java與外部接口通信之restTemplate的使用

restTemplate的使用

此處為post方式

ObjectMapper可以解析傳回資料

public Result sendEamil(Email email) {
		ObjectMapper mapper = new ObjectMapper();
		// 将實體類轉換成json資料
		String jsonData = null;
		try {
			jsonData = mapper.writeValueAsString(email);
			// jsonData = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(email);
		} catch (JsonProcessingException e) {
			log.error(e.getMessage());
		}

		// RestTemplate
		RestTemplate client = new RestTemplate();

		// 建立請求頭
		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> entity = new HttpEntity<>(jsonData, headers);

		// 發送請求得到響應資料
		String res = client.postForObject(URL, entity, String.class);

		Result result = null;
		try {
			// JSON字元串轉HashMap
			result = mapper.readValue(res, Result.class);
		} catch (IOException e) {
			log.error(e.getMessage());
		}
		logService.addMailLog(email, result);
		return result;
	}
           

另一種解析

public static RestTemplate getInstance(String charset) {
        RestTemplate restTemplate = new RestTemplate();
        List<HttpMessageConverter<?>> list = restTemplate.getMessageConverters();
        for (HttpMessageConverter<?> httpMessageConverter : list) {
            if(httpMessageConverter instanceof StringHttpMessageConverter) {
                ((StringHttpMessageConverter) httpMessageConverter).setDefaultCharset(Charset.forName(charset));
                break;
            }
        }
        return restTemplate;
    }
//傳入token和參數
public static Result post(String token,Map<String, Object> map) {
        RestTemplate restTemplate = getInstance("UTF-8");
        String url = "localhost:8888";
        HttpHeaders requestHeaders = new HttpHeaders();
        requestHeaders.add("token", token);
        HttpEntity<String> requestEntity = new HttpEntity<>(JSONObject.toJSONString(map),requestHeaders);
        ResponseEntity<String> exchange = restTemplate.exchange(url, HttpMethod.POST, requestEntity, String.class);
        String returnString = exchange.getBody();
        //解析字元串
        JSONObject parseObject = JSON.parseObject(returnString);
        Iterator<Entry<String, Object>> it = parseObject.entrySet().iterator();
        Result r = new Result();
        while (it.hasNext()) {
            Map.Entry<String, Object> entry = it.next();
            //entry.getKey和getValue擷取鍵值對，并放到Map裡
        }
        return r;
    }