HttpHeaders headers = new HttpHeaders();
MediaType type = MediaType.parseMediaType("application/json; charset=UTF-8");
headers.setContentType(type);
headers.add("Accept", MediaType.APPLICATION_JSON.toString());
HttpEntity<String> requestEntity = new HttpEntity<String>((new JSONObject()).toString(), headers);
restTemplate.getMessageConverters().set(1,new StringHttpMessageConverter(StandardCharsets.UTF_8));
ResponseEntity<String> exchange = restTemplate.exchange(url, HttpMethod.GET, requestEntity, String.class);

根据编码确定

StandardCharsets.UTF_8 的不同。

http请求中文乱码问题