Data Structures on the Windows Phone 7: Reading & Writing Isolated Storage

How do you put data into isolated storage, how do you read data that is in isolated storage? 

You’re right, I have been a big tease around the phone and lists and reading/writing to isolated storage. 

In a later example, I will cover the use off lists into and out of isolated storage. 

IsolatedStorageFile

To save or retrieve files you use the IsolatedStorageFile class.  As we have seen in the previous blog,

• Data Structures: Creating Isolated Storage Files and Directories

I used the Windows 7 approach,  In this blog I show  the code for the Phone 7.  It has been checked that it works in the emulator, to make this work, you add code to the Initialize Method and the Draw Method.  This uses the default Windows Phone Emulator Code, it works as written, to enlarge the font, make the changes to the spritefont1.sprintfont file you added so that you added to draw the fonts for the message.  This is a very simple app,

After opening the Windows Phone XNA Application, add a SprintFont file to the Content, like the following:

First: Add the references to your program so that you can perform the isolated storage.

To the using section at the top of the class add:

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

 using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Input.Touch;
using Microsoft.Xna.Framework.Media;
using System.IO;
using System.IO.IsolatedStorage;

Second: At the top of the class add the Spritefont variable and the Vector2 variable to display the Fonts:

     public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        SpriteFont Font1;
        Vector2 FontPos;

Third: To the Initialize method, add the following code:

        protected override void Initialize()
        {
            spriteBatch = new SpriteBatch(GraphicsDevice);
            Font1 = Content.Load<SpriteFont>("SpriteFont1");                        
            FontPos = new Vector2(graphics.GraphicsDevice.Viewport.Width / 2,
                graphics.GraphicsDevice.Viewport.Height / 2);
            /***************************************************************************
             ********************* ISOLATED STORAGE RELATED CODE ***********************/
            /*****************Obtain the virtual store for application*****************/
            IsolatedStorageFile myStore = IsolatedStorageFile.GetUserStoreForApplication();
            
            /*****************Create a new folder and call it "ImageFolder"************/
            myStore.CreateDirectory("ImageFolder");

            /**********   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("ImageFolder\\myFile.txt", 
                                    FileMode.OpenOrCreate, myStore));
            
            writeFile.WriteLine("Happy New Year");
            writeFile.Close();
            /******************** END OF THE ISOLATED STORAGE RELATED CODE **************
             *****************************************************************************/

            base.Initialize();
        }

Now, the Draw Method, make these changes:

        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);
            /*****************************************************************
             *******    Start of reading data out of IsolatedStorageFile    **
             *******    Obtain a virtual store for application              */
            IsolatedStorageFile myStore = 
                    IsolatedStorageFile.GetUserStoreForApplication();
            //The following code will open and read the contents of myFile.txt
            StreamReader readFile = null;
                readFile = new StreamReader(new 
                                            IsolatedStorageFileStream(
                                            "ImageFolder\\myFile.txt", 
                                             FileMode.Open, myStore
                                             )
                                             );
                string fileText = readFile.ReadLine();                                
                readFile.Close();
            /********   End of code to reading data out of IsolatedStorageFile **
             ********************************************************************/

            /**************************************************************
              ****************** Code added to print out to the  ************
              ******************* phone screen "Happy New Year"  ************
              ***************************************************************/
             spriteBatch.Begin();             
                Vector2 FontOrigin = Font1.MeasureString(fileText) / 2;
                // Draw/Write/Print the string
                spriteBatch.DrawString(Font1, fileText, FontPos, Color.OrangeRed,
                                0, FontOrigin, 1.0f, SpriteEffects.None, 0.5f);
                spriteBatch.End();
                /*****************  End of the Code to print out to the ******
                 *****************   phone screen "Happy New Year" ************/

            base.Draw(gameTime);
        }

Finally run your code and you have successfully wrote and read from isolated storage!

Now a few words for the crawlers, this is a test of what happens when I put the Technorati Tags/words on a page with a short phrase associated with them.  The first word in each cell is the tag followed by a short phrase.  I will then pull it off the page on Monday and examine the traffic flow.  I will share this information with you the reader. 

NNNN

IsoStoreDemo.zip