From f0001c5c8d8a33729b93d8d6e10d3af40bfabed6 Mon Sep 17 00:00:00 2001
From: Kamal Wickramanayake <kamal@inbox.lk>
Date: Sat, 13 Jun 2026 21:03:31 +0530
Subject: Added sample application 09-spring-security-db-authentication

---
 .../java/com/example/spring/user/entity/User.java  | 53 ++++++++++++++++++++++
 .../spring/user/repository/UserRepository.java     | 13 ++++++
 .../user/service/CustomUserDetailsService.java     | 25 ++++++++++
 3 files changed, 91 insertions(+)
 create mode 100644 spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/entity/User.java
 create mode 100644 spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/repository/UserRepository.java
 create mode 100644 spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/service/CustomUserDetailsService.java

(limited to 'spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user')

diff --git a/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/entity/User.java b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/entity/User.java
new file mode 100644
index 0000000..a8ec6d2
--- /dev/null
+++ b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/entity/User.java
@@ -0,0 +1,53 @@
+package com.example.spring.user.entity;
+
+import java.util.ArrayList;
+import java.util.Collection;
+
+import org.springframework.security.core.GrantedAuthority;
+import org.springframework.security.core.userdetails.UserDetails;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import jakarta.persistence.Table;
+
+/*
+    @Table - Used to set the database table name explicitely.
+*/
+@Entity
+@Table(name="user_account")
+public class User implements UserDetails {
+
+    /*
+        GenerationType.IDENTITY - Auto generate value based on database's native auto increment feature 
+    */
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    @Column(unique = true)
+    private String username;
+
+    private String password;
+
+    /*
+        Roles and permissions can be represented by GrantedAuthority instances.
+    */
+    @Override
+    public Collection<? extends GrantedAuthority> getAuthorities() {
+        return new ArrayList<>();
+    }
+
+    @Override
+    public String getPassword() {
+        return password;
+    }
+
+    @Override
+    public String getUsername() {
+        return username;
+    }
+
+}
diff --git a/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/repository/UserRepository.java b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/repository/UserRepository.java
new file mode 100644
index 0000000..f719637
--- /dev/null
+++ b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/repository/UserRepository.java
@@ -0,0 +1,13 @@
+package com.example.spring.user.repository;
+
+import java.util.Optional;
+
+import org.springframework.data.repository.ListCrudRepository;
+import org.springframework.stereotype.Repository;
+
+import com.example.spring.user.entity.User;
+
+@Repository
+public interface UserRepository extends ListCrudRepository<User, Long> {
+    Optional<User> findByUsername(String username);
+}
diff --git a/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/service/CustomUserDetailsService.java b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/service/CustomUserDetailsService.java
new file mode 100644
index 0000000..c61649e
--- /dev/null
+++ b/spring-boot/09-spring-security-db-authentication/src/main/java/com/example/spring/user/service/CustomUserDetailsService.java
@@ -0,0 +1,25 @@
+package com.example.spring.user.service;
+
+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 com.example.spring.user.repository.UserRepository;
+
+@Service
+public class CustomUserDetailsService implements UserDetailsService {
+
+    private final UserRepository userRepository;
+
+    public CustomUserDetailsService(UserRepository userRepository) {
+        this.userRepository = userRepository;
+    }
+
+    @Override
+    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
+        return userRepository.findByUsername(username)
+                .orElseThrow(() -> new UsernameNotFoundException("User not found"));
+    }
+
+}
\ No newline at end of file
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