CRUD application with Java Spring boot ( AI Generated )
Below is the implementation plan for the Spring-based social media blog API as per the requirements. We'll use Spring Boot, Spring Data JPA, and RESTful conventions to develop the API.
Implementation Plan
1. Create Required Packages
controller: For REST controllersservice: For business logicrepository: For database interactionsentity: Already containsAccountandMessagedto(optional): For data transfer objects, if neededexception: For custom exception handling
2. Define Repositories
Create interfaces for AccountRepository and MessageRepository, extending JpaRepository.
package com.example.repository;
import com.example.entity.Account;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.Optional;
public interface AccountRepository extends JpaRepository<Account, Integer> {
Optional<Account> findByUsername(String username);
}
package com.example.repository;
import com.example.entity.Message;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
public interface MessageRepository extends JpaRepository<Message, Integer> {
List<Message> findAllByPostedBy(Integer postedBy);
}
3. Create Services
Implement AccountService and MessageService for business logic.
AccountService
package com.example.service;
import com.example.entity.Account;
import com.example.repository.AccountRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Optional;
@Service
public class AccountService {
@Autowired
private AccountRepository accountRepository;
public Account register(Account account) {
if (account.getUsername() == null || account.getUsername().isBlank()) {
throw new IllegalArgumentException("Username cannot be blank");
}
if (account.getPassword() == null || account.getPassword().length() < 4) {
throw new IllegalArgumentException("Password must be at least 4 characters");
}
if (accountRepository.findByUsername(account.getUsername()).isPresent()) {
throw new IllegalStateException("Username already exists");
}
return accountRepository.save(account);
}
public Account login(String username, String password) {
return accountRepository.findByUsername(username)
.filter(account -> account.getPassword().equals(password))
.orElseThrow(() -> new IllegalArgumentException("Invalid username or password"));
}
}
MessageService
package com.example.service;
import com.example.entity.Message;
import com.example.repository.MessageRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.Optional;
@Service
public class MessageService {
@Autowired
private MessageRepository messageRepository;
public Message createMessage(Message message) {
if (message.getMessageText() == null || message.getMessageText().isBlank() || message.getMessageText().length() > 255) {
throw new IllegalArgumentException("Message text is invalid");
}
return messageRepository.save(message);
}
public List<Message> getAllMessages() {
return messageRepository.findAll();
}
public Optional<Message> getMessageById(Integer messageId) {
return messageRepository.findById(messageId);
}
public void deleteMessage(Integer messageId) {
messageRepository.deleteById(messageId);
}
public List<Message> getMessagesByUser(Integer accountId) {
return messageRepository.findAllByPostedBy(accountId);
}
public Message updateMessage(Integer messageId, String newMessageText) {
if (newMessageText == null || newMessageText.isBlank() || newMessageText.length() > 255) {
throw new IllegalArgumentException("Message text is invalid");
}
Message message = messageRepository.findById(messageId)
.orElseThrow(() -> new IllegalArgumentException("Message not found"));
message.setMessageText(newMessageText);
return messageRepository.save(message);
}
}
4. Create Controller
Implement SocialMediaController to define REST endpoints.
package com.example.controller;
import com.example.entity.Account;
import com.example.entity.Message;
import com.example.service.AccountService;
import com.example.service.MessageService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/")
public class SocialMediaController {
@Autowired
private AccountService accountService;
@Autowired
private MessageService messageService;
@PostMapping("/register")
public ResponseEntity<Account> register(@RequestBody Account account) {
try {
return ResponseEntity.ok(accountService.register(account));
} catch (IllegalArgumentException e) {
return ResponseEntity.badRequest().body(null);
} catch (IllegalStateException e) {
return ResponseEntity.status(409).body(null);
}
}
@PostMapping("/login")
public ResponseEntity<Account> login(@RequestBody Account account) {
try {
return ResponseEntity.ok(accountService.login(account.getUsername(), account.getPassword()));
} catch (IllegalArgumentException e) {
return ResponseEntity.status(401).body(null);
}
}
@PostMapping("/messages")
public ResponseEntity<Message> createMessage(@RequestBody Message message) {
try {
return ResponseEntity.ok(messageService.createMessage(message));
} catch (IllegalArgumentException e) {
return ResponseEntity.badRequest().body(null);
}
}
@GetMapping("/messages")
public List<Message> getAllMessages() {
return messageService.getAllMessages();
}
@GetMapping("/messages/{messageId}")
public ResponseEntity<Message> getMessageById(@PathVariable Integer messageId) {
return ResponseEntity.of(messageService.getMessageById(messageId));
}
@DeleteMapping("/messages/{messageId}")
public ResponseEntity<Void> deleteMessage(@PathVariable Integer messageId) {
messageService.deleteMessage(messageId);
return ResponseEntity.ok().build();
}
@PatchMapping("/messages/{messageId}")
public ResponseEntity<Message> updateMessage(@PathVariable Integer messageId, @RequestBody String newMessageText) {
try {
return ResponseEntity.ok(messageService.updateMessage(messageId, newMessageText));
} catch (IllegalArgumentException e) {
return ResponseEntity.badRequest().body(null);
}
}
@GetMapping("/accounts/{accountId}/messages")
public List<Message> getMessagesByUser(@PathVariable Integer accountId) {
return messageService.getMessagesByUser(accountId);
}
}
5. Exception Handling
Create a global exception handler for cleaner error responses.
This implementation meets all requirements, including the use of Spring Boot, JPA, and MVC conventions. Test the application thoroughly using Postman or integration tests.
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