Java实现用户登录Demo

ゞ浴缸里的玫瑰 2022-02-15 10:59 298阅读 0赞

## 一、环境 ##

工具：Idea，mysql，Jdk9

## 二、工程目录 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 1]

## 三、代码编写 ##

**1、数据库表 \_ user**

CREATE TABLE user(
    id INT,
    username VARCHAR(10),
    password VARCHAR(10)
    );
    ALTER TABLE user MODIFY id INT PRIMARY KEY AUTO_INCREMENT;
    ALTER TABLE user MODIFY username VARCHAR(10) NOT NULL;
    ALTER TABLE user MODIFY password VARCHAR(10) NOT NULL;

**2、JDBC工具类 \_ JDBCUtils**

package com.mollen.util;
    
    import com.alibaba.druid.pool.DruidDataSourceFactory;
    
    import javax.sql.DataSource;
    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.util.Properties;
    
    /**
     * @ClassName:      JDBCUtils
     * @Auther:         Mollen
     * @CreateTime:     2018-09-23  10:18:14
     * @Description:    JDBCUtils 数据库连接工具类
     */
    public class JDBCUtils {
    
        /**
         * 1.定义成员变量datasource
         */
        private static DataSource ds;
    
        /**
         * 2.加载数据源
         */
        static {
            try {
                Properties pro = new Properties();
                pro.load(JDBCUtils.class.getClassLoader().getResourceAsStream("Druid.properties"));
                ds = DruidDataSourceFactory.createDataSource(pro);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        /**
         * 3.获取连接池对象
         * @return
         */
        public static DataSource getDatasource(){
            return ds;
        }
    
        /**
         * 4.获取连接池Connection对象
         * @return
         * @throws SQLException
         */
        public static Connection getConnection() throws SQLException {
            return ds.getConnection();
        }
    
        /**
         * 5.释放资源
         * @param st
         * @param conn
         */
        public static void close(PreparedStatement st, Connection conn) {
            close(null, st, conn);
        }
    
        /**
         * 5.释放资源重载方法
         * @param rs
         * @param st
         * @param conn
         */
        public static void close(ResultSet rs, PreparedStatement st, Connection conn) {
            if (rs != null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (st != null) {
                try {
                    st.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
            if (conn != null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }
    }

**3、实体类 \_ User**

package com.mollen.domain;
    
    /**
     * @ClassName:      User
     * @Auther:         Mollen
     * @CreateTime:     2018-09-23  10:12:41
     * @Description:
     *                  User实体类
     */
     
    public class User {
    
        private String userName;
        private String password;
    
        public User() {
        }
    
        public User(String userName, String password) {
            this.userName = userName;
            this.password = password;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "userName='" + userName + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    
        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;
        }
    }

**4、用户操作类 \_ UserDao**

package com.mollen.dao;
    
    import com.mollen.domain.User;
    import com.mollen.util.JDBCUtils;
    import org.springframework.jdbc.core.BeanPropertyRowMapper;
    import org.springframework.jdbc.core.JdbcTemplate;
    
    /**
     * @ClassName: 	UserDao
     * @Auther:	Mollen
     * @CreateTime: 2018-09-23  10:17:31
     * @Description: UserDao类操作user数据
     */
    public class UserDao {
    
        private JdbcTemplate jtl = new JdbcTemplate(JDBCUtils.getDatasource());
    
        public User login(User loginUser) {
            try {
                String sql = "SELECT * FROM user WHERE username=? and password = ?";
                User user = jtl.queryForObject(
                        sql, new BeanPropertyRowMapper<User>(User.class),
                        loginUser.getUserName(), loginUser.getPassword());
                return user;
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }
    
        }
    }

**5、Servlet类**

1.登陆Serevlet \_ LoginServlet

package com.mollen.web;
    
    import com.mollen.dao.UserDao;
    import com.mollen.domain.User;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           this.doGet(request,response);
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            request.setCharacterEncoding("utf-8");
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            User loginUser = new User(username,password);
    
            UserDao userDao = new UserDao();
            User user = userDao.login(loginUser);
    
            if(user==null){
                request.getRequestDispatcher("/failServlet").forward(request,response);
            }else{
                request.setAttribute("user",user);
                request.getRequestDispatcher("/successServlet").forward(request,response);
            }
        }
    }

2.失败跳转Servlet类 \_ FailServlet

package com.mollen.web;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/failServlet")
    public class FailServlet extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("登陆失败! 用户名或者密码错误!");
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request,response);
        }
    }

3.成功跳转 \_ ServletSuccessServlet

package com.mollen.web;
    
    import com.mollen.domain.User;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @WebServlet("/successServlet")
    public class SuccessServlet extends HttpServlet {
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            User user = (User) request.getAttribute("user");
            if (user != null) {
                response.setContentType("text/html;charset=utf-8");
                response.getWriter().write("登陆成功!" + user.getUserName() + ",欢迎你!");
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request, response);
        }
    }

## 实现效果如下： ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 2]

原文：[https://blog.csdn.net/mollen/article/details/82822801][https_blog.csdn.net_mollen_article_details_82822801]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70]: /images/20220215/02f24161c7c34beca6319e538725e34d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 1]: /images/20220215/bda945ae332c414cb9a8eeddf624abd0.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nMTUwMTE0_size_16_color_FFFFFF_t_70 2]: /images/20220215/efcbdbceb845420e823447a7fd36e057.png
[https_blog.csdn.net_mollen_article_details_82822801]: https://blog.csdn.net/mollen/article/details/82822801