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
2、创建数据库环境
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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
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<!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
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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
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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
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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
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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
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package cn.itcast.web.servlet;
import cn.itcast.dao.UserDao; import cn.itcast.domain.User; import org.apache测试数据mons.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
2、运行界面
3、输入用户名密码均正确
4、跳转到成功登录界面
5、输入用户名或密码错误时
6、跳转登录失败界面
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
原文链接：https://blog.csdn.net/weixin_44668898/article/details/107542031
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