wb = xlsx_package.workbook
wb.styles do |s|
  sz_all = s.add_style :border => { :style => :thin, :color =>"000000" },:alignment => {:horizontal => :center}
  blue_cell = s.add_style :bg_color => "FAEBDC", :sz => 10,:height => 20,:b => true, :border => { :style => :thin, :color =>"000000" },:alignment => {:horizontal => :center}

  wb.add_worksheet(:name =>"学生成绩") do |sheet|
    sheet.add_row table_columns,:height =>20, :style => blue_cell
    sheet.column_info.first.width = 12
    task_users.each do |user|
      sheet.add_row user, :height =>20, :style => sz_all
    end  #each_widh_index
    sheet.column_widths *([25]*sheet.column_info.count)
    sheet.column_info.first.width = 12
  end  #add_worksheet
end