Cognito用户池:如何刷新访问令牌Android

Question

如何使用Cognito for Android刷新访问令牌?文档建议如下(https://docs.aws.amazon.com/cognito/latest/developerguide/using-amazon-cognito-user-identity-pools-android-sdk.html):

// Implement authentication handler 
AuthenticationHandler handler = new AuthenticationHandler {
    @Override
    public void onSuccess(CognitoUserSession userSession) {
        // Authentication was successful, the "userSession" will have the current valid tokens
        // Time to do awesome stuff
    }
    @Override
    public void getAuthenticationDetails(final AuthenticationContinuation continuation, final String userID) {
        // User authentication details, userId and password are required to continue.
        // Use the "continuation" object to pass the user authentication details
        // After the user authentication details are available, wrap them in an AuthenticationDetails class
        // Along with userId and password, parameters for user pools for Lambda can be passed here
        // The validation parameters "validationParameters" are passed in as a Map<String, String>
        AuthenticationDetails authDetails = new AuthenticationDetails(userId, password, validationParameters);
        // Now allow the authentication to continue
        continuation.setAuthenticationDetails(authDetails);
        continuation.continueTask();
    }
    @Override
    public void getMFACode(final MultiFactorAuthenticationContinuation continuation) {
        // Multi-factor authentication is required to authenticate
        // A code was sent to the user, use the code to continue with the authentication

        // Find where the code was sent to
        String codeSentHere = continuation.getParameter()[0];
        // When the verification code is available, continue to authenticate
        continuation.setMfaCode(code);
        continuation.continueTask();
    }
    @Override
    public void authenticationChallenge(final ChallengeContinuation continuation) {
        // A custom challenge has to be solved to authenticate
        // Set the challenge responses
        // Call continueTask() method to respond to the challenge and continue with authentication.
    }
    @Override
    public void onFailure(final Exception exception) {
        // Authentication failed, probe exception for the cause
    }
};
user.getSession(handler);

这里是为什么这不起作用。当令牌过期时，我正在获取会话的用户对象不再经过身份验证。因此，通过以下方式检索缓存的用户，将返回null

CognitoUser user = userPool.getCurrentUser();

因为上面返回null，我尝试通过id

获取用户对象

CognitoUser user = userPool.getUser(userId);

它工作得很好，只是用户没有经过身份验证，并且在接下来的回调阶段会失败，因为userID为空

@Override
public void getAuthenticationDetails(final AuthenticationContinuation continuation, final String userID) 

只有当我在令牌过期之前尝试此调用时才会执行此操作，并且我可以接收新的访问令牌。但是，在令牌过期后，如何做到这一点呢?对此任何帮助都将不胜感激。提前感谢

Answer 1

当您调用getSession(…)-获取令牌-并且如果缓存的令牌已经过期，SDK将自动刷新令牌(只要刷新令牌没有过期)。如果刷新令牌也已过期，则调用getAuthenticationDetails(…)，因为现在需要用户凭据(用户名、密码等)来获取一组新的令牌。无论你如何获得用户对象，即通过getCurrentUser()或getUser(…)方法，只要有有效的缓存令牌或如果令牌可以刷新，你将获得有效的令牌与getSession(…)。

使用最新SDK (ver 2.3.1)重试