Now, we've finished the introduction to Spring Security. It's time to implement the login page of the user module. In this section, we will cover the frontend implementation and the backend implementation of the login page, as well as the unit tests of these two parts. However, since most of the implementation of the login page, including the frontend and the backend, is similar to the implementation of the register page, we will only focus on the part that only the login page has, which is to authenticate requests with Spring Security. You can always find the details that are not covered in this book on GitHub by using the commit record.
Let's implement the UI of the page. The following shows what he login page looks like:
Figure 10.13: The UI of the login page
As you can see, we support signing in by using either a username or email address. On the login page, there is a link to the register page, as well as another to the forgot password...