RestTemplate时出现RestClientException原因和解决方法

RestTemplate时出现RestClientException的解决办法

1.先来看一下报错吧

2.我的写法

Map<String, Object> params = paramRequest();
        params.put("unionId", unionId);
        params.put("userId", userId);
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        HttpEntity<Map<String, Object>> requestEntity = new HttpEntity<>(params, httpHeaders);
        JSONObject stoResult = restTemplate.postForObject(userCenterUrl + BIND, requestEntity, JSONObject.class);

3.对方的接口要求的ContentType是APPLICATION_FORM_URLENCODED，表单提交但是HttpEntity中用map、hashmap 都报错，都不可以。
只有改成multivalueMap才可以。如下：

String timestamp = SDF.format(new Date());
        MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
        params.add("timestamp", timestamp);
        params.add("sign", SignUtils.signRequest(timestamp, baseAppsecret));
        params.add("appKey", baseAppkey);
        params.add("unionId", unionId);
        params.add("userId", userId);
        HttpHeaders httpHeaders = new HttpHeaders();
        httpHeaders.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        HttpEntity<MultiValueMap<String, String>> requestEntity = new HttpEntity<>(params, httpHeaders);
        JSONObject stoResult = restTemplate.postForObject(userCenterUrl + BIND, requestEntity, JSONObject.class);