用流写入EXCEL文件方式怎么控制 单元格写入的宽度呢?   
 this.saveFileDialog1.Filter = "EXCEL文件(*.xls)|*.xls|所有文件(*.*)|*.*";                    this.saveFileDialog1.Title = "保存导出数......";                                         this.saveFileDialog1.InitialDirectory = @"c:\";                             
 this.saveFileDialog1.RestoreDirectory = true;                                                this.saveFileDialog1.ShowHelp = true;                                                        if (this.saveFileDialog1.ShowDialog() == DialogResult.OK)
                    {                        string fileName = saveFileDialog1.FileName;   //文件名   
                        string file = strOutput;         //需要保存的文件内容   
                        StreamWriter sw = new StreamWriter(fileName, false, Encoding.Default);  //先using System.IO;   
                        sw.Write(file);
                        sw.Close();
                    }