The new Certification Class of Learn Spring Security is out:


1. Overview

In this tutorial, we’ll use Spring Security OAuth to authenticate with the Reddit API.

2. Maven Configuration

First, in order to use Spring Security OAuth – we need to add the following dependency to our pom.xml (of course along any other Spring dependency you might use):


3. Configure OAuth2 Client

Next – let’s configure our OAuth2 client – the OAuth2RestTemplate – and a file for all the authentication related properties:

protected static class ResourceConfiguration {

    private String accessTokenUri;

    private String userAuthorizationUri;

    private String clientID;

    private String clientSecret;

    public OAuth2ProtectedResourceDetails reddit() {
        AuthorizationCodeResourceDetails details = new AuthorizationCodeResourceDetails();
        return details;

    public OAuth2RestTemplate redditRestTemplate(OAuth2ClientContext clientContext) {
        OAuth2RestTemplate template = new OAuth2RestTemplate(reddit(), clientContext);
        AccessTokenProvider accessTokenProvider = new AccessTokenProviderChain(
          Arrays.<AccessTokenProvider> asList(
            new MyAuthorizationCodeAccessTokenProvider(), 
            new ImplicitAccessTokenProvider(), 
            new ResourceOwnerPasswordAccessTokenProvider(),
            new ClientCredentialsAccessTokenProvider())
        return template;


And ““:


You can get your own secret code by creating a Reddit app from

We’re going to use the OAuth2RestTemplate to:

  1. Acquire the access token needed to access the remote resource.
  2. Access the remote resource after getting the access token.

Also note how we added the scope “identity” to Reddit OAuth2ProtectedResourceDetails so that we can retrieve the users account information later.

4. Custom AuthorizationCodeAccessTokenProvider

The Reddit OAuth2 implementation is a little different from the standard. And so – instead of elegantly extending the AuthorizationCodeAccessTokenProvider – we need to actually override some portions of it.

There are github issues tracking improvements that will make this not necessary, but these issues are not yet done.

One of the non-standard things that Reddit does is – when we redirect the user and prompt him to authenticate with Reddit, we need to have some custom parameters in the redirect URL. More specifically – if we’re asking for a permanent access token from Reddit – we need to add a parameter “duration” with the value “permanent“.

So, after extending AuthorizationCodeAccessTokenProvider – we have added this parameter in the getRedirectForAuthorization() method:

    requestParameters.put("duration", "permanent");

You can check the full source code from here.

5. The ServerInitializer

Next – let’s create our custom ServerInitializer.

We need to add a filter bean with id oauth2ClientContextFilter, so that we can use it to store the current context:

public class ServletInitializer extends AbstractDispatcherServletInitializer {

    protected WebApplicationContext createServletApplicationContext() {
        AnnotationConfigWebApplicationContext context = 
          new AnnotationConfigWebApplicationContext();
        context.register(WebConfig.class, SecurityConfig.class);
        return context;

    protected String[] getServletMappings() {
        return new String[] { "/" };

    protected WebApplicationContext createRootApplicationContext() {
        return null;

    public void onStartup(ServletContext servletContext) throws ServletException {
        registerProxyFilter(servletContext, "oauth2ClientContextFilter");
        registerProxyFilter(servletContext, "springSecurityFilterChain");

    private void registerProxyFilter(ServletContext servletContext, String name) {
        DelegatingFilterProxy filter = new DelegatingFilterProxy(name);
        servletContext.addFilter(name, filter).addMappingForUrlPatterns(null, false, "/*");

6. MVC Configuration

Now – let’s take a look at our MVC configuration of our simple web-app:

@ComponentScan(basePackages = { "org.baeldung.web" })
public class WebConfig extends WebMvcConfigurerAdapter {

    public static PropertySourcesPlaceholderConfigurer 
      propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();

    public ViewResolver viewResolver() {
        InternalResourceViewResolver viewResolver = new InternalResourceViewResolver();
        return viewResolver;

    public void configureDefaultServletHandling(
      DefaultServletHandlerConfigurer configurer) {

    public void addResourceHandlers(ResourceHandlerRegistry registry) {

    public void addViewControllers(ViewControllerRegistry registry) {

7. Security Configuration

Next – let’s take a look at the main Spring Security configuration:

public class SecurityConfig extends WebSecurityConfigurerAdapter {

    protected void configure(AuthenticationManagerBuilder auth) 
      throws Exception {

    protected void configure(HttpSecurity http) throws Exception {

    private LoginUrlAuthenticationEntryPoint oauth2AuthenticationEntryPoint() {
        return new LoginUrlAuthenticationEntryPoint("/login");

Note: We added a simple security configuration that redirect to “/login” which get the user information and load authentication from it – as explained in the following section.

