Java8中利用stream对map集合进行过滤的方法

//这里的代码和原先的代码相比做了修改，去掉了map进行对于Stream中包含的元素使用给定的转换函数进行转换操作

public static Map<String, Object> parseMapForFilter(Map<String, Object> map) {
 if (map == null) {
  return null;
 } else {
  map = map.entrySet().stream()
   .filter((e) -> checkValue(e.getValue()))
   .collect(Collectors.toMap(
    (e) -> (String) e.getKey(),
    (e) -> e.getValue()
   ));
 }
 return map;
 }
 
private static boolean checkValue(Object object) {

 if (object instanceof String && "".equals(object)) {
  return false;
 }

 if (null == object) {
  return false;
 }

 return true;
 }

 public static void main(String[] args) {
 Map<String,Object> params = new HashMap<>(16);

 params.put("a","");
 params.put("b",null);
 params.put("c","c");

 params = MapUtil.parseMapForFilter(params);
 System.out.println(params);
 System.out.println(MapUtil.parseMapForFilter(null));
 }

public static Map<String, Object> parseMapForFilterByOptional(Map<String, Object> map) {

 return Optional.ofNullable(map).map(
  (v) -> {
   Map params = v.entrySet().stream()
    .filter((e) -> checkValue(e.getValue()))
    .collect(Collectors.toMap(
     (e) -> (String) e.getKey(),
     (e) -> e.getValue()
    ));

   return params;
  }
 ).orElse(null);
 }

 public static void main(String[] args) {
 Map<String, Object> params = new HashMap<>(16);

 params.put("a", "");
 params.put("b", null);
 params.put("c", "c");

 params = MapUtil.parseMapForFilterByOptional(params);

 System.out.println(params);
 System.out.println(MapUtil.parseMapForFilterByOptional(null));
 }

{c=c}
null
优化checkValue方法
 private static boolean checkValueByOptional(Object object) {
 return (Boolean) Optional.ofNullable(object)
  .filter((e) -> e instanceof String && e.equals("") ? false : true)
  .orElse(false);
 }