From aa122113ade36f02dc8fdbebdf1232b5c4b8742c Mon Sep 17 00:00:00 2001
From: Kamal Wickramanayake <kamal@inbox.lk>
Date: Fri, 3 Jul 2026 19:02:36 +0530
Subject: Microservice sample projects

---
 .../resourceserver/security/UserService.java       | 47 ++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 microservices/03-resource-server/src/main/java/com/example/resourceserver/security/UserService.java

(limited to 'microservices/03-resource-server/src/main/java/com/example/resourceserver/security/UserService.java')

diff --git a/microservices/03-resource-server/src/main/java/com/example/resourceserver/security/UserService.java b/microservices/03-resource-server/src/main/java/com/example/resourceserver/security/UserService.java
new file mode 100644
index 0000000..1f6ddac
--- /dev/null
+++ b/microservices/03-resource-server/src/main/java/com/example/resourceserver/security/UserService.java
@@ -0,0 +1,47 @@
+package com.example.resourceserver.security;
+
+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 jakarta.transaction.Transactional;
+
+@Service
+public class UserService {
+
+    @Autowired
+    private UserRepository userRepository;
+
+    public Optional<User> findByUsername(String username) {
+        return userRepository.findByUsername(username);
+    }
+
+    public Optional<User> findById(Long id) {
+        return userRepository.findById(id);
+    }
+
+    public List<User> findAll() {
+        return userRepository.findAll(Sort.by(Sort.Direction.ASC, "username"));
+    }
+
+    @PreAuthorize("hasRole('ADMIN')")
+    @Transactional
+    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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