serialize and deserialize from flatbuffers to and from bytearray

Question

hi stackoverflow community :)

i want create a flatbuffers object in java which i can serialize to a byte array, and later deserialize back in the java object. i work the first time with flatbuffers and i can't initialised a java object. my way step by step:

write a scheme
compile this with the flatbuffers compiler into a java class
import the flatbuffers class from github
try to build a java object

Here is my code for step 4:

FlatBufferBuilder fbb = new FlatBufferBuilder(1);
int str = fbb.createString("Dummy");
Monster.startPerson(fbb);
Monster.addName(fbb, str);
int p = Person.endPerson(fbb);

Maybe someone can post a simple example to creating a flatbuffers object, and how to serialize and deserialize to and from bytearray?

Hope for an answer and best regards,

Paul

http://google.github.io/flatbuffers/

score 5 · Accepted Answer · answered Oct 23 '14 at 11:02

5

a answer on the google group page: https://groups.google.com/forum/#!topic/flatbuffers/FZBDMd9m0hE

answered Oct 23 '14 at 11:02

Pa Rö

449
1
6
18

How would you de-serialize it from byte array to FlatBuffer. Answer on this page doesn't cover de-serializing case. – Tariq Oct 05 '15 at 14:09

MashiMaro · Answer 2 · 2015-11-10T15:29:28.377

2

Serialize

FlatBufferBuilder fbb = new FlatBufferBuilder();
int str = fbb.createString("MyMonster");
Monster.startMonster(fbb);
Monster.addName(fbb, str);
int mon = Monster.endMonster(fbb); 
fbb.finish(mon);   
byte[] data = fbb.sizedByteArray();

Deserialzie

ByteBuffer buff = ByteBuffer.wrap(data);
Monstermonster monster = Monster.getRootAsMonster(buff);
System.out.println(monster.name());

Hope this help.

edited Nov 10 '15 at 15:29

answered Nov 05 '15 at 15:31

MashiMaro

39
7

2

`fbb.sizedByteArray()` does not work due to missing `fbb.finish()` call. See my answer. – Volkan Yazıcı Nov 10 '15 at 10:08
Ah! I forgot. Thank you. – MashiMaro Nov 10 '15 at 15:29

score 2 · Answer 3 · answered Nov 10 '15 at 10:05

Consider you have the following FlatBuffers schema:

table ServiceException {
    message:string;
}

After compiling this schema with flatc to generate Java classes, you can create a ServiceException instance and convert it into a byte[] as follows:

FlatBufferBuilder fbb = new FlatBufferBuilder();
int messagePosition = fbb.createString("something bad happened");
int serviceExceptionPosition = ServiceException.createServiceException(fbb, messagePosition);
fbb.finish(serviceExceptionPosition);
byte[] outputBytes = fbb.sizedByteArray();

Next, you convert the generated outputBytes back into a ServiceException instance:

ByteBuffer inputByteBuffer = ByteBuffer.wrap(outputBytes);
ServiceException serviceException = ServiceException.getRootAsServiceException(inputByteBuffer);

.sizedByteArray() instead of .byteBuffer() saved my day :) Thanks! — Anton Shkurenko, Apr 06 '19 at 18:14

serialize and deserialize from flatbuffers to and from bytearray

3 Answers3