Spring中@Service注解的作用与@Controller和@RestController之间区别

@Service
@Primary
public class YtDesignInfoServiceImpl implements YtDesignInfoService {
    @Autowired
    private YtDesignInfoMapper ytDesignInfoMapper;
    @Override
    public YtDesignInfo getItem(String GCID){
        YtDesignInfoExample example = new YtDesignInfoExample();
        YtDesignInfoExample.Criteria criteria = example.createCriteria();
        criteria.andLProjectidEqualTo(GCID);
        List<YtDesignInfo> ytDesignInfos = ytDesignInfoMapper.selectByExample(example);
        return ytDesignInfos.get(0);
    }
}

@RestController
@Api(tags = "YantuController", value = "岩土管理")
@RequestMapping("/yantu")
public class YanTuController {
    @Autowired
    private YtDesignInfoService ytDesignInfoService;
    @Autowired
    private YtDuanmianService ytDuanmianService;
    @ApiOperation(value = "新增岩土成果的工程信息")
    @PostMapping(value = "/addYanTuItemInfo")
    public CommonResult<?> addYanTuInfo(Principal principal, @Validated YtDesignInfo ytDesignInfo) {
        if (principal == null) {
            return CommonResult.unauthorized(null);
        }
        int i = ytDesignInfoService.addItem(ytDesignInfo);

        if (i>0) {
            return CommonResult.success("上传成功");
        } else {
            return CommonResult.failed("上传失败");
        }
    }
}

@Controller
public class FileUploadController {
	//跳转到上传文件的页面
	//在对应的方法上，视图解析器可以解析return 的jsp,html页面，并且跳转到相应页面。
	@RequestMapping(value="/gouploadimg", method = RequestMethod.GET)
	public String goUploadImg() {
		//跳转到 templates 目录下的 uploadimg.html
		return "uploadimg";
	}
	//处理文件上传
	//若返回json等内容到页面，则需要加@ResponseBody注解
	//如果返回的是String类型，则仍然是String。
	@RequestMapping(value="/testuploadimg", method = RequestMethod.POST)
	@ResponseBody
	public String uploadImg(@RequestParam("file") MultipartFile file,HttpServletRequest request) {
		System.out.println("调用文件上传方法");
		String contentType = file.getContentType();
		String fileName = file.getOriginalFilename();	
		return filename;
	}
}

@RestController /* @Controller + @ResponseBody*/
public class HospitalController {
    //注入Service服务对象
    @Autowired
    private HospitalService hospitalService;
    /**
     * 查询所有医院信息（未分页）
     */
	//@RestController注解可以直接返回json数据
	//@Controller注解无法返回json数据
    @RequestMapping(value = "findAllHospital",method = RequestMethod.GET)
    public  List<Hospital> findAllHospital(){
        List<Hospital> hospitalList= hospitalService.findAllHospital();
        return hospitalList;
    }
}