Map数据封装_list> 封装值

1、Map封装数据库数据
@Service
public class ItemCatServiceImp implements ItemCatService{
@Autowired
private ItemCatMapper itemCatMapper;
public Map<Integer,List> getMap(){
Map<Integer,List>map=new HashMap<Integer,List>();
Listlist=itemCatMapper.selectList(null);
for (ItemCat itemCat:list){
if (map.containsKey(itemCat.getParentId())){
map.get(itemCat.getParentId()).add(itemCat);
}
else {
Listlist1=new ArrayList<>();
list1.add(itemCat);
map.put(itemCat.getParentId(), list1);
}
}
return map;
}
@Override
public List findItemCatList(Integer type) {
List itemCats=new ArrayList<>();
List itemCats1=new ArrayList<>();
//封装map集合
Map<Integer,List>map=getMap();
if (type1){
return map.get(0);
}
if (type2){
return getLevel2(map);
}
if (type==3){
return getLevel3(map);
}
return null;
}
private List getLevel2(Map<Integer,List> map){
List list=map.get(0);
for (ItemCat itemCat:list){
ListtwoList=map.get(itemCat.getId());
itemCat.setChildren(twoList);
}
return list;
}
private ListgetLevel3(Map<Integer,List> map){
Listlist= getLevel2(map);
//一级
for (ItemCat itemCat1:list){
List list2=itemCat1.getChildren();
for (ItemCat itemCat2:list2){
Listlist3=map.get(itemCat2.getId());
itemCat2.setChildren(list3);
}
itemCat1.setChildren(list2);
}
return list;
}
}