Java简单页面登录

UserDao类：
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;

public class UserDao {
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    public User login(User loginUser) {
        try {
            String sql = "select * from user where username= ? and password= ?";
            User user = template.queryForObject(sql, new BeanPropertyRowMapper(User.class),
                    loginUser.getUsername(), loginUser.getPassword());

            return user;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

User类：
package cn.itcast.domain;

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 + ''' +
                '}';
    }
}

UserDaoTest类：
import cn.itcast.dao.UserDao;
import cn.itcast.domain.User;
import org.junit.Test;

public class UserDaoTest {

    @Test
    public void  testLogin(){
        User loginuser=new User();
        loginuser.setUsername("zhangsan");
        loginuser.setPassword("123");
        UserDao da=new UserDao();
        User user=da.login(loginuser);
        System.out.println(user);

    }
}

JDBCUtils工具类：
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;

public class JDBCUtils {
    private static DataSource ds;
static {
    try {
    Properties pro = new Properties();
    InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
    pro.load(is);
    ds=DruidDataSourceFactory.createDataSource(pro);
    } catch (IOException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}
    public static DataSource getDataSource() {
        return ds;
    }

    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }
}

FailServlet类：
package cn.web.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().write("登录失败");
    }

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

loginServlet类：
package cn.web.servlet;

import cn.itcast.dao.UserDao;
import cn.itcast.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 {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       //1.设置编码
        req.setCharacterEncoding("utf-8");
        
        //2.获取所有请求参数
        Map map = req.getParameterMap();
        //3.创建User对象
        User loginUser=new User();
        //使用BeanYtil封禁
        try {
            BeanUtils.populate(loginUser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
        UserDao dao=new UserDao();
        User user=dao.login(loginUser);
        if(user==null){
            //登录失败
           req.getRequestDispatcher("/FailServlet").forward(req,resp);
        }else {
            //登录成功
            req.setAttribute("user",user);
            req.getRequestDispatcher("/SuccessServlet").forward(req,resp);
        }
    }
@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    this.doPost(req,resp);
    }
}

SuccessServlet类：
import cn.itcast.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 {
        User user = (User) request.getAttribute("user");
        if (user != null) {
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("登录成功" + user.getUsername() + "");
        }
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request,response);
    }
}

配置文件：
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///数据库名
username=用户名
password=密码
# 初始化连接数量
initialSize=5
# 最大连接数量
maxActive=10
# 超时时间
maxWait=3000

层次：

 jar包：

 这里运用tomcat8.5.11

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