In this chapter, you learned how to use Spring Security with confidence. First, we covered what Spring Security is as well as its architecture. We also learned about the advantage of using Spring Security, looking at its features and modules. Now, we're able to implement Spring Security in any project. We learned what the basic authentication is and, using an example, we saw how to implement the basic authentication in a project as well as how to secure the resources in a server. We also learned how to create a secured REST API. Then we learned how to create a client application in Android to fetch and use the protected resources from the REST API. We also learned how to implement a username and password to get access to the basic authentication-based secured server. In addition, we familiarized ourselves with how to use a custom adapter in a listview in the client application. In the last section, we explored a better-secured protocol: OAuth2. We learned the role and workflow of this protocol. With a simple project, we learned how to configure the OAuth2 authorization and resource servers. Finally, we saw how to retrieve the REST API using a third-party HTTP client.

In the next chapter, we'll learn about the database, which is very important, as it's the main place to store and handle your data.