●exchange方法提供統一的方法模板進行四種請求：POST,PUT,DELETE,GET

(1)POST請求

String reqJsonStr = "{\"code\":\"testCode\", \"group\":\"testGroup\",\"content\":\"testContent\", \"order\":1}";
HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> entity = new
 
 HttpEntity<String>(reqJsonStr,headers);
ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL, HttpMethod.POST, entity, Map.class);

(2)PUT請求

String reqJsonStr = "{\"id\":227,\"code\":\"updateCC\", \"group\":\"UPDATE\",\"content\":\"updateCT\", \"order\":9}";
HttpHeaders headers 
 
= new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<String> entity = new HttpEntity<String>(reqJsonStr,headers);
ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL, HttpMethod.PUT, entity, Map.class);

(3)DELETE請求

ResponseEntity<Map> resp = restTemplate.exchange(DIC_DATA_URL + "?id={id}", HttpMethod.DELETE, null
 
, Map.class, 227);

(4)GET請求

ResponseEntity<String> results = restTemplate.exchange(url,HttpMethod.GET, null, String.class, params);

說明：1）url: 請求地址；
     2）method: 請求類型(如：POST,PUT,DELETE,GET)；
     3）requestEntity: 請求實體，封裝請求頭，請求內容
     4）responseType: 響應類型，根據服務接口的返回類型決定
     5）uriVariables: url中參數變量值

Spring RestTemplate 之exchange方法