStream("TextFilesFolder\\myNewFile.txt", FileMode.OpenOrCreate, myIsolatedStorage));
string someTextData = "This is some text data to be saved in a new text file in the IsolatedStorage!";
writeFile.WriteLine(someTextData);
writeFile.Close();

• Reading

IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication();
IsolatedStorageFileStream fileStream = myIsolatedStorage.OpenFile("TextFilesFolder\\myNewFile.txt", FileMode.Open, FileAccess.Read);
using (StreamReader reader = new StreamReader(fileStream))
{
    this.text1.Text = reader.ReadLine();
}

NOTE: Take a look at All about WP7 Isolated Storage - Files and Folders for more info about directories.

Best Practices

1.) When working with files always use Using statement because it provides a convenient syntax that ensures the correct use of IDisposable objects.

2.) Always check if a Directory in which you want to create/read a File exists.

3.) Check for existing file before trying to read it

In this article I talked about reading and saving Text file into Isolated Storage. Here is the full source code.

Stay tuned with the rest of the posts. I hope that the article was helpful.

You can also follow us on Twitter @winphonegeek

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