JAVA object to byte array conversion method

How to convert an object to byte array in JAVA.

The easiest way to convert an object to byte array is to use the Object Serialization ObjectOutputStream.
However, there is a problem that object serialization is compatible only with Java.
Object serialization cannot be used for socket communication with heterogeneous (c language, .NET, etc.).

So the method I found is to use ByteArrayOutputStream.

Below is an example of converting a class object configured with 16 bytes to byte[].
To implement it in a functional form for general use, it would be necessary to use the concept of Java reflection.

 

public class ProtocolDto {
	public byte sender;
	public byte receiver;
	public short cmd;
	public short error;
	public short warning;
	public int reserved;
	public int data_length;
}

 

ProtocolDto protocolDto = new ProtocolDto();

// Object to Byte[] 변환
byte[] dtoByteArray = null;

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
DataOutputStream dataOutputStream = new DataOutputStream(byteArrayOutputStream);
try {
	dataOutputStream.writeByte(protocolDto.sender);
	dataOutputStream.writeByte(protocolDto.receiver);
	dataOutputStream.writeShort(protocolDto.cmd);
	dataOutputStream.writeShort(protocolDto.error);
	dataOutputStream.writeShort(protocolDto.warning);
	dataOutputStream.writeInt(protocolDto.reserved);
	dataOutputStream.writeInt(protocolDto.data_length);
	dataOutputStream.flush();
	dtoByteArray = byteArrayOutputStream.toByteArray();
} finally {
	dataOutputStream.close();
	byteArrayOutputStream.close();
}

// Result 16bytes
System.out.println(dtoByteArray.length);