SpringBoot分析使用RequestBodyAdvice&ResponseBodyAdvice接口

作用：controller入参使用了@RequestBody注解获取json数据，RequestBodyAdvice才能生效。很明显，原理是aop，在读取请求body数据前后进行额外的操作。

看看RequestBodyAdvice接口源码：

public interface RequestBodyAdvice {

	
	boolean supports(MethodParameter methodParameter, Type targetType,
			Class> converterType);

	
	HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter,
			Type targetType, Class> converterType) throws IOException;

	
	Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter,
			Type targetType, Class> converterType);

	
	@Nullable
	Object handleEmptyBody(@Nullable Object body, HttpInputMessage inputMessage, MethodParameter parameter,
			Type targetType, Class> converterType);

}

Spring默认提供了接口的抽象实现类RequestBodyAdviceAdapter , 我们可以继承这个类按需实现 , 让代码更简洁一点：

public abstract class RequestBodyAdviceAdapter implements RequestBodyAdvice {

	
	@Override
	public HttpInputMessage beforeBodyRead(HttpInputMessage inputMessage, MethodParameter parameter,
			Type targetType, Class> converterType)
			throws IOException {
		return inputMessage;
	}

	
	@Override
	public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter,
			Type targetType, Class> converterType) {
		return body;
	}

	
	@Override
	@Nullable
	public Object handleEmptyBody(@Nullable Object body, HttpInputMessage inputMessage,
			MethodParameter parameter, Type targetType,
			Class> converterType) {
		return body;
	}

}

例子：

@RestControllerAdvice(annotations = {RestController.class, Controller.class})
public class baseRequestValidationAdvice extends RequestBodyAdviceAdapter {
    
    @Resource
    private SysUseronlineMapper sysUserOnlineMapper;
    
    @Resource
    private TokenService tokenService;
    
    @Override
    public boolean supports(MethodParameter methodParameter, Type targetType,
                            Class> converterType) {
        return true;
    }
    
    @Override
    public Object afterBodyRead(Object body, HttpInputMessage inputMessage, MethodParameter parameter, Type targetType,
                                Class> converterType) {
        // 基础请求入参对象，可以对token等基础参数进行校验
        baseRequest request = (baseRequest) body;
        if (body instanceof baseRequest && !(body instanceof Login/confirm/iDto) && !(body instanceof LoginIdentifyDto)) {
            if (StringUtils.isEmpty(request.getUserCode())) {
                throw new ServiceException(CommonConstant.ERROR, CommonConstant.ERROR_USERCODE_EMPTY);
            }
            if (StringUtils.isEmpty(request.getToken())) {
                throw new ServiceException(CommonConstant.ERROR, CommonConstant.ERROR_TOKEN_EMPTY);
            }
            SysUseronline sysUseronline = sysUserOnlineMapper.selectByPrimaryKey(request.getUserCode());
            if (null == sysUseronline || !request.getToken().equals(sysUserOnline.getToken())) {
                throw new ServiceException(CommonConstant.ERROR_TOKEN_INVALID,CommonConstant.ERROR_LOGOUT_ONLINE);
            }
            if (!(body instanceof LogOutDto) && StringUtils.isEmpty(request.getWarehouseCode())) {
                throw new ServiceException(CommonConstant.ERROR, CommonConstant.ERROR_WAREHOUSECODE_EMPTY);
            }
        }
        // 幂等性校验
        checkIdempotent(inputMessage, parameter);
        return body;
    }
    
    
    private void checkIdempotent(HttpInputMessage inputMessage, MethodParameter parameter){
        // 幂等性校验, 校验通过则放行, 校验失败则抛出异常, 并通过统一异常处理返回友好提示
        ApiIdempotent apiIdempotent = parameter.getMethod().getAnnotation(ApiIdempotent.class);
        if (apiIdempotent != null) {
            // 请求头中获得幂等性Id
            if(inputMessage.getHeaders().containsKey(CommonConstant.TRACTIONID)){
                // 校验等幂性，存到redis进行检验也行
                String tractionId = inputMessage.getHeaders().get(CommonConstant.TRACTIONID).get(0);
                tokenService.checkToken(tractionId);
            }else{
                throw new ServiceException(ResponseCode.ILLEGAL_ARGUMENT.getMsg());
            }
        }
    }
}

作用：controller出参返回json数据，ResponseBodyAdvice才能生效。很明显，原理都是aop，在请求返回body数据前进行额外的操作。

看看ResponseBodyAdvice接口源码：

public interface ResponseBodyAdvice {

	
	boolean supports(MethodParameter returnType, Class> converterType);

	
	@Nullable
	T beforeBodyWrite(@Nullable T body, MethodParameter returnType, MediaType selectedContentType,
			Class> selectedConverterType,
			ServerHttpRequest request, ServerHttpResponse response);

}

例子：

@RestControllerAdvice(annotations = {RestController.class, Controller.class})
public class WebControllerAdvice implements ResponseBodyAdvice {

    private Logger logger = LoggerFactory.getLogger(getClass());

    @Resource
    private TokenService tokenService;

    @ResponseBody
    @ExceptionHandler(Exception.class)
    public Result exceptionHandler(Exception e) {
        return Result.DefaultFailure(e.getMessage());
    }

    @Override
    public boolean supports(MethodParameter methodParameter, Class> aClass) {
        // controller方法上有幂等性注解ApiIdempotent才触发
        Method method = methodParameter.getMethod();
        return method.isAnnotationPresent(ApiIdempotent.class);
    }

    @Override
    public Result beforeBodyWrite(Result restResult, MethodParameter methodParameter, MediaType mediaType, Class> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
        String token = "";
        if(serverHttpRequest.getHeaders().containsKey(CommonConstant.TRACTIONID)) {
            token = serverHttpRequest.getHeaders().get(CommonConstant.TRACTIONID).get(0);
        }
        if(CommonConstant.SUCCESS.equals(restResult.getCode()) || CommonConstant.PAR_SUCCESS.equals(restResult.getCode()) ){
            // 刷新token
            int result = tokenService.updateToken(token);
            logger.info("request success update token, result:{}", result);
        } else if(CommonConstant.PICKCODE01.equals(restResult.getCode())){
            int result = tokenService.updateTokenAndMsg(token, restResult.getMessage());
            logger.info("request success update token, result:{}", result);
        } else {
            int result = tokenService.deleteToken(token);
            logger.info("request error delete token, result:{}", result);
        }
        return restResult;
    }
}