解决方法：
设置httpheader的时候，加上utf-8编码
String body = "中文你好";
RestTemplate restTemplate = new RestTemplate();
HttpHeaders headers = new HttpHeaders();
MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
headers.setContentType(type);
HttpEntity<String> formEntity = new HttpEntity<String>(body, headers);