자바 직렬화 란 무엇입니까?

package constxiong.interview;
 
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
 
/**
 * 测试序列化，反序列化
 * @author ConstXiong
 * @date 2019-06-17 09:31:22
 */
public class TestSerializable implements Serializable {
 
	private static final long serialVersionUID = 5887391604554532906L;
	
	private int id;
	
	private String name;
 
	public TestSerializable(int id, String name) {
		this.id = id;
		this.name = name;
	}
	
	@Override
	public String toString() {
		return "TestSerializable [id=" + id + ", name=" + name + "]";
	}
 
	@SuppressWarnings("resource")
	public static void main(String[] args) throws IOException, ClassNotFoundException {
		//序列化
		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("TestSerializable.obj"));
		oos.writeObject("测试序列化");
		oos.writeObject(618);
		TestSerializable test = new TestSerializable(1, "ConstXiong");
		oos.writeObject(test);
		
		//反序列化
		ObjectInputStream ois = new ObjectInputStream(new FileInputStream("TestSerializable.obj"));
		System.out.println((String)ois.readObject());
		System.out.println((Integer)ois.readObject());
		System.out.println((TestSerializable)ois.readObject());
	}
 
}

测试序列化
618
TestSerializable [id=1, name=ConstXiong]