从一个实例到另一个线程的非零/非空属性的另一个副本，嵌套方法/Java

Question

I'd like to find a clever way to deep copy all non-zero/non-null attributes from one instance of a class to another. If an attribute is a class, this class' attributes should be copied. Tried BeanUtils (apache/spring) but was not able to copy nested attributes.

Let's assume:

private class ClassA {
    String stringA;
    int intA;
}

private class ClassB {
    String stringB;
    int intB;
    ClassA objA;
}

private class ClassC {
    String fieldC;
    int intC;
    ClassB objB;
}

ClassC outdated, updated;
magicMethod(outdated, updated);

Let's take stringB attribute into consideration, magicMethod(...) should behave like this:

if(updated.objB != null && updated.objB.stringB != null) {
    if(outdated.objB == null)
        outdated.objB = new classB();
    outdated.objB.stringB = updated.objB.stringB;
}

Same with primitive types, let's take int:

if(updated.objB != null && updated.objB.int != 0) {
    if(outdated.objB == null)
        outdated.objB = new classB();
    outdated.objB.intB = updated.objB.intB;
}

Answer 1

Figured it out using orika mapper.

public static class DataFilter extends NullFilter<Object, Object> {
    public <S, D> boolean shouldMap(final Type<S> sourceType, final String sourceName, final S source,
            final Type<D> destType, final String destName, final D dest, final MappingContext mappingContext) {

        if (source instanceof String && ((String) source).isEmpty())
            return false;

        else if (source instanceof Integer && ((Integer) source).intValue() == 0)
            return false;

        return true;
    }
}

Then

    MapperFactory mapperFactory = new DefaultMapperFactory.Builder().mapNulls(false).build();
    mapperFactory.registerFilter(new DataFilter());
    mapperFactory.getMapperFacade().map(source, target);