Change Font Name and Size of whole document using .NET

I have a word file.so I want use aspose.word to change all of the text font size and font name.How I can do?I think DocumentBuilder cannoe be use in this situation.DocumentBuilder can set font when you generate text,but now,I have a word file,it has contaioned text!

@futureflsl,

You can build logic on the following code to change the Font name and Font size of entire Word document:

Document doc = new Document("C:\\temp\\input.docx");
FontChanger changer = new FontChanger();
doc.Accept(changer);
doc.Save("C:\\temp\\21.1.docx");

class FontChanger : DocumentVisitor
{
    ///
    /// Called when a FieldEnd node is encountered in the document.
    ///
    public override VisitorAction VisitFieldEnd(FieldEnd fieldEnd)
    {
        //Simply change font name
        ResetFont(fieldEnd.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a FieldSeparator node is encountered in the document.
    ///
    public override VisitorAction VisitFieldSeparator(FieldSeparator fieldSeparator)
    {
        ResetFont(fieldSeparator.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a FieldStart node is encountered in the document.
    ///
    public override VisitorAction VisitFieldStart(FieldStart fieldStart)
    {
        ResetFont(fieldStart.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a Footnote end is encountered in the document.
    ///
    public override VisitorAction VisitFootnoteEnd(Footnote footnote)
    {
        ResetFont(footnote.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a FormField node is encountered in the document.
    ///
    public override VisitorAction VisitFormField(FormField formField)
    {
        ResetFont(formField.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a Paragraph end is encountered in the document.
    ///
    public override VisitorAction VisitParagraphEnd(Paragraph paragraph)
    {
        ResetFont(paragraph.ParagraphBreakFont);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a Run node is encountered in the document.
    ///
    public override VisitorAction VisitRun(Run run)
    {
        ResetFont(run.Font);
        return VisitorAction.Continue;
    }

    ///
    /// Called when a SpecialChar is encountered in the document.
    ///
    public override VisitorAction VisitSpecialChar(SpecialChar specialChar)
    {
        ResetFont(specialChar.Font);
        return VisitorAction.Continue;
    }

    private void ResetFont(Aspose.Words.Font font)
    {
        font.Name = mNewFontName;
        font.Size = mNewFontSize;
    }

    private string mNewFontName = "Times New Roman";
    private double mNewFontSize = 8;
}