sentinel异常处理机制

1、自动识别出来的web接口

会走BlockExceptionHandler，可自定义，例如：

@Component
public class SentinelBlockExceptionHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, String s,
        BlockException e) throws Exception {
        tooFrequencyResponse(httpServletResponse);
    }

    public void tooFrequencyResponse(HttpServletResponse response) throws IOException {
        response.setContentType("application/json;charset=UTF-8");
        response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value()); // 429状态码

        CommonResult<?> result = CommonResult.failResult(8001, "服务器繁忙，请稍后重试");
        String jsonString = JSONUtil.toJsonStr(result);
        response.getWriter().write(jsonString);
    }
}

在项目中加入此类即可生效

2、@SentinelResource标记的资源

会依次去找@SentinelResource注解里面配置的blockHandler，fallback，defaultFallback，根据先后顺序找到即对应处理，如果都未配置，则返回Springboot的默认处理

统一处理：

@ExceptionHandler({UndeclaredThrowableException.class})
public CommonResult<?> flowExceptionHandler(UndeclaredThrowableException e) {
    log.error("UndeclaredThrowableException: ", e);
    return CommonResult.failResult(CommonErrorInfo.code_8001,"服务器繁忙，请稍后重试");
}

3、openfeign调用的资源

会根据设置的fallback来返回异常，如果未设置则返回Springboot的默认处理