JwtUserDetailsService.java

package com.example.api.service;

import com.example.api.repository.UserRepository;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

import java.util.ArrayList;
import java.util.List;

@Service
public class JwtUserDetailsService implements UserDetailsService {

    final UserRepository userRepository;

    public JwtUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        com.example.api.model.User user = userRepository.findUserByUsername(username);
        List<GrantedAuthority> authorityList = new ArrayList<>();
        authorityList.add(new SimpleGrantedAuthority("USER_ROLE"));
        return new User(user.getUserName(), user.getPassword(), authorityList);
    }
}