1. 方法一

ResponseEntity<Resource> resource = restTemplate.postForEntity(reUrl, requestEntity , Resource.class);
InputStream inputStream = resource.getBody().getInputStream();
byte[] label =  this.input2byte(inputStream);
String labelStr = Base64.getEncoder().encodeToString(label);

2. 方法二

 HttpResponse<InputStream> response = Unirest.get(reUrl)
                    .basicAuth(order.getCompany().getAppUser(),order.getCompany().getAppPass())
                    .asBinary();
byte[] label =  this.input2byte(response.getBody());
//System.out.println(res);
//            byte[] label = res.getBytes(StandardCharsets.UTF_8);
String labelStr = Base64.getEncoder().encodeToString(label);

public  byte[] input2byte(InputStream inStream) throws IOException {
        ByteArrayOutputStream swapStream = new ByteArrayOutputStream();
        byte[] buff = new byte[100];
        int rc = 0;
        while ((rc = inStream.read(buff, 0, 100)) > 0) {
            swapStream.write(buff, 0, rc);
        }
        byte[] in2b = swapStream.toByteArray();
        return in2b;
    }