android - Cognito 用户池 : How to refresh Access Token Android

Question

如何使用 Cognito for Android 刷新访问 token ？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);

这就是为什么这不起作用。当 token 过期时，我为其获取 session 的用户对象不再经过身份验证。所以通过下面检索缓存的用户，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);

这完美地工作，除了用户未通过身份验证并且将在随后的回调阶段失败，因为 userID 为空

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

只有当我在 token 过期之前尝试此调用时，它才会起作用，并且我可以收到一个新的访问 token 。但是 token 过期后怎么办呢？对此的任何帮助将不胜感激。提前致谢

Answer 1

当您调用 getSession(...) 获取 token 时，如果缓存的 token 已过期，SDK 将自动刷新 token (只要刷新 token 未过期)。如果刷新 token 也已过期，则会调用 getAuthenticationDetails(...)，因为现在需要用户凭据(用户名、密码等)才能获取新的 token 集。获取用户对象的方式无关紧要，即通过 getCurrentUser() 或 getUser(...) 方法，只要存在有效的缓存 token 或 token 可以刷新，您将通过 getSession(. ..).

使用最新的 SDK(版本 2.3.1)重试。