Is it possible to parse protobuf in a generic fashion in Java?
I have looked into GeneratedMessage and could not find a way to parse any PB byte buffer into a GeneratedMessage.
Essentially, I am trying to parse a PB byte buffer into GeneratedMessage and then I would use reflection to detect fields inside it.
You can use UnknownFieldSet to parse generic protobuf messages.
Then you can get individual fields using provided methods (e.g. asMap(), hasField(), getField())
E.g. (data taken from this question):
byte[] msg = new byte[] { 0x0a, 0x10, 0x08, 0x7f, (byte)0x8a, 0x01, 0x04, 0x08, 0x02, 0x10, 0x03, (byte)0x92, 0x01, 0x04, 0x08, 0x02, 0x10, 0x03, 0x18, 0x01};
UnknownFieldSet eee = UnknownFieldSet.parseFrom(msg);
System.out.println(eee.toString());
Giving:
1: {
1: 127
17: {
1: 2
2: 3
}
18: {
1: 2
2: 3
}
}
3: 1
Here is another way to generically parse a .desc file:
FileInputStream fin = new FileInputStream(descPath);
DescriptorProtos.FileDescriptorSet set = DescriptorProtos.FileDescriptorSet.parseFrom(fin);
List<FileDescriptor> dependencyFileDescriptorList = new ArrayList<>();
for(int i=0; i<set.getFileCount()-1;i++) {
dependencyFileDescriptorList.add(Descriptors.FileDescriptor.buildFrom(set.getFile(i), new Descriptors.FileDescriptor[] {}));
}
FileDescriptor desc = Descriptors.FileDescriptor.buildFrom(set.getFile(set.getFileCount()-1), dependencyFileDescriptorList.toArray(new FileDescriptor[0]));