package it.dtk;
import java.io.File;
import java.io.IOException;
import org.apache.avro.Schema;
import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
import org.apache.avro.generic.GenericData;
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.DatumWriter;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;
import it.dtk.avro.User;
public class SchemaExample {
/**
* @throws IOException
* example using bean schema defined in it.dreamslair.avro package
*/
public static void schemaExample() throws IOException {
User user1 = new User();
user1.setName("Alyssa");
user1.setFavoriteNumber(256);
// Leave favorite color null
// Alternate constructor
User user2 = new User("Ben", 7, "red");
//this print the bean as it is saved in the datuwriter
System.out.println(user1.toString());
// Construct via builder
User user3 = User.newBuilder().setName("Charlie")
.setFavoriteColor("blue").setFavoriteNumber(null).build();
// Serialize user1 and user2 to disk
File file = new File("users.avro");
DatumWriter<User> userDatumWriter = new SpecificDatumWriter<User>(
User.class);
DataFileWriter<User> dataFileWriter = new DataFileWriter<User>(
userDatumWriter);
dataFileWriter.create(user1.getSchema(), new File("users.avro"));
dataFileWriter.append(user1);
dataFileWriter.append(user2);
dataFileWriter.append(user3);
dataFileWriter.append(user1);
dataFileWriter.append(user2);
dataFileWriter.append(user3);
dataFileWriter.append(user1);
dataFileWriter.append(user2);
dataFileWriter.append(user3);
dataFileWriter.append(user1);
dataFileWriter.append(user2);
dataFileWriter.append(user3);
dataFileWriter.close();
// Deserialize Users from disk
DatumReader<User> userDatumReader = new SpecificDatumReader<User>(
User.class);
DataFileReader<User> dataFileReader = new DataFileReader<User>(file,
userDatumReader);
User user = null;
while (dataFileReader.hasNext()) {
// Reuse user object by passing it to next(). This saves us from
// allocating and garbage collecting many objects for files with
// many items.
user = dataFileReader.next(user);
System.out.println(user);
}
}
public static void main(String[] args) {
try {
schemaExample();
} catch (IOException e) {
e.printStackTrace();
}
}
}