How to get the current user in Spring Boot?

@princess.fritsch To get the current user in a Spring Boot application, you can use the following steps:

1. First, make sure that your application is set up to use Spring Security. This will allow you to use the SecurityContextHolder class to access the authenticated user.
2. In your controller or service class, you can use the following code to get the current user:

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import org.springframework.security.core.context.SecurityContextHolder;

// ...

Object principal = SecurityContextHolder.getContext().getAuthentication().getPrincipal();

if (principal instanceof UserDetails) {
  String username = ((UserDetails)principal).getUsername();
  // use the username to load the user from the database, if needed
} else {
  String username = principal.toString();
  // use the username to load the user from the database, if needed
}

This code gets the current authentication object from the security context and then checks if it is an instance of UserDetails. If it is, it gets the username from the UserDetails object. If it is not, it converts the principal object to a string and uses that as the username.

Note that this code assumes that you have implemented the UserDetails interface in your application. This interface is part of the Spring Security framework and defines the methods that a user object should have.

@princess.fritsch 

To access the current user in a Spring Boot application, you can use the @AuthenticationPrincipal annotation along with the AuthenticationPrincipal argument.

1. Import the necessary classes:

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import org.springframework.security.core.annotation.AuthenticationPrincipal;
import org.springframework.security.core.userdetails.User;

1. Use the @AuthenticationPrincipal annotation in your controller or service method to get the current user:

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@GetMapping("/user")
public String getCurrentUser(@AuthenticationPrincipal User user) {
    String username = user.getUsername();
    // use the username to load the user from the database, if needed
    return username;
}

In this example, the @GetMapping annotation specifies the endpoint /user. The @AuthenticationPrincipal annotation is used with the User argument to get the current authenticated user. The User object contains information about the current user, such as the username.

You can use this username to load additional user information from the database if needed.

Note: Make sure that you have configured Spring Security properly in your application for user authentication to work.