使用spring boot 写一个curd的类

以下是一个使用Spring Boot进行CURD操作的示例：

@Entity
@Table(name = "employee")
public class Employee {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@NotNull
private String name;

@NotNull
private String email;

public Employee() {}

public Employee(String name, String email) {
this.name = name;
this.email = email;
}

// getters and setters
}

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {}

@Service
public class EmployeeService {

@Autowired
private EmployeeRepository employeeRepository;

public List<Employee> getAllEmployees() {
return employeeRepository.findAll();
}

public Employee getEmployeeById(Long id) {
return employeeRepository.findById(id).orElse(null);
}

public Employee addEmployee(Employee employee) {
return employeeRepository.save(employee);
}

public Employee updateEmployee(Employee employee) {
Employee existingEmployee = employeeRepository.findById(employee.getId()).orElse(null);
if (existingEmployee != null) {
existingEmployee.setName(employee.getName());
existingEmployee.setEmail(employee.getEmail());
return employeeRepository.save(existingEmployee);
}
return null;
}

public void deleteEmployee(Long id) {
employeeRepository.deleteById(id);
}
}

@RestController
@RequestMapping("/api")
public class EmployeeController {

@Autowired
private EmployeeService employeeService;

@GetMapping("/employees")
public List<Employee> getAllEmployees() {
return employeeService.getAllEmployees();
}

@GetMapping("/employees/{id}")
public Employee getEmployeeById(@PathVariable Long id) {
return employeeService.getEmployeeById(id);
}

@PostMapping("/employees")
public Employee addEmployee(@RequestBody Employee employee) {
return employeeService.addEmployee(employee);
}

@PutMapping("/employees/{id}")
public Employee updateEmployee(@RequestBody Employee employee, @PathVariable Long id) {
employee.setId(id);
return employeeService.updateEmployee(employee);
}

@DeleteMapping("/employees/{id}")
public void deleteEmployee(@PathVariable Long id) {
employeeService.deleteEmployee(id);
}
}

在这个示例中，我们定义了一个Employee实体类，一个EmployeeRepository接口来操作数据库，一个EmployeeService类来实现业务逻辑，并在EmployeeController中暴露了RESTful API来处理HTTP请求。您可以根据您的需求修改这个示例，例如更改实体类的属性或更改API的路径。