Thank you Dave, I appreciate it. I'll give those a shot and let you know
how it goes.
-Gary
On Feb 18, 2014 6:45 PM, "Dave McAlpin" <dmcal...@inome.com> wrote:
> Here are some utility functions we've used for serialization to and from
> JSON. Something similar should work for binary.
>
>
>
> public <T> String avroEncodeAsJson(Class<T> clazz, Object object) {
>
> String avroEncodedJson = null;
>
> try {
>
> if (object == null || !(object instanceof SpecificRecord)) {
>
> return null;
>
> }
>
> T record = (T) object;
>
> Schema schema = ((SpecificRecord) record).getSchema();
>
> ByteArrayOutputStream out = new ByteArrayOutputStream();
>
> Encoder e = EncoderFactory.get().jsonEncoder(schema, out);
>
> SpecificDatumWriter<T> w = new SpecificDatumWriter<T>(clazz);
>
> w.write(record, e);
>
> e.flush();
>
> avroEncodedJson = new String(out.toByteArray());
>
> } catch (IOException e) {
>
> e.printStackTrace();
>
> }
>
>
>
> return avroEncodedJson;
>
> }
>
>
>
> public <T> T jsonDecodeToAvro(String inputString, Class<T> className,
> Schema schema) {
>
> T returnObject = null;
>
> try {
>
> JsonDecoder jsonDecoder = DecoderFactory.get().jsonDecoder(schema,
> inputString);
>
> SpecificDatumReader<T> reader = new
> SpecificDatumReader<T>(className);
>
> returnObject = reader.read(null, jsonDecoder);
>
> } catch (IOException e) {
>
> e.printStackTrace();
>
> }
>
>
>
> return returnObject;
>
> }
>
>
>
> Dave
>
>
>
> *From:* flaming.ze...@gmail.com [mailto:flaming.ze...@gmail.com] *On
> Behalf Of *Gary Steelman
> *Sent:* Tuesday, February 18, 2014 4:21 PM
> *To:* user@avro.apache.org
> *Subject:* General-Purpose Serialization and Deserialization for
> Avro-Generated SpecificRecords
>
>
>
> Hi all,
>
> Here's my use case: I've got a bunch of different Java objects generated
> from Avro schema files. So the class definition headers look something like
> this: public class MyObject extends
> org.apache.avro.specific.SpecificRecordBase implements
> org.apache.avro.specific.SpecificRecord. I've got many other types than
> MyObject too. I need to write a method which can serialize (from MyObject
> or another class to byte[]) and deserialize (from byte[] to MyObject or
> another class) in memory (not writing to disk).
>
> I couldn't figure out how to write one method to handle it for
> SpecificRecord, so I tired serializing/deserializing these things as
> GenericRecord instead:
>
> public static byte[] serializeFromAvro(GenericRecord gr) {
> try {
> DatumWriter<GenericRecord> writer2 = new
> GenericDatumWriter<GenericRecord>(gr.getSchema());
> ByteArrayOutputStream bao2 = new ByteArrayOutputStream();
> BinaryEncoder encoder2 =
> EncoderFactory.get().directBinaryEncoder(bao2, null);
> writer2.write(gr, encoder2);
> byte[] avroBytes2 = bao2.toByteArray();
> return avroBytes2;
> } catch (IOException e) {
> LOG.debug(e);
> return null;
> }
> }
>
> // Here I use a DataType enum and the AvroSchemaFactory to quickly
> retrieve a Schema object for a supported DataType.
>
> public static GenericRecord deserializeFromAvro(byte[] avroBytes,
> DataType dataType) {
> try {
> Schema schema = AvroSchemaFactory.getInstance().getSchema(dataType);
> DatumReader<GenericRecord> reader2 = new
> GenericDatumReader<GenericRecord>(schema);
> ByteArrayInputStream bai2 = new ByteArrayInputStream(avroBytes);
> BinaryDecoder decoder2 =
> DecoderFactory.get().directBinaryDecoder(bai2, null);
> GenericRecord gr2 = reader2.read(null, decoder2);
> return gr2;
> } catch (Exception e) {
> LOG.debug(e);
> return null;
> }
> }
>
> And use them like such:
>
> // Remember MyObject is the SpecificRecord implementing class.
>
> MyObject x = new MyObject();
>
> byte[] avroBytes = serializeFromAvro(x);
>
> MyObject x2 = (MyObject) deserializeFromAvro(avroBytes, DataType.MyObject);
>
> Which results in this:
> java.lang.ClassCastException: org.apache.avro.generic.GenericData$Record
> cannot be cast to datatypes.generated.avro.MyObject
>
> Is there an easier way to achieve my use case, or some way I can fix my
> methods to allow the sort of behavior I want?
>
> Thanks,
>
> Gary
>
