获取Map中指定key值进行处理方法

工作中有遇到获取map中指定key的情况，一个一个指定获取效率低不说，代码看起来乱，现整理的方法，希望给大家点思路

获取Map中指定key值进行处理封装方法

public class CollectUtil {

    public static void main(String[] args) {
        Map<String,Object> map = new HashMap<>();
        map.put("aa","11");
        map.put("premium","22");
        map.put("num","33");
        List<String> keys = Arrays.asList("aa","bb","dd");
        //System.out.println(getMapCollection(map,keys));
        System.out.println(getMapCollection(map,DemoEntity.class));

    }

    /**
     * 根据keys获取map中指定key存入新map
     * @param maps
     * @param keys
     * @return
     * @param <K>
     * @param <V>
     */
    public static <K, V> Map<K,V> getMapCollection(Map<K,V> maps, Iterable<K> keys){
        Map<K,V> filterMaps = new HashMap<>();
        if(maps != null && !maps.isEmpty() && keys != null){
            keys.forEach(key -> Optional.ofNullable(maps.get(key)).ifPresent(value -> filterMaps.put(key,value)));
        }
        return filterMaps;
    }

    /**
     * 根据clazz实体类中属性获取map中对应key，存入新map
     * @param maps
     * @param clazz
     * @return
     * @param <K>
     * @param <V>
     */
    public static <K, V> Map<K,V> getMapCollection(Map<K,V> maps, Class<?> clazz){
        Map<K,V> filterMaps = new HashMap<>();
        Field[] fields = clazz.getDeclaredFields();
        if(maps != null && !maps.isEmpty() && fields != null){
            Arrays.stream(fields).forEach(field -> {
                String key = field.getName();
                Optional.ofNullable(maps.get(key)).ifPresent(value -> filterMaps.put((K)key, (V) value));
            });
        }
        return filterMaps;
    }

    /**
     * 根据keys获取map中指定key的值存如list
     * @param map
     * @param keys
     * @return
     * @param <K>
     * @param <V>
     */
    public static <K, V> List<V> getListCollection(Map<K, V> map, Iterable<K> keys) {
        List<V> result = new ArrayList<>();
        if (map != null && !map.isEmpty() && keys != null) {
            keys.forEach(key -> Optional.ofNullable(map.get(key)).ifPresent(result::add));
        }
        return result;
    }

    public static <K, V> List<V> getOrderCollection(Map<K, V> map, Iterable<K> keys, Comparator<V> comparator) {
        Objects.requireNonNull(comparator);
        List<V> result = getListCollection(map, keys);
        Collections.sort(result, comparator);
        return result;
    }
}

@Data
public class DemoEntity {

    private int id;
    private Long premium;
    private String num;
}