请给我部门管理系统增删查询的controller层示例代码

在Java的Spring MVC框架下，一个简单的部门管理系统Controller层（通常是DepartmentController）的增删查改操作可能会像下面这样：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("/api/departments")
public class DepartmentController {

    private final DepartmentService departmentService; // 假设departmentService是一个依赖注入的服务

    @Autowired
    public DepartmentController(DepartmentService departmentService) {
        this.departmentService = departmentService;
    }

    // 创建部门
    @PostMapping
    public ResponseEntity<Department> createDepartment(@RequestBody Department department) {
        if (departmentService.create(department)) {
            return new ResponseEntity<>(department, HttpStatus.CREATED);
        } else {
            return new ResponseEntity<>("Failed to create department", HttpStatus.BAD_REQUEST);
        }
    }

    // 删除部门
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteDepartment(@PathVariable Long id) {
        if (departmentService.delete(id)) {
            return ResponseEntity.noContent().build();
        } else {
            return new ResponseEntity<>("Failed to delete department", HttpStatus.NOT_FOUND);
        }
    }

    // 查询所有部门
    @GetMapping
    public List<Department> getAllDepartments() {
        return departmentService.getAllDepartments();
    }

    // 根据ID查询单个部门
    @GetMapping("/{id}")
    public ResponseEntity<Department> getDepartmentById(@PathVariable Long id) {
        Department department = departmentService.getDepartmentById(id);
        if (department != null) {
            return new ResponseEntity<>(department, HttpStatus.OK);
        } else {
            return new ResponseEntity<>("Department not found", HttpStatus.NOT_FOUND);
        }
    }
    
    // 更新部门信息
    @PutMapping("/{id}")
    public ResponseEntity<Void> updateDepartment(@PathVariable Long id, @RequestBody Department updatedDepartment) {
        if (departmentService.update(id, updatedDepartment)) {
            return ResponseEntity.ok().build();
        } else {
            return new ResponseEntity<>("Failed to update department", HttpStatus.BAD_REQUEST);
        }
    }