Spring Boot RestTemplate发送带urlencode体的GET请求失败排查

我需要用认证令牌发送通知，获取令牌的curl命令能正常运行，但用Spring Boot的RestTemplate写的等效代码报错unsupported_grant_type，请求帮忙排查问题。

CURL命令 #

curl --location --request GET 'https://test.appleexpress.com/orderservicesapi/token' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--header 'Cookie: visid_incap_2670687=PgVnXOJwTveM+f+unLbHivuZr2QAAAAAQUIPAAAAAAAGR2Wbz5NgMv8yRX/u7VZP' \
--data-urlencode 'username=3062:HONGKONGWISE' \
--data-urlencode 'password=mjtwj2v7YfsUstu' \
--data-urlencode 'grant_type=password'

RestTemplate实现代码 #

public void getToken() throws UnsupportedEncodingException {

        String username = "3062:HONGKONGWISE";
        String password = "mjtwj2v7YfsUstu";
        String grantType = "password";
        String params = "username=" + URLEncoder.encode(username, "UTF-8") +
                "&password=" + URLEncoder.encode(password, "UTF-8") +
                "&grant_type=" + URLEncoder.encode(grantType, "UTF-8");

        ResponseEntity<String> responseEntity = null;
        RestTemplate restTemplate = utils.getClientTimeOutInRestTemplate();
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        headers.set("Cookie", "visid_incap_2670687=PgVnXOJwTveM+f+unLbHivuZr2QAAAAAQUIPAAAAAAAGR2Wbz5NgMv8yRX/u7VZP");
        HttpEntity<String> entity = new HttpEntity<>(params,headers);


        try {
            log.info("RMS_SERVER : getToken : Authorization API : {}", authUrl);
            log.info("RMS_SERVER : getToken : Sendind Request to authorization API : {}", entity);

            responseEntity = restTemplate.exchange(authUrl, HttpMethod.GET, entity, String.class);

            if (responseEntity.getStatusCode().is2xxSuccessful() && null != responseEntity.getBody()) {
                log.info("RMS_SERVER : getToken : Response of authorization API is: {}", responseEntity.getBody());
                String authRequest = responseEntity.getBody();
                JSONObject jsonAuthRequest = new JSONObject(authRequest);
                this.setAuthtoken(jsonAuthRequest.getString(ACCESS_TOKEN));
                log.info("RMS_SERVER : getToken : Token successfully received ");
            } else {
                log.error("RMS_SERVER : getToken : Token not received ");
            }
        } catch (HttpStatusCodeException e) {
            log.error(String.format("RMS_SERVER : getToken : HttpStatusCodeException Occurred Caused By: %s : Status Code : %s ", e.getResponseBodyAsString(), e.getStatusCode()));
            throw new AppException(e.getResponseBodyAsString(), e.getStatusCode());
        } catch (ResourceAccessException e) {
            log.error(String.format("RMS_SERVER : getToken : ResourceAccessException Occurred Caused By: %s", e.getLocalizedMessage()));
            throw new AppException(e.getLocalizedMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        } catch (RestClientException e) {
            log.error("RMS_SERVER : getToken : Received exception while sending Request to authorization API: %s" + e.getLocalizedMessage());
            throw new AppException(e.getLocalizedMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

报错信息 #

2023-07-27T07:20:16.640Z  INFO  26520 --- [scheduling-1] com.gor.si.service.impl.AuthServiceImpl: RMS_SERVER : getToken : Authorization API : https://test.appleexpress.com/orderservicesapi/token
2023-07-27T07:20:16.640Z  INFO  26520 --- [scheduling-1] com.gor.si.service.impl.AuthServiceImpl: RMS_SERVER : getToken : Sendind Request to authorization API : <username=3062%3AHONGKONGWISE&password=mjtwj2v7YfsUstu&grant_type=password,[Content-Type:"application/x-www-form-urlencoded", Cookie:"visid_incap_2670687=PgVnXOJwTveM+f+unLbHivuZr2QAAAAAQUIPAAAAAAAGR2Wbz5NgMv8yRX/u7VZP"]>
2023-07-27T07:20:17.799Z  ERROR 26520 --- [scheduling-1] com.gor.si.service.impl.AuthServiceImpl: RMS_SERVER : getToken : HttpStatusCodeException Occurred Caused By: {"error":"unsupported_grant_type"} : Status Code : 400 BAD_REQUEST 
2023-07-27T07:20:17.803Z  ERROR 26520 --- [scheduling-1] org.springframework.scheduling.support.TaskUtils$LoggingErrorHandler: Unexpected error occurred in scheduled task
com.gor.si.exception.AppException: {"error":"unsupported_grant_type"}
    at com.gor.si.service.impl.AuthServiceImpl.getToken(AuthServiceImpl.java:80)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:84)
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

