若依框架学习之获取菜单下拉树

思路

• 获取完整菜单列表，构建下拉树
• 构建前端下拉树列表：
  1. 构建树结构，如果是顶级节点，遍历该父节点的所有子节点
  2. 递归获取子节点列表

代码

controller层

 /**
     * 获取菜单下拉树列表
     */
    @GetMapping("/treeselect")
    public AjaxResult treeselect(SysMenu menu) {
        LoginUser loginUser = tokenService.getLoginUser(ServletUtils.getRequest());
        Long userId = loginUser.getUser().getUserId();
        List<SysMenu> menus = menuService.selectMenuList(menu, userId);
        return AjaxResult.success(menuService.buildMenuTreeSelect(menus));
    }

service层

    /**
     * 构建前端所需下拉树列表
     *
     * @param menus
     * @return
     */
    @Override
    public List<TreeSelect> buildMenuTreeSelect(List<SysMenu> menus) {
        List<SysMenu> menuTrees=buildMenuTree(menus);
        return menuTrees.stream().map(TreeSelect::new).collect((Collectors.toList()));
    }

    /**
     * 构建前端所需要树结构
     *
     * @param menus 菜单列表
     * @return 树结构列表
     */
    @Override
    public List<SysMenu> buildMenuTree(List<SysMenu> menus) {
        List<SysMenu> returnList = new ArrayList<SysMenu>();
        List<Long> tempList = new ArrayList<Long>();
        for (SysMenu dept : menus) {
            tempList.add(dept.getMenuId());
        }
        for (Iterator<SysMenu> iterator = menus.iterator(); iterator.hasNext(); ) {
            SysMenu menu = (SysMenu) iterator.next();
            // 如果是顶级节点, 遍历该父节点的所有子节点
            if (!tempList.contains(menu.getParentId())) {
                recursionFn(menus, menu);
                returnList.add(menu);
            }
        }
        if (returnList.isEmpty()) {
            returnList = menus;
        }
        return returnList;
    }

    /**
     * 递归列表
     *
     * @param list
     * @param t
     */
    private void recursionFn(List<SysMenu> list, SysMenu t) {
        // 得到子节点列表
        List<SysMenu> childList = getChildList(list, t);
        t.setChildren(childList);
        for (SysMenu tChild : childList) {
            if (hasChild(list, tChild)) {
                recursionFn(list, tChild);
            }
        }
    }
    /**
     * 得到子节点列表
     */
    private List<SysMenu> getChildList(List<SysMenu> list, SysMenu t) {
        List<SysMenu> tlist = new ArrayList<SysMenu>();
        Iterator<SysMenu> it = list.iterator();
        while (it.hasNext()) {
            SysMenu n = (SysMenu) it.next();
            if (n.getParentId().longValue() == t.getMenuId().longValue()) {
                tlist.add(n);
            }
        }
        return tlist;
    }

    /**
     * 判断是否有子节点
     */
    private boolean hasChild(List<SysMenu> list, SysMenu t) {
        return getChildList(list, t).size() > 0 ? true : false;
    }

treeselect

public class TreeSelect implements Serializable
{
    private static final long serialVersionUID = 1L;

    /** 节点ID */
    private Long id;

    /** 节点名称 */
    private String label;

    /** 子节点 */
    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private List<TreeSelect> children;

    public TreeSelect()
    {

    }

    public TreeSelect(SysMenu menu)
    {
        this.id = menu.getMenuId();
        this.label = menu.getMenuName();
        this.children = menu.getChildren().stream().map(TreeSelect::new).collect(Collectors.toList());
    }

    public Long getId()
    {
        return id;
    }

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

    public String getLabel()
    {
        return label;
    }

    public void setLabel(String label)
    {
        this.label = label;
    }

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

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