Java8之list获取实体的某一字段：
List aList = bList.stream().map(BEntity::getName).collect(Collectors.toList());
获取某一字符串并转成string字符串:
List aList = bList.stream().map(b->"’"+b.get(“id”)+"’")).collect(Collectors.toList());
String aaa=String.join(",", fieldList);