【JavaWeb】Servlet实现网页登录功能

Myth丶恋晨 2023-03-01 09:47 16阅读 0赞

上次写了一篇JDBC工具类实现登录功能，但是只能在控制台实现输入用户名密码。这次使用了Servlet来实现登录功能，可以通过在页面上输入账号密码，然后提交表单，查询数据库，从而实现登录功能。

**1、配置文件，导入jar包**  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70]

**2、创建数据库环境**

use student;
    create table user(
    	id int primary key auto_increment,
        username varchar(32),
        password varchar(32)
    );
    
    insert into user values(null,'zhangsan','123');
    insert into user values(null,'lisi','234');

**3、在web目录下创建HTML页面**

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>登录页面</title>
    </head>
    <body>
        <form action="/day14_request/loginServlet" method="post">
            用户名：<input type="text" name="username"><br>
            密码：<input type="password" name="password"><br>
            <input type="submit" value="登录">
        </form>
    </body>
    </html>

**4、在src下编写druid.properties文件**

driverClassName=com.mysql.jdbc.Driver
    url=jdbc:mysql://localhost:3306/student
    username=root
    password=root
    maxActive=10
    maxWait=1000

**5、创建包cn.itcast.domain，创建类User**

package cn.itcast.domain;
    
    /* 用户的实体类 */
    public class User { 
        private int id;
        private String username;
        private String 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;
        }
    
        @Override
        public String toString() { 
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", password='" + password + '\'' +
                    '}';
        }
    }

**6、创建包cn.itcast.util，编写工具类JDBCUtils**

package cn.itcast.util;
    
    import com.alibaba.druid.pool.DruidDataSourceFactory;
    
    import javax.sql.DataSource;
    import java.io.IOException;
    import java.io.InputStream;
    import java.sql.Connection;
    import java.sql.SQLException;
    import java.util.Properties;
    
    /* JDBC工具类，使用Durid连接池 */
    public class JDBCUtils { 
        private static DataSource dataSource;
    
        static { 
            try { 
                //1、加载配置文件
                Properties properties = new Properties();
                InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
                properties.load(resourceAsStream);
    
                //2、初始化连接池对象
                dataSource = DruidDataSourceFactory.createDataSource(properties);
    
            } catch (IOException e) { 
                e.printStackTrace();
            } catch (Exception e) { 
                e.printStackTrace();
            }
    
    
        }
    
        /** * 获取连接池对象 */
        public static DataSource getDataSource() { 
            return dataSource;
        }
    
        /** * 获取连接Connection对象 */
        public static Connection getConnection() throws SQLException { 
            return dataSource.getConnection();
        }
    }

**7、创建包cn.itcast.dao，创建类UserDao，提供login方法**

package cn.itcast.dao;
    
    import cn.itcast.domain.User;
    import cn.itcast.util.JDBCUtils;
    import org.springframework.dao.DataAccessException;
    import org.springframework.jdbc.core.BeanPropertyRowMapper;
    import org.springframework.jdbc.core.JdbcTemplate;
    
    /** * 操作数据库中User表的类 */
    public class UserDao { 
        //声明JDBCTemplate对象共用
        private JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());
    
        /** * 登录方法 * @param loginUser 只有用户和密码 * @return user 包含用户全部信息，没有查询到，返回null */
        public User login(User loginUser) { 
    
            try { 
                //1、编写sql
                String sql = "select * from user where username = ? and password = ?";
    
                //2、调用query方法
                User user = jdbcTemplate.queryForObject(sql,
                        new BeanPropertyRowMapper<User>(User.class),
                        loginUser.getUsername(),loginUser.getPassword());
                return user;
            } catch (DataAccessException e) { 
                e.printStackTrace();//记录日志
                return null;
            }
        }
    
    }

**8、编写cn.itcast.web.servlet.LoginServlet类**

package cn.itcast.web.servlet;
    
    import cn.itcast.dao.UserDao;
    import cn.itcast.domain.User;
    import org.apache.commons.beanutils.BeanUtils;
    
    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;
    import java.lang.reflect.InvocationTargetException;
    import java.util.Map;
    
    @WebServlet("/loginServlet")
    public class LoginServlet extends HttpServlet { 
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            //1、设置编码
            request.setCharacterEncoding("utf-8");
    
            /*//2、获取请求参数 String username = request.getParameter("username"); String password = request.getParameter("password"); //3、封装对象 User loginUser = new User(); loginUser.setUsername(username); loginUser.setPassword(password);*/
    
            //2、获取所有请求参数(这里使用BeanUtils来简化操作)
            Map<String, String[]> parameterMap = request.getParameterMap();
            //3.1 创建User对象
            User loginUser = new User();
            //3.2 使用BeanUtils对象
            try { 
                BeanUtils.populate(loginUser,parameterMap);
            } catch (IllegalAccessException e) { 
                e.printStackTrace();
            } catch (InvocationTargetException e) { 
                e.printStackTrace();
            }
    
    
            //4、调用UserDao的login方法
            UserDao userDao = new UserDao();
            User user = userDao.login(loginUser);
    
            //5、判断user
            if (user == null) { 
                //登录失败
                request.getRequestDispatcher("/failServlet").forward(request,response);
            } else { 
                //登录成功
                //存储数据
                request.setAttribute("user",user);
                //转发
                request.getRequestDispatcher("/successServlet").forward(request,response);
            }
        }
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
            this.doPost(request,response);
        }
    }

**运行结果：**

1、目录结构  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 1]

2、运行界面  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 2]

3、输入用户名密码均正确  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 3]

4、跳转到成功登录界面  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 4]  
5、输入用户名或密码错误时  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 5]  
6、跳转登录失败界面  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80NDY2ODg5OA_size_16_color_FFFFFF_t_70 6]

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