Request_获取ServletContext和登录案例需求代码实现

获取ServletContext：ServletContext getServletContext();

@WebServlet("/requestDemo5")
public class requestDemo5 extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ServletContext servletContext = req.getServletContext();
        System.out.println(servletContext);

    }

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 登录案例_需求

  1.编写login.html登录页面，username & password 两个输入框

  2.使用Druid数据库连接池技术，操作mysql，day14数据库中user表

  3.使用JdbcTemplate技术封装JDBC

  4.登录成功跳转到SuccessServlet展示：登录成功！用户名，欢迎您

  5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

 

 

 

 

创建实体类：

package com.itheima.domain;

public class User {

    private int id;
    private String username;
    private String password;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

创建UserDao编写方法

 private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());


    /**
     * 登录方法
     * @param loginUser
     * @return
     */
    public User login(User loginUser){

        try {
            String sql = "select * from user where username = ? and password = ?";
            User user = template.queryForObject(sql, new BeanPropertyRowMapper<User>
                    (User.class), loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();
            return null;
        }
    }

创建JDBCUtil

private static DataSource ds;

    static {
        try {
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

           ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    public static DataSource getDataSource(){
        return ds;
    }

    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

导入druid.properties文件

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///day14
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000

导入lib目录

 

 

 

创建test测试

  @Test
    public void tets(){
        User user = new User();
        user.setUsername("ss");
        user.setPassword("123");

        UserDao userDao = new UserDao();
        User login = userDao.login(user);

        System.out.println(login);
    }

 

创建:failServlet.class

@WebServlet("/failServlet")
public class failServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        resp.getWriter().write("登录失败，用户名密码错误");
    }

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

 

 

创建 LoginServlet.class

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("utf-8");

        String username = req.getParameter("username");
        String password = req.getParameter("password");

        User user = new User();
        user.setUsername(username);
        user.setPassword(password);

        UserDao userDao = new UserDao();
        User login = userDao.login(user);

        if (login == null){
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        }else {
            req.setAttribute("user",user);
            req.getRequestDispatcher("/successServlet").forward(req,resp);
        }

    }

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

 

 

创建 successServlet.class

@WebServlet("/successServlet")
public class successServlet extends HttpServlet {

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

        User user = (User) req.getAttribute("user");

        if (user!=null){
            resp.setContentType("text/html;charset=utf-8");
            resp.getWriter().write("登录成功!"+user.getUsername()+"欢饮您");
        }
        resp.getWriter().write("登录成功!");
    }

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

 

 

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