From 69b18c1fe1d7d876c86de850b716de396877ad9d Mon Sep 17 00:00:00 2001
From: Kamal Wickramanayake <kamal@inbox.lk>
Date: Sat, 20 Jun 2026 22:02:32 +0530
Subject: A list of users are shown. Added error pages.

---
 .../security/service/CustomUserDetailsService.java |  1 -
 .../spring/security/service/UserService.java       | 12 ++++++
 .../spring/security/service/UserServiceImpl.java   | 49 ++++++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserService.java
 create mode 100644 spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserServiceImpl.java

(limited to 'spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service')

diff --git a/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/CustomUserDetailsService.java b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/CustomUserDetailsService.java
index cdced4a..1795109 100644
--- a/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/CustomUserDetailsService.java
+++ b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/CustomUserDetailsService.java
@@ -21,5 +21,4 @@ public class CustomUserDetailsService implements UserDetailsService {
         return userRepository.findByUsername(username)
                 .orElseThrow(() -> new UsernameNotFoundException("User not found"));
     }
-
 }
\ No newline at end of file
diff --git a/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserService.java b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserService.java
new file mode 100644
index 0000000..a4e18be
--- /dev/null
+++ b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserService.java
@@ -0,0 +1,12 @@
+package com.example.spring.security.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import com.example.spring.security.entity.User;
+
+public interface UserService {
+    public Optional<User> findById(Long id);
+    public List<User> findAll();
+    public void updateUser(Long userId, String description);
+}
diff --git a/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserServiceImpl.java b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserServiceImpl.java
new file mode 100644
index 0000000..0d44d21
--- /dev/null
+++ b/spring-boot/10-role-based-security/src/main/java/com/example/spring/security/service/UserServiceImpl.java
@@ -0,0 +1,49 @@
+package com.example.spring.security.service;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Sort;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.stereotype.Service;
+
+import com.example.spring.security.entity.User;
+import com.example.spring.security.repository.UserRepository;
+
+import jakarta.transaction.Transactional;
+
+@Service
+public class UserServiceImpl implements UserService {
+
+    @Autowired
+    private UserRepository userRepository;
+
+        @Override
+    public Optional<User> findById(Long id) {
+        return userRepository.findById(id);
+    }
+
+    @Override
+    public List<User> findAll() {
+        return userRepository.findAll(Sort.by(Sort.Direction.ASC, "username"));
+    }
+
+    @PreAuthorize("hasRole('ADMIN')")
+    @Transactional
+    @Override
+    public void updateUser(Long id, String description) {
+        // Do whatever the work needed.
+        // ...
+
+        Optional<User> userOpt = userRepository.findById(id);
+
+        User user = userOpt.get();
+
+        user.setDescription(description);
+
+        // NO userRepository.save(user) IS ACTUALLY REQUIRED HERE since the method
+        // has been annotated with @Transactional!
+        // Transaction commits -> Hibernate issues the SQL UPDATE.
+    }
+}
-- 
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