当Android Retrofit收到UnAuthenticated响应（也称为401错误）时，可以通过以下代码示例来处理：

首先，定义一个错误处理类，例如UserAuthError.java：

public class UserAuthError extends Throwable {
    public UserAuthError(String message) {
        super(message);
    }
}

然后，在Retrofit API接口中，添加对UnAuthenticated响应的处理，例如UserService.java：

public interface UserService {
    @GET("/user/dashboard")
    Call getUserDashboard();

    // Add this method to handle UnAuthenticated response (401)
    @GET("/user/token")
    Call refreshToken();
}

接下来，在Retrofit API的实现类中，处理401响应并尝试刷新令牌（Token），例如UserServiceImpl.java：

public class UserServiceImpl implements UserService {
    private UserService userService;
    private String token;

    public UserServiceImpl() {
        // Initialize Retrofit instance with token interceptor
        OkHttpClient.Builder httpClient = new OkHttpClient.Builder()
                .addInterceptor(new Interceptor() {
                    @Override
                    public Response intercept(Chain chain) throws IOException {
                        Request original = chain.request();
                        Request.Builder requestBuilder = original.newBuilder()
                                .header("Authorization", "Bearer " + token)
                                .method(original.method(), original.body());
                        Request request = requestBuilder.build();
                        Response response = chain.proceed(request);
                        if (response.code() == 401) {
                            // Refresh token and retry request
                            token = refreshToken();
                            request = request.newBuilder()
                                    .header("Authorization", "Bearer " + token)
                                    .build();
                            response = chain.proceed(request);
                        }
                        return response;
                    }
                });
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://api.example.com/")
                .addConverterFactory(GsonConverterFactory.create())
                .client(httpClient.build())
                .build();
        userService = retrofit.create(UserService.class);
    }

    @Override
    public Call getUserDashboard() {
        return userService.getUserDashboard();
    }

    @Override
    public Call refreshToken() {
        // Send POST request to refresh token API
        // and return new token in response body