ResponseEntity<byte[]> responseEntity;
        try {
            responseEntity = restTemplate.exchange(
                wholeUrl,
                HttpMethod.GET,
                this.createEntity(),
                new ParameterizedTypeReference<byte[]>() {
                }
            );
        } catch (Exception e) {
            throw new BizException(ResultEnum.HTTP_ERROR);
        }

       byte[] resultByte = responseEntity.getBody();
        String resultStr = new String(resultByte, StandardCharsets.UTF_8);
　　
ObjectMapper object_mapper = new ObjectMapper();
JsonNode jsonNode = object_mapper.readValue(resultStr, JsonNode.class);
System.out.println(jsonNode.get("err"));
System.out.println(jsonNode.get("msg"));
System.out.println(jsonNode.get("data"));
System.out.println(jsonNode.get("data").get("id"));
System.out.println(jsonNode.has("data1"));

　　

    private <T> HttpEntity<T> createEntity() {
        HttpHeaders headers = new HttpHeaders();
        MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
        headers.setContentType(type);
        headers.add("Accept", MediaType.APPLICATION_JSON.toString());
        return new HttpEntity<>(headers);
    }