登录案例-代码实现

登录案例-代码实现

　　1. 创建项目，导入html页面，配置文件，jar包

　　2. 创建数据库环境

CREATE DATABASE day14;
USE day14;
CREATE TABLE USER(

id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32) UNIQUE NOT NULL,
PASSWORD VARCHAR(32) NOT NULL
);

创建包cn.itcast.domain,创建类User

package com.example.day_13_test.domain;

public class User {
    private int id;
    private String username;
    private String password;

    public User(int id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }

    public User() {
    }

    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 + '\'' +
                '}';
    }
}

创建包cn.itcast.util,编写工具类JDBCUtils

package com.example.day_13_test.utils;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import javax.xml.crypto.Data;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
public class JDBCUtils {
    private static DataSource ds ;

    static {

        try {
            //1.加载配置文件
            Properties pro = new Properties();
            //使用ClassLoader加载配置文件，获取字节输入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //2.初始化连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接池对象
     */
    public static DataSource getDataSource(){
        return ds;
    }
    /**
     * 获取连接Connection对象
     */
    public static Connection getConnection() throws SQLException {
        return  ds.getConnection();
    }
}

创建包cn.itcast.dao,创建类UserDao,提供login方法

package com.example.day_13_test.dao;

import com.example.day_13_test.domain.User;
import com.example.day_13_test.utils.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

public class UserDao {
    //声明JDBCTemplate对象共用
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    /**
     * 登录方法
     * @param loginUser 只有用户名和密码
     * @return user包含用户全部数据,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 = template.queryForObject(sql,
                    new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (DataAccessException e) {
            e.printStackTrace();//记录日志
            return null;
        }
    }
}

编写cn.itcast.web.servlet.LoginServlet类

package com.example.day_13_test.servlet;


import com.example.day_13_test.dao.UserDao;
import com.example.day_13_test.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 {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1.设置编码
        req.setCharacterEncoding("utf-8");
        //2.获取请求参数
        String username = req.getParameter("username");
        String password = req.getParameter("password");
        //3.封装user对象
        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);

        //4.调用UserDao的login方法
        UserDao dao = new UserDao();
        User user = dao.login(loginUser);

        //5.判断user
        if(user == null){
            //登录失败
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        }else{
            //登录成功
            //存储数据
            req.setAttribute("user",user);
            //转发
            req.getRequestDispatcher("/successServlet").forward(req,resp);
        }

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}

编写FailServlet和SuccessServlet类

package com.example.day_13_test.servlet;

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 {
        //给页面写一句话

        //设置编码
        response.setContentType("text/html;charset=utf-8");
        //输出
        response.getWriter().write("登录失败，用户名或密码错误");

    }

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

package com.example.day_13_test.servlet;


import com.example.day_13_test.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 SuccessServle  extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取request域中共享的user对象
        User user = (User) request.getAttribute("user");

        if (user != null) {
            //给页面写一句话

            //设置编码
            response.setContentType("text/html;charset=utf-8");
            //输出
            response.getWriter().write("登录成功！" + user.getUsername() + ",欢迎您");
        }
    }
}