C# winfrom 导出word

   　　　　　　public void ExportWord(string str){

　　　 　　　　System.Windows.Forms.SaveFileDialog objSave = new System.Windows.Forms.SaveFileDialog();
                objSave.Filter = "(*.doc)|*.doc|" + "(*.*)|*.*";//+ "(*.txt)|*.txt|"

                objSave.FileName = DateTime.Now.ToString("yyyyMMddHHmm") + ".doc";

                if (objSave.ShowDialog() == DialogResult.OK)
                {

                    Microsoft.Office.Interop.Word.ApplicationClass MyWord = new Microsoft.Office.Interop.Word.ApplicationClass();
                    Microsoft.Office.Interop.Word.Document MyDoc;

                    Object Nothing = System.Reflection.Missing.Value;

                    MyDoc = MyWord.Documents.Add(ref Nothing, ref Nothing, ref Nothing, ref Nothing);

                    MyDoc.Paragraphs.Last.Range.Font.Name = "宋体";

                    MyDoc.Paragraphs.Last.Range.Text = this.richTextBox1.Text;

                    object MyFileName = objSave.FileName;
                    //将WordDoc文档对象的内容保存为DOC文档 
                    MyDoc.SaveAs(ref MyFileName, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing, ref Nothing);
                    //关闭WordDoc文档对象 
                    MyDoc.Close(ref Nothing, ref Nothing, ref Nothing);
                    //关闭WordApp组件对象 
                    MyWord.Quit(ref Nothing, ref Nothing, ref Nothing);
                    MessageBox.Show("文件保存成功", "信息提示", MessageBoxButtons.OK, MessageBoxIcon.Information);

                    //this.txtDetail.SaveFile(objSave.FileName,RichTextBoxStreamType.PlainText);
                }}