JAVA遞歸生成樹形菜單

　　遞歸生成一個如圖的菜單，編寫兩個類數據模型Menu、和創建樹形的MenuTree。通過以下過程實現：

　　　　1.首先從菜單數據中獲取所有根節點。

　　　　2.為根節點建立次級子樹並拼接上。

　　　　3.遞歸為子節點建立次級子樹並接上，直至為末端節點拼接上空的“樹”。

　　首先，編寫數據模型Menu。每條菜單有自己的id、父節點parentId、菜單名稱text、菜單還擁有次級菜單children。

import java.util.List;

public class Menu {
    private String id;
    private String parentId;
    private String text;
    private String url;
    private String yxbz;
    private List<Menu> children;     
    public Menu(String id,String parentId,String text,String url,String yxbz) {
        this.id=id;
        this.parentId=parentId;
        this.text=text;
        this.url=url;
        this.yxbz=yxbz;   
    }
        /*省略get\set*/  
}

 

　　創建樹形結構的類MenuTree。方法getRootNode獲取所有根節點，方法builTree將根節點匯總創建樹形結構，buildChilTree為節點建立次級樹並拼接上當前樹，遞歸調用buildChilTree不斷為當前樹開枝散葉直至找不到新的子樹。完成遞歸，獲取樹形結構。

 

import java.util.ArrayList;
import java.util.List;

public class MenuTree {
    private List<Menu> menuList = new ArrayList<Menu>();
    public MenuTree(List<Menu> menuList) {
        this.menuList=menuList;
    }

    //建立樹形結構
    public List<Menu> builTree(){
        List<Menu> treeMenus =new  ArrayList<Menu>();
        for(Menu menuNode : getRootNode()) {
            menuNode=buildChilTree(menuNode);
            treeMenus.add(menuNode);
        }
        return treeMenus;
    }

    //遞歸，建立子樹形結構
    private Menu buildChilTree(Menu pNode){
        List<Menu> chilMenus =new  ArrayList<Menu>();
        for(Menu menuNode : menuList) {
            if(menuNode.getParentId().equals(pNode.getId())) {
                chilMenus.add(buildChilTree(menuNode));
            }
        }
        pNode.setChildren(chilMenus);
        return pNode;
    }

    //獲取根節點
    private List<Menu> getRootNode() {         
        List<Menu> rootMenuLists =new  ArrayList<Menu>();
        for(Menu menuNode : menuList) {
            if(menuNode.getParentId().equals("0")) {
                rootMenuLists.add(menuNode);
            }
        }
        return rootMenuLists;
    }
}

 

　　最后，插入一些數據試試效果。得到的json就可以生成圖一菜單了。

import java.util.ArrayList;
import java.util.List;
import com.alibaba.fastjson.JSON;

public class Hello {
    public static void main(String []args) {
        List<Menu>  menuList= new ArrayList<Menu>();
        /*插入一些數據*/
        menuList.add(new Menu("GN001D000","0","系統管理","/admin","Y"));
        menuList.add(new Menu("GN001D100","GN001D000","權限管理","/admin","Y"));
        menuList.add(new Menu("GN001D110","GN001D100","密碼修改","/admin","Y"));
        menuList.add(new Menu("GN001D120","GN001D100","新加用戶","/admin","Y"));
        menuList.add(new Menu("GN001D200","GN001D000","系統監控","/admin","Y"));
        menuList.add(new Menu("GN001D210","GN001D200","在線用戶","/admin","Y"));
        menuList.add(new Menu("GN002D000","0","訂閱區","/admin","Y"));
        menuList.add(new Menu("GN003D000","0","未知領域","/admin","Y"));
        /*讓我們創建樹*/
        MenuTree menuTree =new MenuTree(menuList);
        menuList=menuTree.builTree();
        /*轉為json看看效果*/
        String jsonOutput= JSON.toJSONString(menuList);
        System.out.println(jsonOutput);
    }
}

@luqp 本文地址：https://www.cnblogs.com/lucky-pin/p/10740037.html