最近闲来无事,想起以前在开发需求的时候,遇到了返回属性菜单的需求,当时用了递归算法去实现的,但是总觉得写的不好,容易造成栈溢出。现在想想为啥不利用jdk8的新特性来实现,下面我就直接放出代码,有需要的自己参考一下:
import java.util.List;
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Menu {
private Integer id;
private String name;
private Integer parentId;
private List<Menu> childList;
public Menu(Integer id, String name, Integer parentId) {
this.id = id;
this.name = name;
this.parentId = parentId;
}
}
import com.alibaba.fastjson.JSON;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
public class Demo {
public static void main(String[] args){
List<Menu> menus = Arrays.asList(
new Menu(1,"根节点",0),
new Menu(2,"子节点1",1),
new Menu(3,"子节点1.1",2),
new Menu(4,"子节点1.2",2),
new Menu(5,"根节点1.3",2),
new Menu(6,"根节点2",1),
new Menu(7,"根节点2.1",6),
new Menu(8,"根节点2.2",6),
new Menu(9,"根节点2.2.1",7),
new Menu(10,"根节点2.2.2",7),
new Menu(11,"根节点3",1),
new Menu(12,"根节点3.1",11)
);
List<Menu> collect = menus.stream().filter(m -> m.getParentId() == 0).map(
(m) -> {
m.setChildList(getChildrens(m, menus));
return m;
}
).collect(Collectors.toList());
System.out.println("-------转json输出结果-------");
System.out.println(JSON.toJSON(collect));
}
public static List<Menu> getChildrens(Menu root, List<Menu> all) {
List<Menu> children = all.stream().filter(m -> {
return Objects.equals(m.getParentId(), root.getId());
}).map(
(m) -> {
m.setChildList(getChildrens(m, all));
return m;
}
).collect(Collectors.toList());
return children;
}
}