DataTable保存为Excel或者Txt

保存为txt的时候，可保持原来的行列对齐，如下：

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.IO;
using System.Windows.Forms;
using System.Reflection;

namespace celiang
{
    public class saveDataTableToExcelTxt
    {
        public saveDataTableToExcelTxt(DataTable table,string fullName) 
        {
            string extention = Path.GetExtension(fullName);
            if(extention==".txt")//如果保存为txt文件
            {
                if(ExportToTxt(table,fullName)==true)
                {
                    MessageBox.Show("保存成功","提示");
                }
            }
            else if(extention==".xls")
            {
                if (ExportToExcel(table, fullName))
                {
                    MessageBox.Show("保存成功","提示");
                }
            }

        }
        /// <保存DataTable 到Excel>
        /// 
        /// </summary>
        /// <param name="table"></param>
        /// <param name="excelName"></param>
        /// <returns></returns>
        private bool ExportToExcel(System.Data.DataTable table, string excelName)
        {
            Microsoft.Office.Interop.Excel.Application oXL;
            Microsoft.Office.Interop.Excel.Workbook oWB;
            Microsoft.Office.Interop.Excel.Worksheet oSheet;
            Microsoft.Office.Interop.Excel.Range oRange;

            // Start Excel and get Application object. 
            oXL = new Microsoft.Office.Interop.Excel.Application();

            // Set some properties 
            oXL.Visible = false;
            oXL.DisplayAlerts = false;

            // Get a new workbook. 
            oWB = oXL.Workbooks.Add(Missing.Value);

            // Get the active sheet 
            oSheet = (Microsoft.Office.Interop.Excel.Worksheet)oWB.ActiveSheet;
            oSheet.Name = "Customers";

            // Process the DataTable 
            // BE SURE TO CHANGE THIS LINE TO USE *YOUR* DATATABLE 
            System.Data.DataTable dt = table;

            int rowCount = 1;
            foreach (DataRow dr in dt.Rows)
            {
                rowCount += 1;
                for (int i = 1; i < dt.Columns.Count + 1; i++)
                {
                    // Add the header the first time through 
                    if (rowCount == 2)
                    {
                        oSheet.Cells[1, i] = dt.Columns[i - 1].ColumnName;
                    }
                    oSheet.Cells[rowCount, i] = dr[i - 1].ToString();
                }
            }

            // Resize the columns 
            oRange = oSheet.get_Range(oSheet.Cells[1, 1],
                          oSheet.Cells[rowCount, dt.Columns.Count]);
            oRange.EntireColumn.AutoFit();

            // Save the sheet and close 
            oSheet = null;
            oRange = null;
            oWB.SaveAs(excelName, Microsoft.Office.Interop.Excel.XlFileFormat.xlWorkbookNormal,
                Missing.Value, Missing.Value, Missing.Value, Missing.Value,
                Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlExclusive,
                Missing.Value, Missing.Value, Missing.Value,
                Missing.Value, Missing.Value);
            oWB.Close(Missing.Value, Missing.Value, Missing.Value);
            oWB = null;
            oXL.Quit();

            // Clean up 
            // NOTE: When in release mode, this does the trick 
            GC.WaitForPendingFinalizers();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            GC.Collect();

            return true;
        }

        private bool ExportToTxt(System.Data.DataTable table ,string fullName)
        {
            int[] iColumnLength = new int[table.Columns.Count];
            FileStream fileStream = new FileStream(fullName, FileMode.Create);
            StreamWriter streamWriter = new StreamWriter(fileStream, System.Text.Encoding.Unicode);
            StringBuilder strBuilder = new StringBuilder();

            for (int i = 0; i < table.Columns.Count; i++)
            {
                int iLength = 0;
                for (int j = 0; j < table.Rows.Count; j++)
                {
                    if (iLength < (table.Rows[j][i].ToString()).Length)
                    {
                        iLength = (table.Rows[j][i].ToString()).Length;
                    }
                }
                iColumnLength[i] = iLength;
            }

            for (int i = 0; i < table.Rows.Count - 1; i++)
            {

                for (int j = 0; j < table.Columns.Count; j++)
                {
                    string str1 = table.Rows[i][j].ToString();
                    int iLength = str1.Length;
                    int iColumnWidth = iColumnLength[j] + 4;
                    for (int k = iLength; k < iColumnWidth; k++)
                    {
                        str1 += " ";
                    }
                    if (j == table.Columns.Count - 1)
                    {
                        strBuilder.AppendLine(str1);
                    }
                    else
                    {
                        strBuilder.Append(str1);
                    }
                }
            }

            streamWriter.WriteLine(strBuilder.ToString());
            streamWriter.Close();
            fileStream.Close();
            return true;
        }
    }
}