写基于ssm框架注册登录的代码

好的，我来为你写一份基于SSM框架实现注册登录的代码。

首先，我们需要在pom.xml文件中添加相关依赖：

<dependencies>
   <!-- Spring -->
   <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.3.5</version>
   </dependency>
   <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-jdbc</artifactId>
      <version>5.3.5</version>
   </dependency>
   <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-tx</artifactId>
      <version>5.3.5</version>
   </dependency>
   <!-- MyBatis -->
   <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.6</version>
   </dependency>
   <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis-spring</artifactId>
      <version>2.0.6</version>
   </dependency>
   <!-- 数据库驱动 -->
   <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.23</version>
   </dependency>
   <!-- JSP & Servlet -->
   <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
      <scope>provided</scope>
   </dependency>
   <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.3</version>
      <scope>provided</scope>
   </dependency>
   <!-- JSTL -->
   <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
   </dependency>
</dependencies>

接下来，我们需要在web.xml文件中配置Spring的前端控制器DispatcherServlet：

<servlet>
   <servlet-name>dispatcherServlet</servlet-name>
   <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
   <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>/WEB-INF/spring-servlet.xml</param-value>
   </init-param>
   <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
   <servlet-name>dispatcherServlet</servlet-name>
   <url-pattern>/</url-pattern>
</servlet-mapping>

在src/main/resources目录下创建spring-servlet.xml文件，配置Spring相关的配置信息和控制器：

<!-- 配置数据源 -->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
   <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
   <property name="url" value="jdbc:mysql://localhost:3306/test?useSSL=false&amp;serverTimezone=UTC&amp;useUnicode=true&amp;characterEncoding=utf-8"/>
   <property name="username" value="root"/>
   <property name="password" value="123456"/>
</bean>

<!-- 配置MyBatis -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
   <property name="dataSource" ref="dataSource"/>
   <property name="typeAliasesPackage" value="com.example.model"/>
</bean>

<!-- 配置Mapper扫描 -->
<mybatis-spring:scan base-package="com.example.dao"/>

<!-- 配置事务 -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
   <property name="dataSource" ref="dataSource"/>
</bean>

<!-- 配置SpringMVC -->
<context:component-scan base-package="com.example"/>
<mvc:annotation-driven/>

<!-- 配置视图解析器 -->
<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
   <property name="prefix" value="/WEB-INF/views/"/>
   <property name="suffix" value=".jsp"/>
</bean>

我们还需要在src/main/webapp/WEB-INF/views目录下创建register.jsp和login.jsp页面，分别用于用户注册和登录。

接下来，我们编写控制器和DAO接口的实现类。

UserController.java：

@Controller
public class UserController {
   @Autowired
   private UserService userService;

   @RequestMapping(value = "/register", method = RequestMethod.GET)
   public String showRegisterPage(Model model) {
      model.addAttribute("user", new User());
      return "register";
   }

   @RequestMapping(value = "/register", method = RequestMethod.POST)
   public String registerUser(@ModelAttribute("user") User user, BindingResult result, Model model) {
      if (result.hasErrors()) {
         return "register";
      }

      if (userService.isUserNameExist(user.getUserName())) {
         model.addAttribute("error", "用户名已存在");
         return "register";
      }

      userService.addUser(user);
      return "redirect:/login";
   }

   @RequestMapping(value = "/login", method = RequestMethod.GET)
   public String showLoginPage(Model model) {
      model.addAttribute("user", new User());
      return "login";
   }

   @RequestMapping(value = "/login", method = RequestMethod.POST)
   public String loginUser(@ModelAttribute("user") User user, BindingResult result, HttpSession session, Model model) {
      if (result.hasErrors()) {
         return "login";
      }

      if (!userService.isUserNameExist(user.getUserName())) {
         model.addAttribute("error", "用户名不存在");
         return "login";
      }

      User dbUser = userService.getUserByUserName(user.getUserName());
      if (dbUser.getPassword().equals(user.getPassword())) {
         session.setAttribute("user", dbUser);
         return "redirect:/home";
      } else {
         model.addAttribute("error", "密码错误");
         return "login";
      }
   }

   @RequestMapping(value = "/logout", method = RequestMethod.GET)
   public String logoutUser(HttpSession session) {
      session.invalidate();
      return "redirect:/login";
   }
}

UserService.java：

@Service
@Transactional
public class UserServiceImpl implements UserService {
   @Autowired
   private UserMapper userMapper;

   @Override
   public boolean isUserNameExist(String userName) {
      User user = userMapper.selectByUserName(userName);
      return user != null;
   }

   @Override
   public void addUser(User user) {
      userMapper.insert(user);
   }

   @Override
   public User getUserByUserName(String userName) {
      return userMapper.selectByUserName(userName);
   }
}

UserMapper.java：

public interface UserMapper {
   void insert(User user);
   User selectByUserName(String userName);
}

User.java：

public class User {
   private int id;
   private String userName;
   private String password;
   private String email;

   // getter & setter methods
}

最后，我们需要在src/main/resources目录下创建mybatis-config.xml文件，配置MyBatis的相关信息：

<configuration>
   <settings>
      <setting name="mapUnderscoreToCamelCase" value="true"/>
   </settings>
</configuration>

好了，以上就是基于SSM框架实现注册登录的代码。