IGeekShop案例7-用户名异步校验

怼烎@ 2024-04-17 14:09 67阅读 0赞

# IGeekShop案例7-用户名异步校验 #

## 1 register.jsp代码 ##

## 2 web层 ##

public class CheckUsernameServlet extends HttpServlet {
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            
            //获得要校验的用户名
            String username = request.getParameter("username");
            
            //传递username到service
            UserService service = new UserService();
            boolean isExist = false;
            try {
                isExist = service.checkUsername(username);
            } catch (SQLException e) {
                e.printStackTrace();
            }
            //isExist是Boolean形的，所以不用加引号。
            //如果写回去的是一个String类型格式如下
            //"{\"namet\":\""+name+"\"}"
            response.getWriter().write("{\"isExist\":"+isExist+"}");
            
        }
    
        protected void doPost(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            doGet(request, response);
        }
    }

## 3 service层 ##

public boolean checkUsername(String username) throws SQLException {
            
            UserDao dao = new UserDao();
            Long isExist = dao.checkUsername(username);
            
            return isExist>0?true:false;
        }

## 4 dao层 ##

public class UserDao {
    
        public Long checkUsername(String username) throws SQLException {
            QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
            String sql = "select count(*) from user where username=?";
            Long query = (Long) runner.query(sql, new ScalarHandler(), username);
            return query;
        }
    
    }