如何在C# VSTO Word插件中设置页眉和页脚文本以及页码？

private void ThisAddIn_Startup(object sender, System.EventArgs e)
{
    this.Application.DocumentOpen += new Word.ApplicationEvents4_DocumentOpenEventHandler(Application_DocumentOpen);
}

private void Application_DocumentOpen(Word.Document doc)
{
    Word.Section section = doc.Sections.First;
    Word.HeaderFooter header = section.Headers[Word.WdHeaderFooterIndex.wdHeaderFooterPrimary];
    Word.HeaderFooter footer = section.Footers[Word.WdHeaderFooterIndex.wdHeaderFooterPrimary];

    // 设置页眉文本
    header.Range.Text = "这是页眉文本";

    // 设置页脚文本
    footer.Range.Text = "这是页脚文本";

    // 设置页码
    footer.PageNumbers.Add(Word.WdPageNumberAlignment.wdAlignPageNumberCenter);
}

private void ThisAddIn_Startup(object sender, System.EventArgs e)
{
    this.Application.DocumentOpen += new Word.ApplicationEvents4_DocumentOpenEventHandler(Application_DocumentOpen);
    this.Application.DocumentNew += new Word.ApplicationEvents4_DocumentNewEventHandler(Application_DocumentNew);
}

private void Application_DocumentNew(Word.Document doc)
{
    Word.Section section = doc.Sections.First;
    Word.HeaderFooter header = section.Headers[Word.WdHeaderFooterIndex.wdHeaderFooterPrimary];
    Word.HeaderFooter footer = section.Footers[Word.WdHeaderFooterIndex.wdHeaderFooterPrimary];

    // 设置页眉文本
    header.Range.Text = "这是页眉文本";

    // 设置页脚文本
    footer.Range.Text = "这是页脚文本";

    // 设置页码
    footer.PageNumbers.Add(Word.WdPageNumberAlignment.wdAlignPageNumberCenter);
}