管理员登录

管理员登录逻辑

1、获取前端账号和密码

2、通过账号和密码去数据库中查找

3、根据查询结果判断

查询结果为null --> 账号或密码错误

else --> 跳转到后台页面

管理员登录主程序

功能实现

实现参数查询
业务层调用

@WebServlet("/login") -- > 连接页面

代码如下：

package com.atm.servlet;

import com.atm.pojo.Manager;
import com.atm.service.AdminUserService;
import com.atm.service.impl.AdminUserServiceImpl;

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("/login")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1、获得参数
        String name = request.getParameter("name");
        String password = request.getParameter("password");
        //2、调用业务层
        AdminUserService adminUserService = new AdminUserServiceImpl();
        try {
            Manager manager = adminUserService.findManager(name, password);
            if (manager == null) {
                //登录失败
                request.setAttribute("error", "用户登录失败");
                request.getRequestDispatcher("changepage/login.jsp").forward(request, response);
            } else {
                //登陆成功,跳转到后台用户页面
                response.sendRedirect("list");
            }
        }catch (Exception exception){
            exception.printStackTrace();
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

用户信息封装

实现功能

将用户信息封装为一个对象，调用数据更加清晰

代码实现：

package com.atm.pojo;

public class Manager {
    private Integer id;
    private String name;
    private String password;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

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

业务层代码具体实现

功能实现

业务接口 --> 根据用户和密码在mysql中查询
业务实现类 --> 传入账号和密码返回用户信息

业务接口代码：

package com.atm.service;

import com.atm.pojo.Manager;

public interface AdminUserService {
    /*根据账户，密码查询管理员*/
    public Manager findManager(String name, String password) throws Exception;

}

业务实现类代码：

package com.atm.service.impl;

import com.atm.dao.AdminUserDao;
import com.atm.pojo.Manager;
import com.atm.service.AdminUserService;
/*管理员业务实现类*/
public class AdminUserServiceImpl implements AdminUserService {
    private AdminUserDao adminUserDao = new AdminUserDao();
    @Override
    public Manager findManager(String name, String password) throws Exception{
        return adminUserDao.findManager(name,password);
    }
}

用户持久层操作

功能实现

实现业务层的具体操作

在MySQL中查询账号和密码
判断否为空
null ：返回null
no null ：返回Mysql中查询的用户信息

持久层代码：

package com.atm.dao;

import com.atm.pojo.Manager;
import com.atm.utill.DBUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

//管理员用户持久层操作
public class AdminUserDao {
    /*逻辑
    * 1在mysql中根据name和password查询信息
    * 2如果存在将用户信息封装manager对象[id,name,password]返回
    * 否则返回null*/
    public Manager findManager(String name , String password) throws Exception{
        Connection connection = DBUtils.getConnection();
        PreparedStatement preparedStatement = connection.prepareStatement("select * from manage where name =? and password=?");
        preparedStatement.setString(1,name);
        preparedStatement.setString(2,password);
        ResultSet resultSet = preparedStatement.executeQuery();
        Manager manager = null;
        if (resultSet.next()){
            manager = new Manager();
            manager.setId(resultSet.getInt(1));
            manager.setName(resultSet.getString(2));
            manager.setPassword(resultSet.getString(3));
        }
        return manager;
    }
}