调用第三方api 若是服务返回状态码不为200，默认会执行DefaultResponseErrorHandler
异常处理

@Override
	public void handleError(ClientHttpResponse response) throws IOException {
		HttpStatus statusCode = getHttpStatusCode(response);
		switch (statusCode.series()) {
			case CLIENT_ERROR:
				throw new HttpClientErrorException(statusCode, response.getStatusText(),
						response.getHeaders(), getResponseBody(response), getCharset(response));
			case SERVER_ERROR:
				throw new HttpServerErrorException(statusCode, response.getStatusText(),
						response.getHeaders(), getResponseBody(response), getCharset(response));
			default:
				throw new RestClientException("Unknown status code [" + statusCode + "]");
		}
	}


	判断是否异常
	protected boolean hasError(HttpStatus statusCode) {
		return (statusCode.series() == HttpStatus.Series.CLIENT_ERROR ||
				statusCode.series() == HttpStatus.Series.SERVER_ERROR);
	}

当响应http状态码为401时，使用e.getResponseBodyAsString()无法获取响应消息

	try{
      ......
    }catch (HttpClientErrorException e) {
                String resBody = e.getResponseBodyAsString();
                log.info("客户端异常返回:{}", resBody);
                return new ResponseEntity<>(JSON.parseObject(resBody, res), e.getStatusCode());
            } 

这与初始化RestTemplate设置的RequestFactory有关，默认RequestFactory是SimpleClientHttpRequestFactory，修改为HttpComponentsClientHttpRequestFactory，就可以了

    @Bean
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());
        return  restTemplate;
    }