Java Serializable Object to Byte Array

Question

Let\'s say I have a serializable class AppMessage.

I would like to transmit it as byte[] over sockets to another machine where it is rebuil

Answer 1

This is just an optimized code form of the accepted answer in case anyone wants to use this in production :

    public static void byteArrayOps() throws IOException, ClassNotFoundException{

    String str="123";
     byte[] yourBytes = null;

    // Convert to byte[]

    try(ByteArrayOutputStream bos = new ByteArrayOutputStream();
            ObjectOutputStream out =  new ObjectOutputStream(bos);) {


      out.writeObject(str);
      out.flush();
      yourBytes = bos.toByteArray();

    } finally {

    }

    // convert back to Object

    try(ByteArrayInputStream bis = new ByteArrayInputStream(yourBytes);
            ObjectInput in = new ObjectInputStream(bis);) {

      Object o = in.readObject(); 

    } finally {

    }




}

Answer 2

In case you want a nice no dependencies copy-paste solution. Grab the code below.

Example

MyObject myObject = ...

byte[] bytes = SerializeUtils.serialize(myObject);
myObject = SerializeUtils.deserialize(bytes);

Source

import java.io.*;

public class SerializeUtils {

    public static byte[] serialize(Serializable value) throws IOException {
        ByteArrayOutputStream out = new ByteArrayOutputStream();

        try(ObjectOutputStream outputStream = new ObjectOutputStream(out)) {
            outputStream.writeObject(value);
        }

        return out.toByteArray();
    }

    public static <T extends Serializable> T deserialize(byte[] data) throws IOException, ClassNotFoundException {
        try(ByteArrayInputStream bis = new ByteArrayInputStream(data)) {
            //noinspection unchecked
            return (T) new ObjectInputStream(bis).readObject();
        }
    }
}

Answer 3

Spring Framework org.springframework.util.SerializationUtils

byte[] data = SerializationUtils.serialize(obj);

Answer 4

I would like to transmit it as byte[] over sockets to another machine

// When you connect
ObjectOutputStream oos = new ObjectOutputStream(socket.getOutputStream());
// When you want to send it
oos.writeObject(appMessage);

where it is rebuilt from the bytes received.

// When you connect
ObjectInputStream ois = new ObjectInputStream(socket.getInputStream());
// When you want to receive it
AppMessage appMessage = (AppMessage)ois.readObject();

Answer 5

code example with java 8+:

public class Person implements Serializable {

private String lastName;
private String firstName;

public Person() {
}

public Person(String firstName, String lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
}

public void setFirstName(String firstName) {
    this.firstName = firstName;
}

public String getFirstName() {
    return firstName;
}

public String getLastName() {
    return lastName;
}

public void setLastName(String lastName) {
    this.lastName = lastName;
}

@Override
public String toString() {
    return "firstName: " + firstName + ", lastName: " + lastName;
}
}


public interface PersonMarshaller {
default Person fromStream(InputStream inputStream) {
    try (ObjectInputStream objectInputStream = new ObjectInputStream(inputStream)) {
        Person person= (Person) objectInputStream.readObject();
        return person;
    } catch (IOException | ClassNotFoundException e) {
        System.err.println(e.getMessage());
        return null;
    }
}

default OutputStream toStream(Person person) {
    try (OutputStream outputStream = new ByteArrayOutputStream()) {
        ObjectOutput objectOutput = new ObjectOutputStream(outputStream);
        objectOutput.writeObject(person);
        objectOutput.flush();
        return outputStream;
    } catch (IOException e) {
        System.err.println(e.getMessage());
        return null;
    }

}

}

Answer 6

Another interesting method is from com.fasterxml.jackson.databind.ObjectMapper

byte[] data = new ObjectMapper().writeValueAsBytes(JAVA_OBJECT_HERE)

Maven Dependency

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
</dependency>