问题原因及修复方案 #

核心问题 #

GET请求携带请求体不符合HTTP标准，虽然curl可以强制发送，但RestTemplate的处理逻辑或后端服务的解析规则会忽略GET请求体，导致服务无法识别grant_type参数，返回unsupported_grant_type。

修复步骤 #

1. 改用POST请求：OAuth2密码模式的标准请求方式为POST，将HttpMethod.GET替换为HttpMethod.POST。
2. 用MultiValueMap传递表单参数：Spring会自动处理参数编码，避免手动编码可能出现的错误。

修改后的代码示例：

public void getToken() {
        String username = "3062:HONGKONGWISE";
        String password = "mjtwj2v7YfsUstu";
        String grantType = "password";

        // 构建表单参数
        MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
        params.add("username", username);
        params.add("password", password);
        params.add("grant_type", grantType);

        ResponseEntity<String> responseEntity = null;
        RestTemplate restTemplate = utils.getClientTimeOutInRestTemplate();
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);
        headers.set("Cookie", "visid_incap_2670687=PgVnXOJwTveM+f+unLbHivuZr2QAAAAAQUIPAAAAAAAGR2Wbz5NgMv8yRX/u7VZP");
        HttpEntity<MultiValueMap<String, String>> entity = new HttpEntity<>(params, headers);

        try {
            log.info("RMS_SERVER : getToken : Authorization API : {}", authUrl);
            log.info("RMS_SERVER : getToken : Sending Request to authorization API : {}", entity);

            // 改为POST请求
            responseEntity = restTemplate.exchange(authUrl, HttpMethod.POST, entity, String.class);

            if (responseEntity.getStatusCode().is2xxSuccessful() && null != responseEntity.getBody()) {
                log.info("RMS_SERVER : getToken : Response of authorization API is: {}", responseEntity.getBody());
                String authRequest = responseEntity.getBody();
                JSONObject jsonAuthRequest = new JSONObject(authRequest);
                this.setAuthtoken(jsonAuthRequest.getString(ACCESS_TOKEN));
                log.info("RMS_SERVER : getToken : Token successfully received ");
            } else {
                log.error("RMS_SERVER : getToken : Token not received ");
            }
        } catch (HttpStatusCodeException e) {
            log.error(String.format("RMS_SERVER : getToken : HttpStatusCodeException Occurred Caused By: %s : Status Code : %s ", e.getResponseBodyAsString(), e.getStatusCode()));
            throw new AppException(e.getResponseBodyAsString(), e.getStatusCode());
        } catch (ResourceAccessException e) {
            log.error(String.format("RMS_SERVER : getToken : ResourceAccessException Occurred Caused By: %s", e.getLocalizedMessage()));
            throw new AppException(e.getLocalizedMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        } catch (RestClientException e) {
            log.error("RMS_SERVER : getToken : Received exception while sending Request to authorization API: {}", e.getLocalizedMessage());
            throw new AppException(e.getLocalizedMessage(), HttpStatus.INTERNAL_SERVER_ERROR);
        }
    }

特殊场景兼容（不推荐） #

如果后端强制要求用GET请求，可将参数拼接在URL查询字符串中（存在密码泄露风险）：

String url = authUrl + "?username=" + URLEncoder.encode(username, "UTF-8") + 
             "&password=" + URLEncoder.encode(password, "UTF-8") + 
             "&grant_type=" + URLEncoder.encode(grantType, "UTF-8");
responseEntity = restTemplate.exchange(url, HttpMethod.GET, new HttpEntity<>(headers), String.class);

内容的提问来源于stack exchange，提问作者amar