package elte.java2_utikalauz5.io;

import java.io.*;

/**
Objektumok szerializációja.

@link.forrásfájl {@docRoot}/../data/io/src ExterTeszter.java
@link.letöltés {@docRoot}/../data/io ExterTeszter.jar
@since Java 2 Útikalauz programozóknak 1.3
*/
public class ExterTeszter {

    static class Datum implements Serializable {
      int év, hónap, nap;

    /** Verziószám */
    private final static long serialVersionUID = 15L;

      private static final ObjectStreamField[] serialPersistentFields =
                        { new ObjectStreamField("dátum", int.class) };

      private void writeObject( ObjectOutputStream out ) throws IOException {
        ObjectOutputStream.PutField adatok = out.putFields();
        adatok.put("dátum",10000*év+100*hónap+nap);
        out.writeFields();
      }

      private void readObject( ObjectInputStream in ) throws IOException,
                                                  ClassNotFoundException {
        ObjectInputStream.GetField adatok = in.readFields();
        int dátum = adatok.get("dátum",0);
        nap   = (int) (dátum % 100);
        hónap = (int) ((dátum / 100) % 100);
        év    = (int) (dátum / 10000);
      }

      public String toString() {
        return "Dátum: "+év+". "+hónap+". "+nap+".";
      }
    }

    static class B extends Datum {
    /** Verziószám */
    private final static long serialVersionUID = 15L;

      private void readObject( ObjectInputStream in ) throws IOException,
                                                  ClassNotFoundException {}
      private void writeObject( ObjectOutputStream out ) throws IOException {}
    }

    static class C extends Datum implements Externalizable {
    /** Verziószám */
    private final static long serialVersionUID = 15L;

      public C(){ super(); }

      public void readExternal( ObjectInput in ) throws IOException,
                                             ClassNotFoundException {}
      public void writeExternal( ObjectOutput out ) throws IOException {}
    }

  public static void main( String[] args )
  throws IOException, ClassNotFoundException {
    Datum b = new B();
    Datum c = new C();
    ObjectOutputStream out = new ObjectOutputStream(
                 new FileOutputStream("exter.dat") );
    b.év = c.év = 2000;
    b.hónap = b.nap = c.év = c.nap = 1;
    out.writeObject(b); out.writeObject(c);
    out.close();
    ObjectInputStream in = new ObjectInputStream(
               new FileInputStream("exter.dat") );
    b = (B)in.readObject(); System.out.println(b);
    c = (C)in.readObject(); System.out.println(c);
    in.close();
  }
}