Implementing UserDetailsServiceImpl and creating UserRepository

src/main/java/com/ecommerce/sb_ecom/repository/UserRepository.java

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+package com.ecommerce.sb_ecom.repository;
+
+import com.ecommerce.sb_ecom.model.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.Optional;
+
+public interface UserRepository extends JpaRepository<User, Long> {
+
+    Optional<User> findByUsername(String username);
+}

src/main/java/com/ecommerce/sb_ecom/security/services/UserDetailsServiceImpl.java

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+package com.ecommerce.sb_ecom.security.services;
+
+import com.ecommerce.sb_ecom.model.User;
+import com.ecommerce.sb_ecom.repository.UserRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+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 org.springframework.transaction.annotation.Transactional;
+
+@Service
+public class UserDetailsServiceImpl implements UserDetailsService {
+
+    @Autowired
+    UserRepository userRepository;
+
+    @Override
+    @Transactional
+    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
+        User user = userRepository.findByUsername(username)
+                .orElseThrow(()->new UsernameNotFoundException("User Not Found With Username : "+ username));
+        return UserDetailsImpl.build(user);
+    }
+}