Java 8 新特性

 @Override
    public List<String> getUserRoles(String username) {
　　　　//找到以ROLE_开头的，并且映射为字符串数组
        return userDetailsService.loadUserByUsername(username).getAuthorities().stream()
                .filter((GrantedAuthority a) -> a.getAuthority().startsWith("ROLE_"))
                .map((GrantedAuthority a) -> a.getAuthority().substring(5))
                .collect(Collectors.toList());
    }

2、收集为Map

Map<String, String> buMap = buList.stream().collect(Collectors.toMap(OrgHierarchy::getBuName, OrgHierarchy::getBuUniteCode, (key1, key2) -> key1));