1.规划登录实现原理流程图
2.编写前端页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>系统登录 - 超市订单管理系统</title>
<link type="text/css" rel="stylesheet" href="${pageContext.request.contextPath }/css/style.css" />
<script type="text/javascript">
/* if(top.location!=self.location){
top.location=self.location;
} */
</script>
</head>
<body class="login_bg">
<section class="loginBox">
<header class="loginHeader">
<h1>超市订单管理系统</h1>
</header>
<section class="loginCont">
<form class="loginForm" action="${pageContext.request.contextPath }/login.do" name="actionForm" id="actionForm" method="post" >
<div class="info">${error }</div>
<div class="inputbox">
<label for="userCode">用户名：</label>
<input type="text" class="input-text" id="userCode" name="userCode" placeholder="请输入用户名" required/>
</div>
<div class="inputbox">
<label for="userPassword">密码：</label>
<input type="password" id="userPassword" name="userPassword" placeholder="请输入密码" required/>
</div>
<div class="subBtn">
<input type="submit" value="登录"/>
<input type="reset" value="重置"/>
</div>
</form>
</section>
</section>
</body>
</html>
<!--此仅仅是js，想要完整的评论留邮箱-->
3. 设置首页（登录页），将tomcat默认的index改成自己设计的首页
<!--设置欢迎页面-->
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
4.编写dao层登录用户的接口
package com.king.dao.user;
import com.king.pojo.User;
import java.sql.Connection;
import java.sql.SQLException;
//面向接口编程，接口是一种约束,要用对应类去实现
public interface UserDao {
//得到要登陆的用户
public User getLoginUser(Connection connection,String usercode) throws SQLException;
}
5，编写登录接口的实现类
package com.king.dao.user;
import com.king.dao.BaseDao;
import com.king.pojo.User;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
//实现类，实现接口的方法
public class UserDaoImpl implements UserDao{
public User getLoginUser(Connection connection, String userCode) throws SQLException {
PreparedStatement pstm=null;
ResultSet rs=null;
User user=null;
if (connection!=null){
String sql="select * from smbms_user where userCode=?";
Object[] params={userCode};
rs = BaseDao.execute(connection, pstm, rs, sql, params);
if(rs.next()){
user = new User();
user.setId(rs.getInt("id"));
user.setUserCode(rs.getString("userCode"));
user.setUserName(rs.getString("userName"));
user.setUserPassword(rs.getString("userPassword"));
user.setGander(rs.getInt("gender"));
user.setBirthday(rs.getDate("birthday"));
user.setPhone(rs.getString("phone"));
user.setAddress(rs.getString("address"));
user.setUserRole(rs.getInt("userRole"));
user.setCreatedBy(rs.getInt("createBy"));
user.setCreationDate(rs.getTimestamp("creationDate"));
user.setModifyBy(rs.getInt("modifyBy"));
user.setModifyDate(rs.getTimestamp("modifyDate"));
}
BaseDao.closeResource(null,pstm,rs);
}
return user;
}
}
6.业务层接口
package com.king.service.user;
import com.king.pojo.User;
public interface UserService {
//用户登录
public User login(String userCode,String password);
}
7业务层接口实现类
package com.king.service.user;
import com.king.dao.BaseDao;
import com.king.dao.user.UserDao;
import com.king.dao.user.UserDaoImpl;
import com.king.pojo.User;
import java.sql.Connection;
import java.sql.SQLException;
public class UserServiceImpl implements UserService{
//业务层都会调用dao层，所以要引入dao层
private UserDao userDao;
public UserServiceImpl(){
userDao=new UserDaoImpl();
}
public User login(String userCode, String password) {
Connection connection=null;
User user=null;
try {
connection= BaseDao.getConnection();
//通过业务层调用对应的dao层
user = userDao.getLoginUser(connection, userCode);
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
BaseDao.closeResource(connection,null,null);
}
return user;
}
}
8 编写servlet层，与业务层连接实现数据交互
package com.king.servlet.user;
import com.king.pojo.User;
import com.king.service.user.UserService;
import com.king.service.user.UserServiceImpl;
import com.king.util.Constants;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class LoginServlet extends HttpServlet {
//Servlet:控制层，调用业务层代码
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("LoginServlet--start...");
//获取用户名和密码
String userCode= req.getParameter("userCode");
String userPassword= req.getParameter("userPassword");
//和数据库中的密码进行对比，调用业务层来实现
UserService userService = new UserServiceImpl();
User user = userService.login(userCode, userPassword);//已经把登录的人给查出来了
if (user != null&&user.getUserPassword().equals((String) userPassword)){//找到数据，可以登录
//将用户的信息放入session中
//为什么放session，区分用户角色，比如管理员，和普通用户
req.getSession().setAttribute(Constants.USER_SESSION,user);//键值对的形式
//跳转到主页
resp.sendRedirect("jsp/frame.jsp");
}else {//查无此人无法登录
//转发会登陆页面，同时提示错误
req.setAttribute("error","用户名或密码不正确");
req.getRequestDispatcher("login.jsp").forward(req,resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
9 注册servlet
<!--Servlet-->
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>com.king.servlet.user.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login.do</url-pattern>
</servlet-mapping>
<!--字符编码过滤器-->
<filter>
<filter-name>CharacterEncodingFilter</filter-name>
<filter-class>com.king.filter.CharacterEncodingFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<!--设置欢迎页面-->
<welcome-file-list>
<welcome-file>login.jsp</welcome-file>
</welcome-file-list>
10，注销功能
package com.king.servlet.user;
import com.king.util.Constants;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class LogoutServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//移除用户的Constants.USER_SESSION
req.getSession().removeAttribute(Constants.USER_SESSION);
resp.sendRedirect("/login.jsp");//返回登陆页面
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
web配置，
<servlet>
<servlet-name>LogoutServlet</servlet-name>
<servlet-class>com.king.servlet.user.LogoutServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LogoutServlet</servlet-name>
<url-pattern>jsp/logout.do</url-pattern>
</servlet-mapping>
