用ssm写一个注册登录接口

首先，需要在pom.xml文件中添加相关依赖：

<!-- Spring -->
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-webmvc</artifactId>
    <version>5.3.6</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-jdbc</artifactId>
    <version>5.3.6</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>

<!-- 数据库依赖 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.2.6</version>
</dependency>

然后，需要在web.xml文件中配置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>classpath:spring-mvc.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>

接下来，创建一个User实体类，用于存储用户的注册和登录信息：

public class User {
    private Integer id;
    private String username;
    private String password;
    private Date createTime;
    // 省略getters和setters
}

然后，创建一个UserService接口和其实现类UserServiceImpl，用于处理用户的注册和登录业务：

public interface UserService {
    boolean register(User user);
    User login(String username, String password);
}

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;
    
    @Override
    public boolean register(User user) {
        User existUser = userMapper.selectByUsername(user.getUsername());
        if (existUser != null) {
            return false;
        }
        user.setCreateTime(new Date());
        userMapper.insert(user);
        return true;
    }

    @Override
    public User login(String username, String password) {
        User user = userMapper.selectByUsername(username);
        if (user == null || !user.getPassword().equals(password)) {
            return null;
        }
        return user;
    }
}

其中，UserMapper是一个MyBatis的Mapper接口，用于操作数据库：

public interface UserMapper {
    void insert(User user);
    User selectByUsername(String username);
}

接下来，需要在spring-mvc.xml文件中配置相关的bean：

<context:component-scan base-package="com.example.demo"/>

<bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=utf-8"/>
    <property name="username" value="root"/>
    <property name="password" value="root"/>
</bean>

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="mapperLocations" value="classpath:mapper/*.xml"/>
</bean>

<bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
    <constructor-arg ref="sqlSessionFactory"/>
</bean>

<bean id="userMapper" class="org.mybatis.spring.mapper.MapperFactoryBean">
    <property name="mapperInterface" value="com.example.demo.mapper.UserMapper"/>
    <property name="sqlSessionTemplate" ref="sqlSessionTemplate"/>
</bean>

<bean id="userService" class="com.example.demo.service.impl.UserServiceImpl"/>

最后，创建一个UserController类，用于接收前端请求并调用UserService处理：

@Controller
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;

    @PostMapping("/register")
    @ResponseBody
    public String register(@RequestBody User user) {
        boolean result = userService.register(user);
        if (result) {
            return "success";
        } else {
            return "fail";
        }
    }

    @PostMapping("/login")
    @ResponseBody
    public String login(@RequestParam("username") String username, @RequestParam("password") String password) {
        User user = userService.login(username, password);
        if (user != null) {
            return "success";
        } else {
            return "fail";
        }
    }
}

至此，一个基本的注册登录接口就完成了，可以通过访问http://localhost:8080/user/register和http://localhost:8080/user/login来测试。