Question

I am trying to use Protocol buffers to store serialized data in Database for a web application built in java.

I have created .proto files and compiled them to get the generated classes. Also I can build the message objects using the setters & finally build() method. But to store it to database, I need serialized data as byte[] or byte buffers. How do I finally get that from the message instances ??

    import com.paratha.serializers.protocolbuffers.CommentProto.Comment;

    Comment.Builder comment=Comment.newBuilder();
    comment.setCommentBody("This is the first comment!").setUserId(32433).build();  

How do I get the serialized data from here to write to database ?

Answer 1

Google have made it very easy 🙂 :

MyProtocolBufferObject myObject = MyProtocolBufferObject.newBuilder().setName("bob").build();
byte[] bytes = myObject.toByteArray();

Edit
With your example:

Comment.Builder commentBuilder=Comment.newBuilder();
Comment comment = commentBuilder.setCommentBody("This is the first comment!").setUserId(32433).build();
byte[] bytes = comment.toByteArray();

Note that when you call the newBuilder() method you are getting an instance of Comment.Builder, not an instance of Comment. It is only when you call the Comment.Builder‘s build() method that you get an instance of Comment.