Upgrade to Java 21 and Spring Boot 3.4.1 LTS

pom.xml

@@ -8,7 +8,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.7.18</version>
+        <version>3.4.1</version>
         <relativePath/>
     </parent>
 
@@ -21,9 +21,9 @@
     <description>A simple photo storage and gallery application built with Spring Boot and Oracle DB</description>
 
     <properties>
-        <java.version>1.8</java.version>
-        <maven.compiler.source>8</maven.compiler.source>
-        <maven.compiler.target>8</maven.compiler.target>
+        <java.version>21</java.version>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
@@ -63,7 +63,7 @@
         <dependency>
             <groupId>commons-io</groupId>
             <artifactId>commons-io</artifactId>
-            <version>2.11.0</version>
+            <version>2.18.0</version>
         </dependency>
 
         <!-- Image processing -->

src/main/java/com/photoalbum/controller/DetailController.java

@@ -37,7 +37,7 @@ public String detail(@PathVariable String id, Model model) {
 
         try {
             Optional<Photo> photoOpt = photoService.getPhotoById(id);
-            if (!photoOpt.isPresent()) {
+            if (photoOpt.isEmpty()) {
                 return "redirect:/";
             }
 

src/main/java/com/photoalbum/controller/HomeController.java

@@ -54,7 +54,7 @@ public String index(Model model) {
      */
     @PostMapping("/upload")
     @ResponseBody
-    public ResponseEntity<Map<String, Object>> uploadPhotos(@RequestParam("files") List<MultipartFile> files) {
+    public ResponseEntity<Map<String, Object>> uploadPhotos(@RequestParam List<MultipartFile> files) {
         Map<String, Object> response = new HashMap<String, Object>();
         List<Map<String, Object>> uploadedPhotos = new ArrayList<Map<String, Object>>();
         List<Map<String, Object>> failedUploads = new ArrayList<Map<String, Object>>();

src/main/java/com/photoalbum/controller/PhotoFileController.java

@@ -45,7 +45,7 @@ public ResponseEntity<Resource> servePhoto(@PathVariable String id) {
             logger.info("=== DEBUGGING: Serving photo request for ID {} ===", id);
             Optional<Photo> photoOpt = photoService.getPhotoById(id);
 
-            if (!photoOpt.isPresent()) {
+            if (photoOpt.isEmpty()) {
                 logger.warn("Photo with ID {} not found", id);
                 return ResponseEntity.notFound().build();
             }

src/main/java/com/photoalbum/model/Photo.java

@@ -1,10 +1,10 @@
 package com.photoalbum.model;
 
-import javax.persistence.*;
-import javax.validation.constraints.NotBlank;
-import javax.validation.constraints.NotNull;
-import javax.validation.constraints.Positive;
-import javax.validation.constraints.Size;
+import jakarta.persistence.*;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Positive;
+import jakarta.validation.constraints.Size;
 
 import java.time.LocalDateTime;
 import java.util.UUID;

src/main/java/com/photoalbum/service/impl/PhotoServiceImpl.java

@@ -91,7 +91,7 @@ public UploadResult uploadPhoto(MultipartFile file) {
             // Validate file size
             if (file.getSize() > maxFileSizeBytes) {
                 result.setSuccess(false);
-                result.setErrorMessage(String.format("File size exceeds %dMB limit.", maxFileSizeBytes / 1024 / 1024));
+                result.setErrorMessage("File size exceeds %dMB limit.".formatted(maxFileSizeBytes / 1024 / 1024));
                 logger.warn("Upload rejected: File size {} exceeds limit for {}", 
                     file.getSize(), file.getOriginalFilename());
                 return result;
@@ -178,7 +178,7 @@ public UploadResult uploadPhoto(MultipartFile file) {
     public boolean deletePhoto(String id) {
         try {
             Optional<Photo> photoOpt = photoRepository.findById(id);
-            if (!photoOpt.isPresent()) {
+            if (photoOpt.isEmpty()) {
                 logger.warn("Photo with ID {} not found for deletion", id);
                 return false;
             }
@@ -203,7 +203,7 @@ public boolean deletePhoto(String id) {
     @Transactional(readOnly = true)
     public Optional<Photo> getPreviousPhoto(Photo currentPhoto) {
         List<Photo> olderPhotos = photoRepository.findPhotosUploadedBefore(currentPhoto.getUploadedAt());
-        return olderPhotos.isEmpty() ? Optional.<Photo>empty() : Optional.of(olderPhotos.get(0));
+        return olderPhotos.isEmpty() ? Optional.<Photo>empty() : Optional.of(olderPhotos.getFirst());
     }
 
     /**
@@ -213,7 +213,7 @@ public Optional<Photo> getPreviousPhoto(Photo currentPhoto) {
     @Transactional(readOnly = true)
     public Optional<Photo> getNextPhoto(Photo currentPhoto) {
         List<Photo> newerPhotos = photoRepository.findPhotosUploadedAfter(currentPhoto.getUploadedAt());
-        return newerPhotos.isEmpty() ? Optional.<Photo>empty() : Optional.of(newerPhotos.get(0));
+        return newerPhotos.isEmpty() ? Optional.<Photo>empty() : Optional.of(newerPhotos.getFirst());
     }
 
     /**

src/test/resources/application-test.properties

@@ -1,5 +1,5 @@
 # Test configuration - use H2 in-memory database for testing
-spring.datasource.url=jdbc:h2:mem:testdb
+spring.datasource.url=jdbc:h2:mem:testdb;DATABASE_TO_LOWER=TRUE;CASE_INSENSITIVE_IDENTIFIERS=TRUE
 spring.datasource.driver-class-name=org.h2.Driver
 spring.datasource.username=sa
 spring.datasource.password=