Java实战之实现用户登录

一、前言

F7EF12CB-5F51-47FF-7A65-0878754EE47A.png3281DE4B-EA36-68E4-ACBB-780FE0210656.png

二、案例需求

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数据库中的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,欢迎你

5.登录失败跳转到FailServlet展示:登录失败密码错误

三、开始第一步

首先创建项目,写html页面,配置文件,jar包

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/day14/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>

85EE72B0-3880-AA14-7C22-CFDD2E2A1531.png

druid.properties配置文件:

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///day14
username=root
password=root
#初始化连接数量
initialSize=5
#最大连接数
maxActive=10
#最大等待时间
maxWait=3000
filters=stat
timeBetweenEvictionRunsMillis=60000
minEvictableIdleTimeMillis=300000
validationQuery=SELECT 1
testWhileIdle=true
testOnBorrow=false
testOnReturn=false
poolPreparedStatements=false
maxPoolPreparedStatementPerConnectionSize=200

导入jar包:

53D21500-B166-A734-268F-3E64B53EEF60.png

四、第二步

75A3C606-F0D6-0C86-E850-31CF0CDB71F1.png

创建user类:

package com.wzc.domain;
//用户的实体类
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 + '\'' +
                '}';
    }
}

五、第三步

创建jdbcUtils工具类

package com.wzc.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Druid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();
        }
//        初始化连接池
    }
    /*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UserDao类,提供login方法:

package com.wzc.dao;

import com.wzc.domain.User;
import com.wzc.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());

    /**
     * 登录方法
     * @param loginUser 只有用户名和密码
     * @return user包含用户全部数据,没有查询到则返回null
     */
    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();
//            记录日志
            return null;
        }
        }

}

编写loginServlet类:

package com.wzc.web.servlet;

import com.wzc.dao.UserDao;
import com.wzc.domain.User;
import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.ServletContext;
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 {
//       设置编码
        req.setCharacterEncoding("utf-8");
/*//       获取请求参数
        String username = req.getParameter("username");
        String password = req.getParameter("password");
//        封装user对象
        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);*/
//        获取所有请求参数
        Map<String,String[]> map = req.getParameterMap();
//        创建User对象
        User loginUser = new User();
//        使用BeanUtils封装
        try {
            BeanUtils.populate(loginUser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
//        调用UserDao的login方法
        UserDao dao = new UserDao();
        User user = dao.login(loginUser);
//        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);
    }
}

六、第四步

编写SuccessServlet类:

package com.wzc.web.servlet;

import com.wzc.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(name = "/successServlet")
public class SuccessServlet 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()+",欢迎你");
        }
    }

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

编写FailServelt类

package com.wzc.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 {
//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,用户名和密码错误");
    }

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

输入错误的账号和密码

1760C7E0-8868-517B-677B-44F059285F86.png

登录失败提示:

FC08353B-2D8D-4E24-B05E-515B70CA2293.png

七、总结

login.html中form表单的action路径写法:虚拟路径+Servlet的资源路径

**BeanUtils工具类,简化数据封装:**用于封装javaBean

javaBean:标准的java类 功能:封装数据

有一下四点要求:

1.类必须被public修饰

2.必须提供空参的构造器

3.成员变量必须使用private修饰

4.提供公共setter和getter方法

属性:setter和getter方法截取后的产物例如:getUsername()–>Username–>username可见username就是属性方法有三种:

1.setProperty()2.getProperty()3.populate(Object obj , Map map):将map集合的键值对信息,封装到对应的JavaBean对象中(最常用)

package com.wzc.test;

import com.wzc.domain.User;
import org.apache.commons.beanutils.BeanUtils;
import org.junit.Test;

import java.lang.reflect.InvocationTargetException;

public class BeanUtilsTest {
    @Test
    public void test(){
        User user = new User();
        try {
            BeanUtils.setProperty(user,"hehe","male");
            System.out.println(user);
            String gender = BeanUtils.getProperty(user, "hehe");
            System.out.println(gender);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }
}
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