Otra posible solución puede ser definir un conjunto de métodos privados dentro de su clase Serializable que utiliza las instancias de la clase de terceros. Estos métodos especiales son parte de un contrato de devolución de llamada especial que ofrece el sistema de serialización. durante el proceso de serialización/deserialización. Sus firmas deben ser como:
private void writeObject(ObjectOutputStream os) {
// your code for saving the third party variables
}
private void readObject(ObjectInputStream is) {
// your code to read the third party state, create a new ThirdParty instance,
// and assign it to your class.
}
Este ejemplo aclara esta idea:
public class MyClass implements Serializable
{
transient private ThirdParty thirdPartyInstance ;
private int myClassVariable ;
private void writeObject(ObjectOutputStream oos)
{
try
{
oos.defaultWriteObject();
oos.writeInt(thirdPartyInstance.getThirdPartyVariable());
oos.writeInt(thirdPartyInstance.getFourthPartyInstance().getFourthPartyVariable());
}
catch(Exception e)
{
e.printStackTrace();
}
}
private void readObject(ObjectInputStream ois)
{
try
{
ois.defaultReadObject(); //the call to defaultReadObject method must always be before any other code in the try block
//Reconstructing thirdPartyInstance
thirdPartyInstance =new ThirdParty(ois.readInt(),new FourthParty(ois.readInt()));
}
catch(Exception e)
{
e.printStackTrace();
}
}
MyClass(int myClassVariable, ThirdParty thirdPartyInstance)
{
this.myClassVariable=myClassVariable;
this.thirdPartyInstance=thirdPartyInstance;
}
ThirdParty getThirdPartyInstance()
{
return thirdPartyInstance;
}
int getMyClassVariable()
{
return myClassVariable;
}
public static void main(String args[])
{
FourthParty fourthPartyInstance=new FourthParty(45);
ThirdParty thirdPartyInstance=new ThirdParty(13,fourthPartyInstance);
MyClass myClassInstance=new MyClass(7,thirdPartyInstance);
System.out.println("Before: ThirdParty variable value is "+myClassInstance.getThirdPartyInstance().getThirdPartyVariable());
System.out.println("Before: FourthParty variable value is "+myClassInstance.getThirdPartyInstance().getFourthPartyInstance().getFourthPartyVariable());
System.out.println("Before: MyClass variable value is "+myClassInstance.getMyClassVariable());
try
{
FileOutputStream fios=new FileOutputStream("D://TestFileq.ser");
ObjectOutputStream oos=new ObjectOutputStream(fios);
oos.writeObject(myClassInstance);
oos.close();
FileInputStream fi = new FileInputStream("D://TestFileq.ser");
ObjectInputStream objectIn = new ObjectInputStream(fi);
MyClass myClassInst = (MyClass)objectIn.readObject();
System.out.println("After: ThirdParty variable value is "+myClassInst.getThirdPartyInstance().getThirdPartyVariable());
System.out.println("After: FourthParty variable value is "+myClassInst.getThirdPartyInstance().getFourthPartyInstance().getFourthPartyVariable());
System.out.println("After:MyClass variable value is "+myClassInst.getMyClassVariable());
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
class ThirdParty
{
private int thirdPartyVariable;
private FourthParty fourthPartyInstance;
ThirdParty(int thirdPartyVariable,FourthParty fourthPartyInstance)
{
this.thirdPartyVariable=thirdPartyVariable;
this.fourthPartyInstance=fourthPartyInstance;
}
int getThirdPartyVariable()
{
return thirdPartyVariable;
}
FourthParty getFourthPartyInstance()
{
return fourthPartyInstance;
}
}
class FourthParty
{
private int fourthPartyVariable;
FourthParty(int fourthPartyVariable)
{
this.fourthPartyVariable=fourthPartyVariable;
}
int getFourthPartyVariable()
{
return fourthPartyVariable;
}
}
Tenga en cuenta que la thirdPartyInstance en MiClase debe ser declarado transitoria de otro modo una excepción del tipo 'java.io.NotSerializableException' ocurre. Para obtener más información, consulte: SCJP Programador certificado para Java 6 por "Cathy Sierra", número de página 497
¿lo necesita para ser compatible con versiones futuras? –
No, no necesita ser compatible con versiones futuras. – Kyle
¿Solo quieres persistir en los datos? Si es así, ¿por qué no usar JAXB? – Boltimuss