FIX message to JSON convertor

fix2json.java

import com.google.common.collect.ImmutableSet;
import com.google.common.reflect.ClassPath;
import com.google.gson.Gson;
import com.google.gson.JsonObject;
import quickfix.FieldNotFound;
import quickfix.Message;

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class FIX2Json {

    private static final Gson gson = new Gson();

    private Map<Integer, String> tagToNameMap;

    public FIX2Json() {
        tagToNameMap = new HashMap<>();
        tagToNameMap.putAll(getTagToNameMap("quickfix.field"));
    }

    private static Map<Integer, String> getTagToNameMap(String packageName) {
        Map<Integer, String> tagToNameMap = new HashMap<>();
        try {
            ClassPath classPath = ClassPath.from(ClassLoader.getSystemClassLoader());
            ImmutableSet<ClassPath.ClassInfo> classes = classPath.getTopLevelClasses(packageName);
            for (ClassPath.ClassInfo classInfo : classes) {
                Field field;
                try {
                    field = classInfo.load().getField("FIELD");
                } catch (NoSuchFieldException e) {
                    continue;
                }

                int fieldTag = field.getInt(null);
                String fieldName = classInfo.getSimpleName();
                tagToNameMap.put(fieldTag, fieldName);
            }
        } catch (IOException | IllegalAccessException e) {
            e.printStackTrace();
        }

        return tagToNameMap;
    }

    public String fix2Json(Message message) {
        JsonObject jsonObject = new JsonObject();

        quickfix.Message.Header header = message.getHeader();
        Iterator<quickfix.Field<?>> headerIterator = header.iterator();
        while (headerIterator.hasNext()) {
            quickfix.Field<?> field = headerIterator.next();

            String name = tagToNameMap.get(field.getTag());
            if (name == null) {
                name = String.valueOf(field.getTag());
            }
            try {
                jsonObject.addProperty(name, header.getString(field.getTag()));
            } catch (FieldNotFound fieldNotFound) {
                // ignore, should not happen
            }
        }

        Iterator<quickfix.Field<?>> bodyIterator = message.iterator();
        while (bodyIterator.hasNext()) {
            quickfix.Field<?> field = bodyIterator.next();

            String name = tagToNameMap.get(field.getTag());
            if (name == null) {
                name = String.valueOf(field.getTag());
            }
            try {
                jsonObject.addProperty(name, message.getString(field.getTag()));
            } catch (FieldNotFound fieldNotFound) {
                // ignore, should not happen
            }
        }

        jsonObject.addProperty("RawData", message.toString());

        return gson.toJson(jsonObject);
    }
}