使用Excel打印功能时为WPF DataGrid表头添加下划线

问题分析 #

你当前代码里的下划线设置是给所有单元格统一添加，且放在数据行循环里重复执行，没有单独针对表头行（第1行）做样式设置，同时还误用了属性——应该用Font.Underline而非Font.FontStyle来设置下划线，这就是表头下划线不生效的核心原因。

修改方案 #

下面是调整后的完整代码，重点优化了表头样式设置逻辑，并补充了Excel资源释放逻辑避免进程残留：

private void OnDataGridPrinting(object sender, RoutedEventArgs e)
{
    System.Windows.Controls.PrintDialog Printdlg = new System.Windows.Controls.PrintDialog();
    if ((bool)Printdlg.ShowDialog().GetValueOrDefault())
    {
        // 创建Excel应用实例
        Microsoft.Office.Interop.Excel._Application app = new Microsoft.Office.Interop.Excel.Application();
        // 创建新工作簿
        Microsoft.Office.Interop.Excel._Workbook workbook = app.Workbooks.Add(Type.Missing);
        Microsoft.Office.Interop.Excel._Worksheet worksheet = null;
        app.Visible = false;
        
        // 获取并激活第一个工作表
        worksheet = workbook.Sheets["Sheet1"];
        worksheet = workbook.ActiveSheet;
        worksheet.Name = SelectedCustomer.CustName;

        CollectionViewSource itemCollectionViewSources;
        itemCollectionViewSources = (CollectionViewSource)(FindResource("ItemCollectionViewSources"));

        // 写入DataGrid表头到Excel第1行
        for (int i = 1; i < dgEndOfYear.Columns.Count + 1; i++)
        {
            worksheet.Cells[1, i] = dgEndOfYear.Columns[i - 1].Header;
        }

        // 单独设置表头样式：下划线+居中对齐
        var headerRange = worksheet.Range[worksheet.Cells[1, 1], worksheet.Cells[1, dgEndOfYear.Columns.Count]];
        headerRange.Font.Underline = Microsoft.Office.Interop.Excel.XlUnderlineStyle.xlUnderlineStyleSingle;
        headerRange.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;

        // 设置全局列宽和数据单元格对齐方式（移到循环外，仅执行一次）
        worksheet.Columns.ColumnWidth = 14;
        worksheet.Cells.Style.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignCenter;

        // 写入DataGrid数据行到Excel
        for (int i = 0; i < CustomerEOYTotals.Count; i++)
        {
            absvwEndOfYearTotal1 line = CustomerEOYTotals[i];
            worksheet.PageSetup.CenterHeader = "&UEnd Of Year Report " + CurrentYear;
            worksheet.Cells[i + 2, 1] = line.CalendarYear;
            worksheet.Cells[i + 2, 2] = line.CustName;
            worksheet.Cells[i + 2, 3] = line.MonthName;
            worksheet.Cells[i + 2, 4] = line.SumGal.Value.ToString();
            worksheet.Cells[i + 2, 5] = line.Manifest;
        }

        // 打印工作簿
        workbook.PrintOut();

        // 释放Excel资源，避免后台进程残留
        workbook.Close(false);
        app.Quit();
        System.Runtime.InteropServices.Marshal.ReleaseComObject(worksheet);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(app);
    }
}

关键改动说明 #

1. 用Range选中整个表头行，单独对其设置下划线样式，纠正了之前的属性误用
2. 将列宽、全局对齐等重复操作移到数据循环外，提升代码执行效率
3. 添加Excel资源释放逻辑，防止打印完成后后台残留Excel进程

内容的提问来源于stack exchange，提问作者Mr.E