Avro数据格式学习及其Java操作

import org.apache.avro.file.DataFileReader;
import org.apache.avro.file.DataFileWriter;
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 java.io.File;

/**
 * Hello world!
 *
 */
public class Main
{
    public static void main( String[] args )
    {
        User user1 = new User();

        user1.setName("Alyssa");
        user1.setFavoriteNumber(256);
        // Leave favorite color null

        // Alternate constructor
        User user2 = new User("Ben", 7, "red");

        // Construct via builder
        User user3 = User.newBuilder()
                .setName("Charlie")
                .setFavoriteColor("blue")
                .setFavoriteNumber(null)
                .build();
        // Serialize user1, user2 and user3 to disk
        DatumWriter<User> userDatumWriter = new SpecificDatumWriter<User>(User.class);
        DataFileWriter<User> dataFileWriter = new DataFileWriter<User>(userDatumWriter);
        try {
            dataFileWriter.create(user1.getSchema(), new File("users.avro"));
            dataFileWriter.append(user1);
            dataFileWriter.append(user2);
            dataFileWriter.append(user3);
            dataFileWriter.close();
        }catch (Exception e){
            System.out.println();
        }

        //反序列化
        // Deserialize Users from disk
        DatumReader<User> userDatumReader = new SpecificDatumReader<User>(User.class);

        // 使用这种方式可以避免因为对象太多而造成的对 gc  的不良影响。
        User user = null;
        try{
            DataFileReader<User> dataFileReader = new DataFileReader<User>( new File("users.avro"),
                    userDatumReader);
            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);
            }
        }catch (Exception e){
            System.out.println(e);
        }
    }
}