权限菜单数据无限级遍历返回json结构数据，我这里整理2种方法，一种循环方式的，一种递归方式的
循环方式遍历
@Test
public void test2(){
Long time1 = System.currentTimeMillis();
Map map1 = new HashMap();
map1.put("id",1);
map1.put("pid","");
Map map2 = new HashMap();
map2.put("id",2);
map2.put("pid",1);
Map map21 = new HashMap();
map21.put("id",21);
map21.put("pid",1);
Map map3 = new HashMap();
map3.put("id",3);
map3.put("pid","");
Map map4 = new HashMap();
map4.put("id",4);
map4.put("pid",2);
Map map5 = new HashMap();
map5.put("id",5);
map5.put("pid",4);
Map map6 = new HashMap();
map6.put("id",6);
map6.put("pid",3);
Map map7 = new HashMap();
map7.put("id",7);
map7.put("pid","");
List<Map> list = new ArrayList<>();
list.add(map1);
list.add(map2);
list.add(map21);
list.add(map3);
list.add(map4);
list.add(map5);
list.add(map6);
list.add(map7);
//取得数据
List<Map> resultMap = list;
//定义一个Map集合 存储按指定顺序排列好的菜单
Map<String, List<Map<Object,Object>>> temp = new HashMap<String, List<Map<Object,Object>>>();
for (Map map : resultMap) {
//如果temp的键包含这个parentid
if(temp.containsKey(map.get("pid").toString())){
//那么把所有相同parentid的数据全部添加到该parentid键下
temp.get(map.get("pid").toString()).add(map);
}else{
//初始化temp 第一次用
List<Map<Object,Object>> lists = new ArrayList<Map<Object,Object>>();
lists.add(map);
temp.put(map.get("pid").toString(), lists);
}
}
//定义一个完整菜单列表
ArrayList<Map<Object,Object>> array = new ArrayList<Map<Object,Object>>();
for (Map hashMap : resultMap) {
//如果temp中的键与当前id一致
if(temp.containsKey(hashMap.get("id").toString())){
//说明temp是当前id菜单的子菜单
hashMap.put("children", temp.get(hashMap.get("id").toString()));
}
//遇到顶级菜单就添加进完整菜单列表
if("".equals(hashMap.get("pid"))){
array.add(hashMap);
}
}
System.out.println(JSON.toJSONString(array));
Long time2 = System.currentTimeMillis();
System.out.println(time2-time1);
}
递归方式遍历
@Test
public void test3(){
Long time1 = System.currentTimeMillis();
Map map1 = new HashMap();
map1.put("id",1);
map1.put("pid","");
Map map2 = new HashMap();
map2.put("id",2);
map2.put("pid",1);
Map map21 = new HashMap();
map21.put("id",21);
map21.put("pid",1);
Map map3 = new HashMap();
map3.put("id",3);
map3.put("pid","");
Map map4 = new HashMap();
map4.put("id",4);
map4.put("pid",2);
Map map5 = new HashMap();
map5.put("id",5);
map5.put("pid",4);
Map map6 = new HashMap();
map6.put("id",6);
map6.put("pid",3);
Map map7 = new HashMap();
map7.put("id",7);
map7.put("pid","");
List<Map> list = new ArrayList<>();
list.add(map1);
list.add(map2);
list.add(map21);
list.add(map3);
list.add(map4);
list.add(map5);
list.add(map6);
list.add(map7);
List<Map> treeMenuList = this.treeMenuList(list,"");
System.out.println(JSON.toJSONString(treeMenuList));
Long time2 = System.currentTimeMillis();
System.out.println(time2-time1);
}
public List<Map> treeMenuList(List<Map> menuList, String parentId) {
List<Map> childMenu = new ArrayList<>();
for (Map jsonMenu : menuList) {
String menuId = jsonMenu.get("id")+"";
String pid = jsonMenu.get("pid")+"";
if (parentId.equals(pid)) {
List<Map> c_node = treeMenuList(menuList, menuId);
if (c_node.size()>0){
jsonMenu.put("childNode", c_node);
}
childMenu.add(jsonMenu);
}
}
return childMenu;
}
经过测试，循环的速度更快，递归的稍慢一些
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