import java.lang.reflect.Field;
import java.lang.reflect.Type;
import java.util.Iterator;
import java.util.Map.Entry;

import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;

public class PackagingDeserializer<PackagingResponse> implements com.google.gson.JsonDeserializer<PackagingResponse>{


	@Override
	public PackagingResponse deserialize(JsonElement arg0, Type arg1,
			JsonDeserializationContext arg2) throws JsonParseException {
		Class klass =  ((Class)arg1);
		Field[] fields = klass.getDeclaredFields();
		PackagingResponse r = null;
		try {
			r = (PackagingResponse)klass.newInstance();
		} catch (InstantiationException e3) {
			// TODO Auto-generated catch block
			e3.printStackTrace();
		} catch (IllegalAccessException e3) {
			// TODO Auto-generated catch block
			e3.printStackTrace();
		}
		JsonObject o = 	arg0.getAsJsonObject();
		parse(o, r);
		
		return r;
	}

	private void parse(JsonObject o, PackagingResponse r){
		Iterator<Entry<String, JsonElement>> i = o.entrySet().iterator();
		while(i.hasNext()){
			Entry<String, JsonElement> e = i.next();
			JsonElement el = e.getValue();
			if(el.isJsonObject())
				parse(el.getAsJsonObject(), r);
			for(Field f : r.getClass().getDeclaredFields()){
				f.setAccessible(true);
				if(f.getName().equals(e.getKey())){
					try {
						f.set(r,el.getAsString());
					} catch (IllegalArgumentException e1) {
						// TODO Auto-generated catch block
						e1.printStackTrace();
					} catch (IllegalAccessException e1) {
						// TODO Auto-generated catch block
						e1.printStackTrace();
					}
				}
			
			}
		}
	}
}

Change the generic class to whatever class you wish. JSON arrays, types etc, are not handled, you should do that. Purpose of this snippet is to deserialize only needed JSON keys with respect to the class members of your class.

Java Reflection and recursive JSON deserializer using Gson

java

Java