2022.2.23 Javaweb登录注册案例
2022/2/23 17:51:23
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代码如下：
数据库sql
-- 创建用户表
CREATE TABLE tb_user(
id int primary key auto_increment,
username varchar(20) unique,
password varchar(32)
);
-- 添加数据
INSERT INTO tb_user(username,password) values('zhangsan','123'),('lisi','234');
SELECT * FROM tb_user;
login.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>login</title>
<link href="css/login.css" rel="stylesheet">
</head>
<body>
<div id="loginDiv">
<form action="/web-demo/loginServlet" method="post" id="form">
<h1 id="loginMsg">LOGIN IN</h1>
<p>Username:<input id="username" name="username" type="text"></p>
<p>Password:<input id="password" name="password" type="password"></p>
<div id="subDiv">
<input type="submit" class="button" value="login up">
<input type="reset" class="button" value="reset">
<a href="register.html">没有账号？点击注册</a>
</div>
</form>
</div>
</body>
</html>
User.java
package com.itheima.pojo;
public class User {
private Integer id;
private String username;
private String password;
public Integer getId() {
return id;
}
public void setId(Integer 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 + '\'' +
'}';
}
}
UserMapper.java
package com.itheima.mapper;
import com.itheima.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
public interface UserMapper {
/*用户登录
*
*/
@Select("select * from tb_user where username = #{username} and password = #{password}")
User select (@Param("username") String username, @Param("password") String password);
}
UserMapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itheima.mapper.UserMapper">
</mapper>
mybatis-config.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<!--起别名-->
<typeAliases>
<package name="com.itheima.pojo"/>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql:///db1?useSSL=false&useServerPrepStmts=true"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<mappers>
<!--扫描mapper-->
<package name="com.itheima.mapper"/>
</mappers>
</configuration>
LoginServlet.java
package com.itheima.web;
import com.itheima.mapper.UserMapper;
import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
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.io.InputStream;
import java.io.PrintWriter;
/**
* @Description: TODO
* @author: scott
* @date: 2022年02月22日 10:56
*/
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//接受用户名密码
String username = req.getParameter("username");
String password = req.getParameter("password");
//调用mybatis进行查询
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user =userMapper.select(username,password);
sqlSession.close();
resp.setContentType("text/html;charset=utf-8");
PrintWriter writer = resp.getWriter();
if(user!=null){
writer.write("登录成功");
}else{
writer.write("登录失败");
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
}
报错信息：A child container failed during start
解决方案：case1.添加依赖
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
case2.检查@WebServlet("")注解中是否包含同名，有同名则不能通过编译。
如：
@WebServlet("/resp3")
@WebServlet("/resp3")
把一个更改为@WebServlet("/resp4")
注册流程
代码如下：
register.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>欢迎注册</title>
<link href="css/register.css" rel="stylesheet">
</head>
<body>
<div class="form-div">
<div class="reg-content">
<h1>欢迎注册</h1>
<span>已有帐号？</span> <a href="login.html">登录</a>
</div>
<form id="reg-form" action="/web-demo/registerServlet" method="post">
<table>
<tr>
<td>用户名</td>
<td class="inputs">
<input name="username" type="text" id="username">
<br>
<span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span>
</td>
</tr>
<tr>
<td>密码</td>
<td class="inputs">
<input name="password" type="password" id="password">
<br>
<span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
</td>
</tr>
</table>
<div class="buttons">
<input value="注 册" type="submit" id="reg_btn">
</div>
<br class="clear">
</form>
</div>
</body>
</html>
RegisterServlet.java
package com.itheima.web;
import com.itheima.mapper.UserMapper;
import com.itheima.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
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.io.InputStream;
import java.io.PrintWriter;
/**
* @Description: TODO
* @author: scott
* @date: 2022年02月23日 16:02
*/
@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doGet(req, resp);
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.接受用户数据
String username = req.getParameter("username");
String password = req.getParameter("password");
//对用户类封装
User user =new User();
//2.调用mapper 根据用户名查询用户对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User u =userMapper.selectByUsername(username);
//判断用户是否为null;
if(u == null ){
//无重名可以使用
userMapper.add(user);
//提交事务
sqlSession.commit();
resp.setContentType("text/html;charset=utf-8");
resp.getWriter().write("创建成功");
sqlSession.close();
}else{
//用户名存在
resp.setContentType("text/html;charset=utf-8");
resp.getWriter().write("用户名已存在");
sqlSession.close();
}
}
}
UserMapper.java
package com.itheima.mapper;
import com.itheima.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
public interface UserMapper {
/**用户登录
*
*/
@Select("select * from tb_user where username = #{username} and password = #{password}")
User select (@Param("username") String username, @Param("password") String password);
/**根据用户名查询用户对象
*
*/
@Select("select * from tb_user where username = #{username}")
User selectByUsername(String username);
/**注册用户
*
*/
@Insert("insert into tb_user values (null,#{username},#{password})")
void add(User user);
}
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