package com.cedarsoft.test.io;
import com.cedarsoft.UnsupportedVersionException;
import com.cedarsoft.Version;
import com.cedarsoft.VersionRange;
import com.cedarsoft.serialization.stax.AbstractStaxMateSerializer;
import com.cedarsoft.test.Money;
import org.codehaus.staxmate.out.SMOutputElement;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import java.io.IOException;
/**
* This is an extended version of money serializer.
* <p/>
* It represents the next step of the evolution of MoneySerializer.
* This is an example for a refactoring that might happen, after the serializer has been
* released (and shipped to thousands of customers creating millions of files).
* <p/>
* Therefore this serializer is able to still read the old format.
* Writing is only supported for the latest file.
*/
public class MoneySerializer2 extends AbstractStaxMateSerializer<Money> {
public MoneySerializer2() {
//This serializer supports an old version, too
super( "money", "http://www.cedarsoft.com/test/money", new VersionRange( new Version( 1, 0, 0 ), new Version( 1, 0, 1 ) ) );
}
@Override
public void serialize( SMOutputElement serializeTo, Money object ) throws IOException, XMLStreamException {
serializeTo.addAttribute( "cents", String.valueOf( object.getCents() ) );
//We use an attribute - just because it is possible...
}
@Override
public Money deserialize( XMLStreamReader deserializeFrom, Version formatVersion ) throws IOException, XMLStreamException {
//This serializer supports reading of an old format. Therefore we have to switch based on the format version.
//This might be solved using the strategy pattern. But in most of the cases the format changes only in small portions.
//So it seems easier to add just one if/else.
//If a serializer evolves further a switch to the strategy pattern might be done. A simple map holding the strategies should do it.
//The common case - current version
if ( formatVersion.equals( new Version( 1, 0, 1 ) ) ) {
int cents = Integer.parseInt( deserializeFrom.getAttributeValue( null, "cents" ) );
//We have to close the tag! Every stax based serializer has to close its tag
//getText does this automatically for us. But when only using attributes, we have to close it manually.
closeTag( deserializeFrom );
return new Money( cents );
//The old format that does not use an attribute but text instead
} else if ( formatVersion.equals( new Version( 1, 0, 0 ) ) ) {
int cents = Integer.parseInt( getText( deserializeFrom ) );
//We don't have to close the tag. The getText method does that for us
return new Money( cents );
//Whoo - something went terribly wrong
} else {
throw new UnsupportedVersionException( formatVersion, getFormatVersionRange() );
}
}
}