C# word操作

Application word = new Application();
            Document doc = null;
            if (word == null)
            {
                return;
            }
            word.Visible = false;
            word.DisplayAlerts = WdAlertLevel.wdAlertsNone;
            object path = Server.MapPath("..") + "\\Report\\xkcysqb.rtf";

            object oMissing = System.Reflection.Missing.Value;
            doc = word.Documents.Add(ref path, oMissing, oMissing, oMissing);//加载模板
            doc.Select();
            object findText = "$$sqr$$";
            object replaceText = dt.Rows[0]["sqr"].Equals(DBNull.Value) ? "" : dt.Rows[0]["sqr"].ToString();
            object replace = WdReplace.wdReplaceAll;
            doc.Content.Find.Execute(ref findText, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, replaceText, replace, oMissing, oMissing, oMissing, oMissing);//标签式替换内容

            findText = "$$date$$";
            replaceText = dt.Rows[0]["sqdate"].Equals(DBNull.Value) ? "" : dt.Rows[0]["sqdate"].ToString();
            doc.Content.Find.Execute(ref findText, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, oMissing, replaceText, oMissing, oMissing, oMissing, oMissing, oMissing);
                       

            String filename = Server.MapPath("..") + "\\Excel\\xkcysqb.rtf";
            if (File.Exists(filename))
            {
                File.Delete(filename);
            }
            doc.SaveAs(filename, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
            word.Quit(oMissing,oMissing,oMissing);
            if (doc != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(doc);
                doc = null;
            }
            if (word != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(word);
                word = null;
            }

            System.GC.Collect();