The document discusses the implementation of posts, media, and comments for a Facebook clone application. Key points include: - A Post entity supports one media file per post, comments, likes, and attachments through relationships to other entities. - The PostDAO converts Post entities to plain Java objects for transferring data to and from the client. - The PostService allows creating and sharing posts to friends' newsfeeds through repositories for posts, users, newsfeeds, comments, and media. - The MediaService supports getting media attachments by ID, checking permissions and returning file data and metadata.

1. Creating a Facebook Clone - Part XXXVIII

2. Media
✦One media file per post
✦Most of the work is already done
✦Important: mySQL doesn’t support large blobs by
default. Had to add:
--max_allowed_packet=256M
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3. @ManyToOne
private User user;
private long date;
@Field
private String title;
@Field
private String content;
private String visibility;
private String styling;
@OneToMany
@OrderBy("date ASC")
private Set<Comment> comments;
@ManyToMany
private Set<Media> attachments;
@ManyToMany
private Set<User> likes;
public Post() {
Post (Entity)

4. public Post() {
id = UUID.randomUUID().toString();
}
public PostDAO getDAO() {
List<CommentDAO> commentsDAO = null;
if(comments != null && comments.size() > 0) {
commentsDAO = new ArrayList<>();
for(Comment c : comments) {
commentsDAO.add(c.getDAO());
}
}
Map<String, String> mediaIds = null;
if(attachments != null && attachments.size() > 0) {
mediaIds = new LinkedHashMap<>();
for(Media c : attachments) {
mediaIds.put(c.getId(), c.getMimeType());
}
}
return new PostDAO(id, user.getDAO(), date, title, content,
visibility, styling,
commentsDAO, User.toUserDAOList(likes), mediaIds);
}
Post (Entity)

5. public Post() {
id = UUID.randomUUID().toString();
}
public PostDAO getDAO() {
List<CommentDAO> commentsDAO = null;
if(comments != null && comments.size() > 0) {
commentsDAO = new ArrayList<>();
for(Comment c : comments) {
commentsDAO.add(c.getDAO());
}
}
Map<String, String> mediaIds = null;
if(attachments != null && attachments.size() > 0) {
mediaIds = new LinkedHashMap<>();
for(Media c : attachments) {
mediaIds.put(c.getId(), c.getMimeType());
}
}
return new PostDAO(id, user.getDAO(), date, title, content,
visibility, styling,
commentsDAO, User.toUserDAOList(likes), mediaIds);
}
Post (Entity)

6. public Post() {
id = UUID.randomUUID().toString();
}
public PostDAO getDAO() {
List<CommentDAO> commentsDAO = null;
if(comments != null && comments.size() > 0) {
commentsDAO = new ArrayList<>();
for(Comment c : comments) {
commentsDAO.add(c.getDAO());
}
}
Map<String, String> mediaIds = null;
if(attachments != null && attachments.size() > 0) {
mediaIds = new LinkedHashMap<>();
for(Media c : attachments) {
mediaIds.put(c.getId(), c.getMimeType());
}
}
return new PostDAO(id, user.getDAO(), date, title, content,
visibility, styling,
commentsDAO, User.toUserDAOList(likes), mediaIds);
}
Post (Entity)

7. public class PostDAO {
private String id;
private UserDAO user;
private long date;
private String title;
private String content;
private String visibility;
private String styling;
private List<CommentDAO> comments;
private List<UserDAO> likes;
private Map<String, String> attachments;
public PostDAO() {
}
public PostDAO(String id, UserDAO user, long date, String title,
String content, String visibility, String styling,
PostDAO

8. private List<UserDAO> likes;
private Map<String, String> attachments;
public PostDAO() {
}
public PostDAO(String id, UserDAO user, long date, String title,
String content, String visibility, String styling,
List<CommentDAO> comments, List<UserDAO> likes,
Map<String, String> attachments) {
this.id = id;
this.user = user;
this.date = date;
this.title = title;
this.content = content;
this.visibility = visibility;
this.styling = styling;
this.comments = comments;
this.likes = likes;
this.attachments = attachments;
}
PostDAO

