将OAuth2RestTemplate公开为AsyncRestTemplate

Question

I have a working OAuth2RestTemplate client (I'm using spring-security-oauth2 2.0.7.RELEASE). Now I'd like to expose/wrap it as AsyncRestTemplate to take advantage of asynchronous semantic of ListenableFuture. Unfortunately the following straightforward approach doesn't work:

// instantiate and configure OAuth2RestTemplate - works
OAuth2RestTemplate oAuth2RestTemplate = new OAuth2RestTemplate(...);

// wrap sync restTemplate with AsyncRestTemplate - doesn't work 
AsyncRestTemplate asyncRestTemplate = new AsyncRestTemplate(
    new HttpComponentsAsyncClientHttpRequestFactory(), oAuth2RestTemplate);

How can I get OAuth2 Rest client for my HTTP service as AsyncRestTemplate?

Answer 1

Ok, I was able to make AsyncRestTemplate work by manually setting "Authorization" header with accessToken from OAuth2RestTemplate; here's Spring java configuration for that:

@Bean
public OAuth2RestTemplate restTemplate() {
    ClientCredentialsResourceDetails details = new ClientCredentialsResourceDetails();
    // configure oauth details

    OAuth2RestTemplate restTemplate = new OAuth2RestTemplate(details);
    restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());

    return restTemplate;
}

@Bean
public AsyncRestTemplate asyncRestTemplate(final OAuth2RestTemplate oAuth2RestTemplate) {
    HttpComponentsAsyncClientHttpRequestFactory asyncRequestFactory = new HttpComponentsAsyncClientHttpRequestFactory() {
        @Override
        public AsyncClientHttpRequest createAsyncRequest(URI uri, HttpMethod httpMethod) throws IOException {
            AsyncClientHttpRequest asyncRequest = super.createAsyncRequest(uri, httpMethod);

            OAuth2AccessToken accessToken = oAuth2RestTemplate.getAccessToken();
            asyncRequest.getHeaders().set("Authorization", String.format("%s %s", accessToken.getTokenType(), accessToken.getValue()));

            return asyncRequest;
        }
    };
    return new AsyncRestTemplate(asyncRequestFactory, oAuth2RestTemplate);
}

I wish there would be easier way to expose configured OAuth2RestTemplate as AsyncRestTemplate in Spring.

Answer 2

The above works, but I've found a much neater way of doing it. Register an implementation AsyncClientHttpRequestInterceptor

Example code:

private class Oauth2RequestInterceptor implements AsyncClientHttpRequestInterceptor
{
    private final OAuth2RestTemplate oAuth2RestTemplate;

    public Oauth2RequestInterceptor( OAuth2RestTemplate oAuth2RestTemplate )
    {
        this.oAuth2RestTemplate = oAuth2RestTemplate;
    }

    public ListenableFuture<ClientHttpResponse> intercept( HttpRequest request, byte[] body,
        AsyncClientHttpRequestExecution execution ) throws IOException
    {
        OAuth2AccessToken accessToken = oAuth2RestTemplate.getAccessToken();
        request.getHeaders()
            .set( "Authorization", String.format( "%s %s", accessToken.getTokenType(), accessToken.getValue() ) );
        return execution.executeAsync( request, body );
    }
}

Then register it with your AsyncRestTemplate :

@Bean
public AsyncRestTemplate asyncRestTemplate( AsyncClientHttpRequestFactory factory, OAuth2RestTemplate restTemplate )
{
    AsyncRestTemplate asyncRestTemplate = new AsyncRestTemplate( factory, restTemplate );
    asyncRestTemplate.setInterceptors( Collections.singletonList( new Oauth2RequestInterceptor( restTemplate ) ) );
    return asyncRestTemplate;
}