Programatically add file in folder in sharepoint Document Library

How to Programatically add file in folder in sharepoint Document Library

Programatically add file in folder in sharepoint Document Library 

                    SPSite site = SPContext.Current.Site;
                    SPWeb oweb = site.OpenWeb();
                    oweb.AllowUnsafeUpdates = true;
                    SPList olist = oweb.Lists[listid];
                    SPListItem oitem = olist.GetItemById(Convert.ToInt32(itemid));
                    SPList list = oweb.Lists["SharedDocuments"];
                    SPFolder folder = list.RootFolder.SubFolders["Folder1"];
                    byte[] file = oitem.File.OpenBinary();
                    string dsturl = list.RootFolder.SubFolders["Folder1"].Url + "/" + oitem.File.Name;
                    SPFile myfile = folder.Files.Add(dsturl, file, true);
                    list.Update();