spring数据库编程实现用户登录功能

以下是使用Spring框架实现用户登录功能的示例代码：

1. 创建User类，表示用户实体

public class User {
    private String username;
    private String password;
    // getter and setter methods
}

2. 创建UserService接口，定义用户服务接口方法

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

3. 创建UserDao接口，定义用户数据访问接口方法

public interface UserDao {
    User findUserByUsername(String username);
}

4. 创建UserServiceImpl类，实现UserService接口

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserDao userDao;

    @Override
    public boolean login(String username, String password) {
        User user = userDao.findUserByUsername(username);
        if (user == null) {
            return false;
        }
        return user.getPassword().equals(password);
    }
}

5. 创建UserDaoImpl类，实现UserDao接口

@Repository
public class UserDaoImpl implements UserDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public User findUserByUsername(String username) {
        String sql = "SELECT * FROM user WHERE username=?";
        return jdbcTemplate.queryForObject(sql, new Object[]{username}, new RowMapper<User>() {
            @Override
            public User mapRow(ResultSet resultSet, int i) throws SQLException {
                User user = new User();
                user.setUsername(resultSet.getString("username"));
                user.setPassword(resultSet.getString("password"));
                return user;
            }
        });
    }
}

6. 在Spring配置文件中配置数据源和JdbcTemplate

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost:3306/test" />
    <property name="username" value="root" />
    <property name="password" value="password" />
</bean>

<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
    <property name="dataSource" ref="dataSource" />
</bean>

7. 在Spring配置文件中配置UserService和UserDao的实现类

<bean id="userService" class="com.example.service.impl.UserServiceImpl">
    <property name="userDao" ref="userDao" />
</bean>

<bean id="userDao" class="com.example.dao.impl.UserDaoImpl">
    <property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>

8. 在Controller中调用UserService的login方法实现用户登录

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

    @RequestMapping(value = "/login", method = RequestMethod.POST)
    public String login(@RequestParam String username, @RequestParam String password, Model model) {
        if (userService.login(username, password)) {
            return "success";
        } else {
            model.addAttribute("errorMsg", "用户名或密码错误");
            return "login";
        }
    }
}

以上就是使用Spring框架实现用户登录功能的示例代码。需要注意的是，示例代码中使用的是JdbcTemplate对数据库进行访问，实际项目中可以使用MyBatis等ORM框架。