Several serialization implementation methods come with java, Writable, Avro

 

package org.hdp.practice.serial;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

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;

public class Avro {

	public static void main(String[] args) throws Exception{
		// readAvro ();
		//writeJavaObject();
		readWriteableObject();
	}
	
	static void writeWriteableObject() throws Exception{
		FileOutputStream fos = new FileOutputStream("D:/tmp/users.wobj");
		DataOutputStream dos = new DataOutputStream(fos);
		
		MyUser user1 = new MyUser();
		user1.setName("Alyssa");
		user1.setFavoriteNumber(256);
		user1.setFavoriteColor("yellow");
		user1.write(dos);
		
		MyUser user2 = new MyUser("Ben", 7, "red");
		user2.write(dos);

		dos.close();
		fos.close();
	}
	
	static void readWriteableObject() throws Exception{
		FileInputStream fis = new FileInputStream("D:/tmp/users.wobj");
		DataInputStream dis = new DataInputStream(fis);
		
		MyUser user1 = new MyUser();
		user1.readFields(dis);
		System.out.println(user1);
		
		MyUser user2 = new MyUser();
		user2.readFields(dis);
		System.out.println(user2);
		
		dis.close();
	}
	
	
	static void writeJavaObject() throws Exception{
		User user1 = new User();
		user1.setName("Alyssa");
		user1.setFavoriteNumber(256);

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

		User user3 = User.newBuilder()
		             .setName("Charlie")
		             .setFavoriteColor("blue")
		             .setFavoriteNumber (null)
		             .build();
		
		FileOutputStream fos = new FileOutputStream("D:/tmp/users.jobj");
		ObjectOutputStream oos = new ObjectOutputStream(fos);
		oos.writeObject (user1);
		oos.writeObject (user2);
		oos.writeObject(user3);
		oos.close();
		fos.close();
	}
	
	static void readJavaObject() throws Exception{
		FileInputStream fis = new FileInputStream("D:/tmp/users.jobj");
		ObjectInputStream ois = new ObjectInputStream(fis);

		User user =  (User)ois.readObject();
		System.out.println(user);
		
		User user1 =  (User)ois.readObject();
		System.out.println(user1);
		
		User user2 =  (User)ois.readObject();
		System.out.println(user2);
		
		ois.close();
		fis.close();
	}
	
	
	static void writeAvro() throws Exception{
		User user1 = new User();
		user1.setName("Alyssa");
		user1.setFavoriteNumber(256);

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

		User user3 = User.newBuilder()
		             .setName("Charlie")
		             .setFavoriteColor("blue")
		             .setFavoriteNumber (null)
		             .build();

		DatumWriter<User> userDatumWriter = new SpecificDatumWriter<User>(User.class);
		DataFileWriter<User> dataFileWriter = new DataFileWriter<User>(userDatumWriter);
		dataFileWriter.create(user1.getSchema(), new File("D:/tmp/users.avro"));
		dataFileWriter.append(user1);
		dataFileWriter.append(user2);
		dataFileWriter.append(user3);
		dataFileWriter.close();
	}
	
	static void readAvro() throws Exception{
		File file = new File("D:/tmp/users.avro");
		DatumReader<User> userDatumReader = new SpecificDatumReader<User>(User.class);
		DataFileReader<User> dataFileReader = new DataFileReader<User>(file, userDatumReader);
		User user = null;
		while (dataFileReader.hasNext()) {
			user = dataFileReader.next(user);
			System.out.println(user);
		}
		dataFileReader.close();
	}

}