获取 JWT 令牌 - 获取 401 未经授权但从邮递员工作

如何解决获取 JWT 令牌 - 获取 401 未经授权但从邮递员工作

有人可以帮助理解下面的代码是否有任何问题，或者可以做些什么来解决相同的问题？这些服务从 POSTMAN 工作，但通过代码出错

出现错误：

Exception and getting token :org.springframework.web.client.HttpClientErrorException: 401 Unauthorized

以下是服务代码，尝试使用 URL 编码以及 ClientId 和客户端机密编码到 base64，但没有奏效。

public class TestAPServices {
    public static String ChequeIssueCheckEndPointURL = "https://Cheque.com/accounting/api/Cheque";
    public static String ChequeUserID = "";
    public static String ChequeUserPassword = "";
    public static String ChequeIsAuthRequired = "Y";
    public static String ChequeSecurityType = "OAUTH2";
    public static String ChequeAccessTokenURI = "https://Cheque.com/oauth/token";
    public static String ChequeGrantType = "client_credentials";
    public static String ChequeClientId = "4YPC5FFFFFx0vsECzTft7Vyc6dVLdLJT";
    public static String ChequeClientSecret = "gHBp7YYYaAA7HGWn";
        
    private static void apChequeIssueCheck() throws Exception {

        String url = ChequeIssueCheckEndPointURL;
        String token = null;        
        RestTemplate restTemplate = new RestTemplate();
        HttpHeaders headers = new HttpHeaders();

        if ("Y".equals(ChequeIsAuthRequired) && "OAUTH2".equals(ChequeSecurityType))
            token = getOauthToken();
        //....
        //service call
    }


    public static String getOauthToken() throws Exception {
        try {
            String url = ChequeAccessTokenURI;

            RestTemplate restTemplate = new RestTemplate();
            HttpHeaders headers = new HttpHeaders();
            
            HttpEntity entity = new HttpEntity(headers);
            HttpEntity<String> response = null;
            ResponseEntity responseEntity = null;

            System.out.println("URL : " + url + "\t GrantType : " + ChequeGrantType + "\t client_id : "
                    + ChequeClientId + "\t Client Secret :" + ChequeClientSecret);
            
            url = (UriComponentsBuilder.fromHttpUrl(url)).build().encode().toUri() + "?" + Constants.GRANT_TYPE + "=" + ChequeGrantType + "&" + Constants.CLIENT_ID + "="+ Base64.byteArrayToBase64(ChequeClientId.getBytes("UTF-8")) 
            + "&" + Constants.CLIENT_SECRET + "=" + Base64.byteArrayToBase64(ChequeClientSecret.getBytes("UTF-8"));
            System.out.println("URL : "+ url);

            response = restTemplate.exchange(url,HttpMethod.POST,entity,String.class);
            // failed here
            //... futher code to read token
            return  (String) ((JSONObject) parser.parse(response.getBody())).get("access_token");
        }
    }
}