创建请求
创建请求头：
Map<String, String> requestBody = new HashMap<>();
requestBody.put("userId", userId);
requestBody.put("userName", userName);
创建请求体：
HttpHeaders requestHeader = new HttpHeaders();
requestHeader.add("cookie", "cookie");
requestHeader.add("userInfo", "{userId:101,userName:userName}");
创建请求方式：
HttpEntity<Map<String, String>> httpEntity = new HttpEntity<>(requestHeader);
RestTemplate restTemplate = new RestTemplate();
POST请求
restTemplate发送POST请求时可以通过如下方法获取ResponseEntity：
ResponseEntity responseEntity = restTemplate.postForEntity(url, httpEntity, JSONObject.class);
或用以下方法获取jsonObject：
JSONObject jsonObject = restTemplate.postForObject(url, httpEntity, JSONObject.class);
GET请求
GET请求没有相应的方法，只能用exchange方法获取ResponseEntity：
ResponseEntity<JSONObject> responseEntity = restTemplate.exchange(url, HttpMethod.GET, httpEntity, JSONObject.class, requestBody);
若出现如下报错：
Not enough variables available to expand
则是因为RestTemplate认为大括号{}为占位符，需要将请求头中的{userId:101,userName:userName}改为{\"userId\":\"101\",\"userName\":\"userName\"}
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