Request的登陆案例

登陆案例

要求:

    1.编写login.html登录页面
        username & password 两个输入框
    2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表
    3.使用JdbcTemplate技术封装JDBC
    4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
    5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

分析

 1.建立数据库,并建立实体类

    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
		);

 实体类User(在包com.qin.domain中)

package com.qin.domain;

/**
 * Created by SunYuqin in 2018/9/14
 * Code without comments is soulless
 * Description:
 **/

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

    public User() {
    }

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

2.建立JDBC工具类(在包com.qin.util下)

package com.qin.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;

/**
 * Created by SunYuqin in 2018/9/14
 * Code without comments is soulless
 * Description:
 **/

public class JDBCUtils {
    private static DataSource ds;

    static {
        try {
            //加载配置文件druid.properties
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //初始化DataSource对象
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    //获取datasource对象
    public static DataSource getDataSource() {
        return ds;
    }

    //获取connection对象
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }
}

3.在创建持久层com.qin.dao在UserDao类进行数据的查询

package com.qin.dao;

import com.qin.domain.User;
import com.qin.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

/**
 * Created by SunYuqin in 2018/9/14
 * Code without comments is soulless
 * Description:
 **/

public class UserDao {
    //创建jdbctemplate对象
    private JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource());

    //创建方法login
    public User login(User loginUser){
        try {
            String sql = "select * from user where username = ? and password = ?";
            User user = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (DataAccessException e) {
            //e.printStackTrace();
            return null;
        }

    }
}

4.建立loginservlet(在com.qin.servlet下)对表单的数据进行获取并操作

package com.qin.servlet;

import com.qin.dao.UserDao;
import com.qin.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 {
        //解析从html表单中获取的数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        //封装成为user对象
        User loginUser = new User();
//        loginUser.setUsername(username);
//        loginUser.setPassword(password);
        //使用beanUtils
        Map<String, String[]> parameterMap = request.getParameterMap();

        try {
            BeanUtils.populate(loginUser,parameterMap);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

        //调用UserDao
        UserDao userDao = new UserDao();
        User user = userDao.login(loginUser);

        if (user != null){
            request.setAttribute("user",user);
            request.getRequestDispatcher("/successServlet").forward(request,response);
        }else {
            request.getRequestDispatcher("/failServlet").forward(request,response);
        }

    }

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

5.建立fail以及success的servlet

//success
package com.qin.servlet;

import com.qin.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 SuccessServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取user
        User user = (User) request.getAttribute("user");
        if (user != null) {

            response.setContentType("text/html;charset=utf-8");
            response.getWriter().println("登陆成功!" + user.getUsername() + ",欢迎您");
        }
    }

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

//fail
package com.qin.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 {
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().println("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);
    }
}

6.对login.html进行action的设置,打开tomcat测试

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录案例</title>
</head>
<body>
    <form action="/day14_test/loginServlet" method="post">
        <input type="text" name="username" placeholder="请输入用户名">
        <input type="text" name="password" placeholder="请输入密码">
        <input type="submit" value="登录">
    </form>
</body>
</html>