import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.*; import java.util.*; import java.sql.*; import javax.naming.*; import javax.sql.*; public final class LoginAction extends Action {    public ActionForward execute(       ActionMapping mapping,       ActionForm form,       HttpServletRequest request,       HttpServletResponse response)       throws Exception {       // 画面よりログインIDとパスワードを取得する       LoginForm loginForm = (LoginForm)form;       String id = loginForm.getId();       String password = loginForm.getPassword();       // 初期値を設定する       InitialContext ic = null;       DataSource ds = null;       Connection con = null;       PreparedStatement ps = null;       ResultSet rs = null;       int count = 0;       String status = null;       List usersList = null;       ActionMessages errors = new ActionMessages();          try {          // DBより登録者の情報を取得する          ic = new InitialContext();          ds = (DataSource)ic.lookup("java:comp/env/jdbc/mysql");          con = ds.getConnection();          ps = con.prepareStatement(             "select id, password from users where id = ?");          ps.setString(1, id);          rs = ps.executeQuery();          // 認証を行う          while (rs.next()) {             count++;             if (count == 1) {                // ログインIDとパスワードが登録者の情報と                // 一致しなければ認証失敗                if (! id.equals(rs.getString("id")) ||                   ! password.equals(rs.getString("password"))) {                   errors.add(                      ActionMessages.GLOBAL_MESSAGE,                      new ActionMessage("errors.login"));                }             // ログインIDが2件以上存在したら認証失敗             } else {                errors.add(                   ActionMessages.GLOBAL_MESSAGE,                   new ActionMessage("errors.login"));             }          }          // ログインIDが0件なら認証失敗          if (count == 0) {             errors.add(                ActionMessages.GLOBAL_MESSAGE,                new ActionMessage("errors.login"));          }          // 認証に成功した場合、トップ画面に          // 登録者の一覧を表示する          if (errors.isEmpty()) {             status = "success";             usersList = new ArrayList();             ps = con.prepareStatement(                "select id, name from users order by id");             rs = ps.executeQuery();             while (rs.next()) {                SampleUser sampleUser = new SampleUser();                sampleUser.setId(rs.getString("id"));                sampleUser.setName(rs.getString("name"));                usersList.add(sampleUser);             }             request.setAttribute("userslist", usersList);          // 認証に失敗した場合、ログイン画面に          // エラーメッセージを表示する          } else {             status = "error";             saveErrors(request, errors);          }       } catch (Exception e) {          throw e;       } finally {          con.close();       }       return (mapping.findForward(status));    } }