8. RedditController

Now – let’s take a look at our controller RedditController.

We use method redditLogin() to get the user information from his Reddit account and load an authentication from it – as in the following example:

public class RedditController {

    private OAuth2RestTemplate redditRestTemplate;

    public String redditLogin() {
        JsonNode node = redditRestTemplate.getForObject(
          "", JsonNode.class);
        UsernamePasswordAuthenticationToken auth = 
          new UsernamePasswordAuthenticationToken(node.get("name").asText(), 
          Arrays.asList(new SimpleGrantedAuthority("ROLE_USER")));
        return "redirect:home.html";


An interesting detail of this deceptively simple method – the reddit template checks if the access token is available before executing any request; it acquires a token if one is not available.

Next – we present the information to our very simplistic front end.

9. home.jsp

Finally – let’s take a look at home.jsp – to display the information retrieved form user’s Reddit account:

<%@ taglib prefix="c" uri=""%>
<%@ taglib prefix="sec" uri=""%>
    <h1>Welcome, <small><sec:authentication property="principal.username" /></small></h1>

10. Conclusion

In this introductory article, we explored authenticating with the Reddit OAuth2 API and displaying some very basic information in a simple front end.

Now that we’re authenticated, we’re going to explore doing more interesting things with the Reddit API in the next article of this new series.

The full implementation of this tutorial can be found in the github project – this is an Eclipse based project, so it should be easy to import and run as it is.

Go deeper into Spring Security with the course:


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Could you please provide the complete source code? It will be great help for all your followers, if you’d allow us to do that.

Eugen Paraschiv

Not sure what you mean – there’s a link at the end of the article to the full source code over on github 🙂

cristian borta

The link provided is broken, Eugen. Could you please fix this issue? Thanks

Eugen Paraschiv

Fixed – thanks for letting me know. Cheers,


I have this exception “ Authentication is required to obtain an access token (anonymous not allowed)” when i try to login. Can you tell me how to fix this exception?

Eugen Paraschiv

So – not sure how you ran into that – is there maybe a quick test that we can use to replicate it? Or some scenario? If it simply happens on login – what’s the full stack there?

Guest Authentication is required to obtain an access token (anonymous not allowed)
at org.springframework.web.client.RestTemplate.doExecute(
at org.springframework.web.client.RestTemplate.execute(
at org.springframework.web.client.RestTemplate.getForObject(
at com.hopeless.web.controller.LoginController.login(

Is it have to authentication in localhost before authentication in reddit?

Eugen Paraschiv

I’ve tried to replicate the issue without luck. If you can get a reproducible sequence of steps that’s going to help flush this out, I’d be happy to try again.
Also – let’s move this to an issue over on Github – it’s going to be easier than having a technical discussion here. Cheers,

Hi Eugen, very nice tutorial. I have a questions, I want to create mobile app (in this time android) and spring boot rest server site. For authentication in first time I used classic user password spring security way but with rest not MVC (post username and password in to the default spring security login page url from my mobile app) it worked but its is not a ideal because a had a problem with session time out on mobile device. My second way I used spring oauth grand type user and password it works very good i have a refresh… Read more »
Eugen Paraschiv
Hey MoVa, That’s a relatively standard scenario you have, where you just want to use an Android app as a client. Two quick things here. First – I haven’t worked with the Facebook API, so I can’t be to specific, but if you have a refresh token, you’ll of course be able to use that to refresh your access token when it expires – hence you’ll be able to work around your session expiration problems. Now – on to the communication side of things, once you have your access token, you’ll simply be able to hit the API and consume… Read more »
Joseph Stoll

This article is amazing. I’ve had a lot of trouble finding something this clear while working on my current Spring Security problem.

Question: In the bean redditRestTemplate(OAuth2ClientContext clientContext), how does Spring know where to get the Oauth2ClientContext from? I checked your full source code in Github, and I don’t see it configured anywhere. It feels as though it appears by magic.

I’m having some troubles initializing this bean and wanted to see if there was anything I was missing.

Eugen Paraschiv

Glad you like the article Joseph – it’s the start of a pretty long series that all started with this one. So, like many other beans, the OAuth client context is defined by the framework itself. Not sure if it’s coming out of Boot, but you should be able to easily trace back the creation of the bean by simply debugging through the context bootstrapping process and seeing where it gets created.
Hope that helps. Cheers,


How such a small project has turned into a huge?

Eugen Paraschiv

Hey Alex – that’s a good question.
The answer is – it started as a POC and evolved into a system I am actually using, which means it has to be production-grade, not just an example. That’s why the project grow.
Of course, ultimately – it’s still a very small project with only a couple of features.
Hope that answers your question. Cheers,