菜單列表使用map 組裝菜單樹

環境

jdk1.8

實體

public class SysMenu implements Serializable {
    private static final long serialVersionUID = 551217284660329182428L;
    @ApiModelProperty("菜單id")
    private Long id;
    @ApiModelProperty("菜單父id")
    private Long parentId;
    @ApiModelProperty("菜單地址")
    private String url;
    @ApiModelProperty("菜單標題名稱")
    private String name;
    @ApiModelProperty("排序")
    private Integer sort;
    @ApiModelProperty("子節點（可以根據當前是否爲空來判斷是否有下級菜單(或者根據這個是否爲空來判斷當前 url是否可點擊)）")
    private List<SysMenu> children;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Long getParentId() {
        return parentId;
    }

    public void setParentId(Long parentId) {
        this.parentId = parentId;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getSort() {
        return sort;
    }

    public void setSort(Integer sort) {
        this.sort = sort;
    }

    public List<SysMenu> getChildren() {
        return children;
    }

    public void setChildren(List<SysMenu> children) {
        this.children = children;
    }
}

菜單列表轉樹

    private List<SysMenu> sysMenuTree(List<SysMenu> sysMenus) {
        List<SysMenu> nodeTrees = new ArrayList<>();
        Map<Long, SysMenu> sysMenuMap = sysMenus.stream().collect(Collectors.toMap(SysMenu::getId, sysMenu -> sysMenu));
        for (Long id : sysMenuMap.keySet()) {
            SysMenu sysMenu = sysMenuMap.get(id);
            Long parentId = sysMenu.getParentId();
            if (parentId == null || parentId == 0L || !sysMenuMap.containsKey(parentId)) {
                nodeTrees.add(sysMenu);
            } else {
                SysMenu parentTreeNode = sysMenuMap.get(parentId);
                if (parentTreeNode.getChildren() == null) {
                    parentTreeNode.setChildren(new ArrayList<>());
                }
                parentTreeNode.getChildren().add(sysMenu);
                parentTreeNode.getChildren().sort(Comparator.comparing(SysMenu::getSort));
            }
        }
        //取根節點的樹
        nodeTrees = nodeTrees.stream().filter(sysMenu -> sysMenu.getParentId() == 0L).collect(Collectors.toList());
        return nodeTrees;
    }