9. @Service
public class PostService {
private static final int DAY = 24 * 60 * 60000;
@Autowired
private UserRepository users;
@Autowired
private PostRepository posts;
@Autowired
private NewsfeedRepository news;
@Autowired
private CommentRepository comments;
@Autowired
private MediaRepository medias;
@Autowired
PostService

10. }
return response;
}
public String post(String authToken, PostDAO pd) {
User u = users.findByAuthtoken(authToken).get(0);
Post p = new Post();
p.setContent(pd.getContent());
p.setDate(System.currentTimeMillis());
p.setStyling(pd.getStyling());
p.setTitle(pd.getTitle());
p.setUser(u);
p.setVisibility(pd.getVisibility());
if(pd.getAttachments() != null && !pd.getAttachments().isEmpty()) {
Set<Media> s = new HashSet<>();
for(String id : pd.getAttachments().keySet()) {
s.add(medias.findById(id).get());
}
p.setAttachments(s);
}
posts.save(p);
addPostToNewsfeed(u, p);
if(u.getFriends() != null) {
for(User c : u.getFriends()) {
PostService

11. }
return response;
}
public String post(String authToken, PostDAO pd) {
User u = users.findByAuthtoken(authToken).get(0);
Post p = new Post();
p.setContent(pd.getContent());
p.setDate(System.currentTimeMillis());
p.setStyling(pd.getStyling());
p.setTitle(pd.getTitle());
p.setUser(u);
p.setVisibility(pd.getVisibility());
if(pd.getAttachments() != null && !pd.getAttachments().isEmpty()) {
Set<Media> s = new HashSet<>();
for(String id : pd.getAttachments().keySet()) {
s.add(medias.findById(id).get());
}
p.setAttachments(s);
}
posts.save(p);
addPostToNewsfeed(u, p);
if(u.getFriends() != null) {
for(User c : u.getFriends()) {
PostService

12. }
return response;
}
public String post(String authToken, PostDAO pd) {
User u = users.findByAuthtoken(authToken).get(0);
Post p = new Post();
p.setContent(pd.getContent());
p.setDate(System.currentTimeMillis());
p.setStyling(pd.getStyling());
p.setTitle(pd.getTitle());
p.setUser(u);
p.setVisibility(pd.getVisibility());
if(pd.getAttachments() != null && !pd.getAttachments().isEmpty()) {
Set<Media> s = new HashSet<>();
for(String id : pd.getAttachments().keySet()) {
s.add(medias.findById(id).get());
}
p.setAttachments(s);
}
posts.save(p);
addPostToNewsfeed(u, p);
if(u.getFriends() != null) {
for(User c : u.getFriends()) {
PostService

13. @RequestMapping(value="/public/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getPublic(@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getPublicMedia(id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
}
return ResponseEntity.notFound().build();
}
@RequestMapping(value="/all/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getAll(
@RequestParam(name="auth", required=true) String auth,
@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getMedia(auth, id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
MediaService

14. @RequestMapping(value="/public/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getPublic(@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getPublicMedia(id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
}
return ResponseEntity.notFound().build();
}
@RequestMapping(value="/all/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getAll(
@RequestParam(name="auth", required=true) String auth,
@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getMedia(auth, id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
MediaService

15. @RequestMapping(value="/public/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getPublic(@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getPublicMedia(id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
}
return ResponseEntity.notFound().build();
}
@RequestMapping(value="/all/{id:.+}", method=RequestMethod.GET)
public ResponseEntity<byte[]> getAll(
@RequestParam(name="auth", required=true) String auth,
@PathVariable("id") String id)
throws PermissionException {
MediaDAO av = medias.getMedia(auth, id);
if(av != null) {
return ResponseEntity.ok().
contentType(MediaType.valueOf(av.getMimeType())).
contentLength(av.getData().length).
body(av.getData());
MediaService