从Windows Phone 8的隔离存储中解析XML文件

Question

For the sake of experimentation, I'm trying to create a new XML file and save it to isolated storage, display it in the app as message box, open and save it with no changes made, then display it again.

This is the XML I'm trying to make:

<?xml version="1.0" encoding="utf-8"?>
<houses />

This is my code:

public void InsertNewRoom()
{
    XDocument doc = null;
    CreateNewFile(doc); //create the file in isolated storage.
    ReadIsoStream(doc); //Display file as a new messagebox.
    OpenAndCloseFile(doc); //Open and save the file, no changes made.
    ReadIsoStream(doc); //Display file again.
}

public void OpenAndCloseFile(XDocument doc)
{
    using (IsolatedStorageFile isoStory = IsolatedStorageFile.GetUserStoreForApplication())
    {
        using (IsolatedStorageFileStream isoStream = new IsolatedStorageFileStream("WizardResults.xml", FileMode.Open, isoStory))
        {

            doc = XDocument.Load(isoStream);
            doc.Save(isoStream);
        }
    }
    ReadIsoStream(doc);
}

public void CreateNewFile(XDocument doc)
{
    using (IsolatedStorageFile isoStore = IsolatedStorageFile.GetUserStoreForApplication())
    {
        //if (!isoStore.FileExists("WizardResults.xml"))
        {
            using (IsolatedStorageFileStream isoStream = new IsolatedStorageFileStream("WizardResults.xml", FileMode.Create, isoStore))
            {
                XDeclaration dec = new XDeclaration("1.0", "utf-8", "yes");
                doc = new XDocument(dec, new XElement("houses"));
                doc.Save(isoStream, SaveOptions.None);
            }
        }
    }
}
public void ReadIsoStream(XDocument doc)
{
    using (IsolatedStorageFile isoStory = IsolatedStorageFile.GetUserStoreForApplication())
    {
        using (IsolatedStorageFileStream isoStream = new IsolatedStorageFileStream("WizardResults.xml", FileMode.Open, isoStory))
        {
            using (XmlReader reader = XmlReader.Create(isoStream))
            {
                XDocument xml = XDocument.Load(reader);

                MessageBox.Show(xml.ToString());
            }
        }
    }
}

The first ReadIsoStream() runs perfectly well. Once the second ReadIsoStream() attempts to run, I get this error message:

Additional information: Unexpected XML declaration. The XML declaration must be the first node in the document, and no white space characters are allowed to appear before it. Line 2, position 13.

Help me, please?

Answer 1

It is saying that the first node of your document must have XML declarationg. This one ->

<?xml version="1.0" encoding="utf-8"?>