smbms超市管理系统之登录（查询）

在搭好数据库以及基础项目以后，现在开始进入登录功能的实现
以下是自己根据实体类将数据库表生成：
https://blog.csdn.net/weixin_44760375/article/details/120214314?spm=1001.2014.3001.5501
在涉及sql访问数据库时，一个bug折磨了我一整天

最后发现是 重复传入sql导致！！executeQuery（）方法不需要再传入sql

UserDaoImpl：

public class UserDaoImpl implements UserDao{

    public User getUser(Connection connecton, String userCode,String userPassword) {
        PreparedStatement s=null;
        ResultSet re=null;
        User user=null;
        String sql="select * from smbms_user where user_code=? and user_password=?";
        Object[] params={userCode,userPassword};
      ResultSet rs = BaseDao.execute(connecton, sql, params, re, s);
        try {
            if(rs.next()){
                user=new User();
                user.setUserCode(rs.getString("user_code"));
                user.setId((long) rs.getLong("id"));
                user.setAddress(rs.getString("address"));
                user.setBirthday(rs.getDate("birthday"));
                user.setGender(rs.getInt("gender"));
                user.setUserName(rs.getString("user_name"));
                user.setUserPassword(rs.getString("user_password"));
            }
            BaseDao.closeResource(connecton,null,rs);

        } catch (SQLException e) {
            e.printStackTrace();
        }
        return user;
    }
}

UserDao：

public interface UserDao {
    //得到要登录的用户
    public User getUser(Connection connecton, String useCode,String userCode);
}

UserServiceImpl ：

public class UserServiceImpl implements UserService{
    //业务层都调用dao层
    private UserDao userDao;
    public UserServiceImpl() {
        userDao = new UserDaoImpl();
    }
    public User login(String useCode, String password) {
        User use= null;
        Connection connecton=null;
        try {
             connecton= BaseDao.getConnection();
            use = userDao.getUser(connecton,useCode,password);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            BaseDao.closeResource(connecton,null,null);

        }
        return use;
    }

/*
    @Test
    public void test(){
       UserServiceImpl us=new UserServiceImpl();
        User admin = us.login("admin", "123");
        System.out.println(admin.toString());

    }
*/


}

UserService ：

public interface UserService {
    //用户登录
    public  User login(String userName,String password);

}

LoginServlet ：

public class LoginServlet extends HttpServlet {
//service  控制层调业务层
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String userCode = req.getParameter("userCode");
        String userPassword = req.getParameter("userPassword");
        //调用业务层查数据
        UserService user = new UserServiceImpl();
        User login = user.login(userCode, userPassword);
        if(login!=null){//查到有此人，放入session
            req.getSession().setAttribute(Constants.SUCCESS_USER,login);
            //登录成功到主页
           resp.sendRedirect("jsp/frame.jsp");
        }else{
            //未查到
            req.setAttribute("error","用户名或密码错误!");
         req.getRequestDispatcher("login.jsp").forward(req,resp);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="4.0"
         xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee
          http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         metadata-complete="true">
<!--字符编码过滤器-->
<filter>
    <filter-name>filter</filter-name>
    <filter-class>com.henry.filter.ChacterEncodingFilter</filter-class>
</filter>
    <filter-mapping>
        <filter-name>filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

<welcome-file-list>
    <welcome-file>login.jsp</welcome-file>
</welcome-file-list>
    <servlet>
        <servlet-name>login</servlet-name>
        <servlet-class>com.henry.servlet.user.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>login</servlet-name>
        <url-pattern>/login.do</url-pattern>
    </servlet-mapping>
    

</web-app>

运行：

标签：req,String,登录,管理系统,rs,smbms,user,login,public
来源： https://blog.csdn.net/weixin_44760375/article/details/120246464