java登陆小案例

java登陆小案例

src/cn.dao/UserDao

package cn.dao;

import cn.test.User;
import cn.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

//操作数据库中User表的类
public class UserDao {
//    声明JDBCTemplate对象共用
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
//    声明JDBCTemplate对象共用login

    public User login(User loginUser){
        try {
//        编写sql
            String sql = "select * from user where username = ? and password = ?";
//        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();
            return null;
        }
    }
}

src/cn.test/User

package cn.test;

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

src/cn.test1/UserDaoTest

package cn.test1;

import cn.dao.UserDao;
import cn.test.User;
import org.junit.Test;

public class UserDaoTest {
    @Test
    public void testLogin(){
        User loginuser = new User();
        loginuser.setUsername("test1");
        loginuser.setPassword("test1");

        UserDao dao = new UserDao();
        User user = dao.login(loginuser);
        System.out.println(user);
    }
}

src/cn.util/JDBCUtils

package cn.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;

/*
* JDBC工具类 使用Durid连接池
*/
public class JDBCUtils {
    private static DataSource ds;

    static {
        try {
//        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);
//            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();
    }
}

src/cn.web.servlet/FailServlet

package cn.web.servlet;

import cn.test.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("/failServlet")
public class FailServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        User user = (User) req.getAttribute("user");
        if (user==null){
            resp.setContentType("text/html;charset=utf-8");
            resp.getWriter().write("登录失败，用户名或密码错误");
        }
    }
}

src/cn.web.servlet/LoginServlet

package cn.web.servlet;

import cn.dao.UserDao;
import cn.test.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 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);
        Map<String,String[]> map = req.getParameterMap();
        User loginUser = new User();
//       使用BeanUtils
        try {
            BeanUtils.populate(loginUser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
//        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);
    }
}

src/cn.web.servlet/SuccessServlet

package cn.web.servlet;

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

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        User user = (User) req.getAttribute("user");
        if (user!=null){
            resp.setContentType("text/html;charset=utf-8");
            resp.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");
        }
    }
}

src/druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///java_login
username=root
password=yf8629976
initialSize=5
maxActive=10
maxWait=3000

web/login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form action="/webthree_war_exploded/loginServlet" method="post">
        用户名:<input type="text" name="username"> <br>
        密码:<input type="password" name="password"><br>
        <input type="submit" value="登录">
    </form>
</body>
</html>