将 List<Obj> 集合， 导出至 Excel

主代码在这：http://www.codeproject.com/Articles/120480/Export-to-Excel-Functionality-in-WPF-DataGrid

黑人老外写的代码，条理很清晰。

↓ 用法：（由于我直接就是用List泛型集合，就不新定义一个集合对象了，所以封装了下：）

private void Export2Excel<T>(IEnumerable<T> pValues) where T : class
{
    var saveE = new ExportToExcel<T, List<T>>();
    saveE.DataToPrint = pValues.ToList();
    saveE.GenerateReport();
}

↓ 稍微封装下，用起来就更简单了，一句就完了

//比如，我有个音乐集合
//List<MyMusic> sources

Export2Excel(sources);

看起来真的好爽，一句就完了，贴一下老外的代码吧。

    //ExportToExcel<Book, Books> s = new ExportToExcel<Book, Books>();
    //ICollectionView view = CollectionViewSource.GetDefaultView(dgBook.ItemsSource);
    //s.DataToPrint = (Books)view.SourceCollection;
    //s.GenerateReport();

    /// <summary>
    /// 导出 Excel 类，（带示例）
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <typeparam name="U"></typeparam>
    public class ExportToExcel<T, U>
        where T : class
        where U : List<T>
    {
        public List<T> DataToPrint;

        // Excel 对象实例.
        private Excel.Application _excelApp = null;
        private Excel.Workbooks _books = null;
        private Excel._Workbook _book = null;
        private Excel.Sheets _sheets = null;
        private Excel._Worksheet _sheet = null;
        private Excel.Range _range = null;
        private Excel.Font _font = null;
        // 可选 参数
        private object _optionalValue = Missing.Value;

        /// <summary>
        /// 生成报表，和其他功能
        /// </summary>
        public void GenerateReport()
        {
            try
            {
                if (DataToPrint != null)
                {
                    if (DataToPrint.Count != 0)
                    {
                        Mouse.SetCursor(Cursors.Wait);
                        CreateExcelRef();
                        FillSheet();
                        OpenReport();
                        Mouse.SetCursor(Cursors.Arrow);
                    }
                }
            }
            catch (Exception e)
            {
                MessageBox.Show("Excel导出失败！
", e.Message);
            }
            finally
            {
                ReleaseObject(_sheet);
                ReleaseObject(_sheets);
                ReleaseObject(_book);
                ReleaseObject(_books);
                ReleaseObject(_excelApp);
            }
        }
        /// <summary>
        /// 展示 Excel 程序
        /// </summary>
        private void OpenReport()
        {
            _excelApp.Visible = true;
        }
        /// <summary>
        /// 填充 Excel sheet
        /// </summary>
        private void FillSheet()
        {
            object[] header = CreateHeader();
            WriteData(header);
        }
        /// <summary>
        /// 将数据写入 Excel sheet
        /// </summary>
        /// <param name="header"></param>
        private void WriteData(object[] header)
        {
            object[,] objData = new object[DataToPrint.Count, header.Length];

            for (int j = 0; j < DataToPrint.Count; j++)
            {
                var item = DataToPrint[j];
                for (int i = 0; i < header.Length; i++)
                {
                    var y = typeof(T).InvokeMember(header[i].ToString(),
                    BindingFlags.GetProperty, null, item, null);
                    objData[j, i] = (y == null) ? "" : y.ToString();
                }
            }
            AddExcelRows("A2", DataToPrint.Count, header.Length, objData);
            AutoFitColumns("A1", DataToPrint.Count + 1, header.Length);
        }
        /// <summary>
        /// 根据数据拟合 列
        /// </summary>
        /// <param name="startRange"></param>
        /// <param name="rowCount"></param>
        /// <param name="colCount"></param>
        private void AutoFitColumns(string startRange, int rowCount, int colCount)
        {
            _range = _sheet.get_Range(startRange, _optionalValue);
            _range = _range.get_Resize(rowCount, colCount);
            _range.Columns.AutoFit();
        }
        /// <summary>
        /// 根据属性名创建列标题
        /// </summary>
        /// <returns></returns>
        private object[] CreateHeader()
        {
            PropertyInfo[] headerInfo = typeof(T).GetProperties();

            // 为 标头 创建 Array
            // 开始从 A1 处添加
            List<object> objHeaders = new List<object>();
            for (int n = 0; n < headerInfo.Length; n++)
            {
                objHeaders.Add(headerInfo[n].Name);
            }

            var headerToAdd = objHeaders.ToArray();
            AddExcelRows("A1", 1, headerToAdd.Length, headerToAdd);
            SetHeaderStyle();

            return headerToAdd;
        }
        /// <summary>
        /// 列标题设置为加粗字体
        /// </summary>
        private void SetHeaderStyle()
        {
            _font = _range.Font;
            _font.Bold = true;
        }
        /// <summary>
        /// 添加行
        /// </summary>
        /// <param name="startRange"></param>
        /// <param name="rowCount"></param>
        /// <param name="colCount"></param>
        /// <param name="values"></param>
        private void AddExcelRows(string startRange, int rowCount,
        int colCount, object values)
        {
            _range = _sheet.get_Range(startRange, _optionalValue);
            _range = _range.get_Resize(rowCount, colCount);
            _range.set_Value(_optionalValue, values);
        }
        /// <summary>
        /// 创建 Excel 传递的参数实例
        /// </summary>
        private void CreateExcelRef()
        {
            _excelApp = new Excel.Application();
            _books = (Excel.Workbooks)_excelApp.Workbooks;
            _book = (Excel._Workbook)(_books.Add(_optionalValue));
            _sheets = (Excel.Sheets)_book.Worksheets;
            _sheet = (Excel._Worksheet)(_sheets.get_Item(1));
        }
        /// <summary>
        /// 释放未使用的 COM 对象
        /// </summary>
        /// <param name="obj"></param>
        private void ReleaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
                obj = null;
            }
            catch (Exception ex)
            {
                obj = null;
                MessageBox.Show(ex.Message.ToString());
            }
            finally
            {
                GC.Collect();
            }
        }
    }