Add Post module

src/main/java/com/openisle/service/PostService.java

@@ -0,0 +1,38 @@
+package com.openisle.service;
+
+import com.openisle.model.Post;
+import com.openisle.model.User;
+import com.openisle.repository.PostRepository;
+import com.openisle.repository.UserRepository;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+@Service
+@RequiredArgsConstructor
+public class PostService {
+    private final PostRepository postRepository;
+    private final UserRepository userRepository;
+
+    public Post createPost(String username, String title, String content) {
+        User author = userRepository.findByUsername(username)
+                .orElseThrow(() -> new IllegalArgumentException("User not found"));
+        Post post = new Post();
+        post.setTitle(title);
+        post.setContent(content);
+        post.setAuthor(author);
+        return postRepository.save(post);
+    }
+
+    public Post getPost(Long id) {
+        Post post = postRepository.findById(id)
+                .orElseThrow(() -> new IllegalArgumentException("Post not found"));
+        post.setViews(post.getViews() + 1);
+        return postRepository.save(post);
+    }
+
+    public List<Post> listPosts() {
+        return postRepository.findAll();
+    }
+}