This is a part of an online Codename One course published around 2017 see it all for free at https://debugagent.com/series/cn1

1. Creating a Facebook Clone - Part XVIII
All media objects e.g. images, videos etc. are stored in the `Media` `Entity`.
This is pretty convenient as it lets us store media files in the database under a separate database table (which would be better for performance).

2. © Codename One 2017 all rights reserved
Pros Con
Clustering Large Database
Reasonable Performance Performance Could be Challenging
Simple Simple unless we scale
There are pros and cons for storing media in a database
A pro would be that it works with clustering as data is in the database and not on a specific server file.
However, it might make the database too large and harder to back up.
Performance is more complicated. It should be reasonable as long as table is separate. Historically performance of blob's in the database was pretty bad and there might
be issues in some deployments or some database types. So this might be challenging
Both approaches would be simple unless scaling is involved in which case we’d need to store files somewhere…
There is a common alternative of using a service dedicated to hosting files either home grown or in the cloud (e.g. S3). Since the Media object is separate it makes sense
to have it anyway and if we choose to use such a service we can include the file key for the cloud object instead of the actual media file.

3. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
The Media object itself is pretty simple.
Just like the User object we use a UUID to represent a Media object

4. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
This is the file name used when uploading which might be relevant if we let the user browse the files he uploaded in the future

5. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
The time stamp when the media was uploaded, using long makes this simpler to work with although date might be more convenient in a database

6. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
Role can be used to indicate the purpose of the image e.g. it can be avatar to indicate the image serves as an avatar

7. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
Visibility is the privacy scope of the image e.g. friends would indicate only friends can see the image whereas public would indicate it's visible to everyone

8. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
This is the user that uploaded this media object

9. @Entity
public class Media {
@Id
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
@ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
Media
The data is marked as a Lob which lets us store relatively large objects. Notice that there is still a limit on file upload size enforced by the webservice support in spring
boot

10. @ManyToOne
private User owner;
@Lob
private byte[] data;
public Media() {
id = UUID.randomUUID().toString();
}
public MediaDAO getDAO() {
return new MediaDAO(id, filename, date, role, mimeType, visibility,
owner.getDAO(), data);
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getFilename() {
return filename;
}
public void setFilename(String filename) {
Media
The media object has a DAO as well, it lets us pass the media data back and forth through the service layer

11. return mimeType;
}
public void setMimeType(String mimeType) {
this.mimeType = mimeType;
}
public byte[] getData() {
return data;
}
public void setData(byte[] data) {
this.data = data;
}
public String getVisibility() {
return visibility;
}
public void setVisibility(String visibility) {
this.visibility = visibility;
}
public User getOwner() {
return owner;
}
public void setOwner(User owner) {
this.owner = owner;
}
}
Media
As you can see the rest of the code is only getters and setters, nothing much.
The object is relatively simple and only contains one small dependency: MediaDAO. We could potentially enhance it with additional data such as description, tagging and
even auto-generated content based on image recognition. But for now that’s enough.

12. public interface MediaRepository extends CrudRepository<Media, String> {
}
MediaRepository
Before we go into the MediaDAO we also need to mention the CrudRepository interface for this class. It's simple as we don't need any queries at this point.

13. public class MediaDAO {
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
private UserDAO owner;
private byte[] data;
public MediaDAO() {
}
public MediaDAO(String id, String filename, long date, String role,
String mimeType, String visibility, UserDAO owner,
byte[] data) {
this.id = id;
this.filename = filename;
this.date = date;
this.role = role;
this.mimeType = mimeType;
this.visibility = visibility;
MediaDAO
Now that we got this out of the way we can look at the DAO, it's trivial too.
The fields map directly to the fields of the Media class in this case

14. public class MediaDAO {
private String id;
private String filename;
private long date;
private String role;
private String mimeType;
private String visibility;
private UserDAO owner;
private byte[] data;
public MediaDAO() {
}
public MediaDAO(String id, String filename, long date, String role,
String mimeType, String visibility, UserDAO owner,
byte[] data) {
this.id = id;
this.filename = filename;
this.date = date;
this.role = role;
this.mimeType = mimeType;
this.visibility = visibility;
MediaDAO
The one obvious exception is the UserDAO object which uses the DAO type instead of the User type

15. private String mimeType;
private String visibility;
private UserDAO owner;
private byte[] data;
public MediaDAO() {
}
public MediaDAO(String id, String filename, long date, String role,
String mimeType, String visibility, UserDAO owner,
byte[] data) {
this.id = id;
this.filename = filename;
this.date = date;
this.role = role;
this.mimeType = mimeType;
this.visibility = visibility;
this.owner = owner;
this.data = data;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
MediaDAO
As we did with the User object we have a default constructor and a convenience constructor. Both of these were generated by the IDE’s completion suggestion.

16. }
public String getMimeType() {
return mimeType;
}
public void setMimeType(String mimeType) {
this.mimeType = mimeType;
}
public String getVisibility() {
return visibility;
}
public void setVisibility(String visibility) {
this.visibility = visibility;
}
public byte[] getData() {
return data;
}
public void setData(byte[] data) {
this.data = data;
}
public UserDAO getOwner() {
return owner;
}
public void setOwner(UserDAO owner) {
this.owner = owner;
}
MediaDAO
The rest of the code is just auto-generated getters & setters. Nothing else. And with that we conclude the media object/entity.