Json to Avro

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericDatumReader;
import org.apache.avro.generic.GenericDatumWriter;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.io.Encoder;
import org.apache.avro.io.EncoderFactory;

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.InputStream;
import java.io.ByteArrayInputStream;


public class JasonToAvro {

/**
* @param args
* @throws Exception 
*/
public static void main(String[] args) throws Exception {

String json = "{\"username\":\"miguno\",\"tweet\":\"Rock: Nerf paper, scissors is fine.\",\"timestamp\": 1366150681 }";
String schemastr ="{ \"type\" : \"record\", \"name\" : \"twitter_schema\", \"namespace\" : \"com.miguno.avro\", \"fields\" : [ { \"name\" : \"username\", \"type\" : \"string\", \"doc\"  : \"Name of the user account on Twitter.com\" }, { \"name\" : \"tweet\", \"type\" : \"string\", \"doc\"  : \"The content of the user's Twitter message\" }, { \"name\" : \"timestamp\", \"type\" : \"long\", \"doc\"  : \"Unix epoch time in seconds\" } ], \"doc:\" : \"A basic schema for storing Twitter messages\" }";

byte[] avroByteArray = fromJasonToAvro(json,schemastr);

Schema schema = Schema.parse(schemastr);
DatumReader<Genericrecord> reader1 = new GenericDatumReader<Genericrecord>(schema);

Decoder decoder1 = DecoderFactory.get().binaryDecoder(avroByteArray, null);
GenericRecord result = reader1.read(null, decoder1);

System.out.println(result.get("username").toString());
System.out.println(result.get("tweet").toString());
System.out.println(result.get("timestamp"));

}

/**
* @param json
* @param schemastr
* @throws Exception 
*/
static byte[] fromJasonToAvro(String json, String schemastr) throws Exception {

InputStream input = new ByteArrayInputStream(json.getBytes());
DataInputStream din = new DataInputStream(input);

Schema schema = Schema.parse(schemastr);

Decoder decoder = DecoderFactory.get().jsonDecoder(schema, din);

DatumReader<Object> reader = new GenericDatumReader<Object>(schema);
Object datum = reader.read(null, decoder);


GenericDatumWriter<Object>  w = new GenericDatumWriter<Object>(schema);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

Encoder e = EncoderFactory.get().binaryEncoder(outputStream, null);

w.write(datum, e);
e.flush();

return outputStream.toByteArray();
}
}