java递归生成树形结构菜单

一时失言乱红尘 2022-03-30 03:27 604阅读 0赞

一、mysql表，数据自行准备

CREATE TABLE `sys_menu` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `pid` bigint(20) DEFAULT NULL,
      `title` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
      `path` varchar(255) CHARACTER SET utf8 DEFAULT NULL,
      `level` int(11) DEFAULT NULL,
      `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
      `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=200 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci

二、创建对应的实体类

public class Menu implements Serializable {
    	
    	private static final long serialVersionUID = -5990021029947688358L;
    	
    	private Integer id;
    	private String title;//菜单标题
    	private String path;//路径
    	private Integer pid;//父菜单ID 一级菜单pid为null
    	private Integer level;//级别，排序用
    	
    	private List<Menu> children = new ArrayList<Menu>();
    
    	public Integer getId() {
    		return id;
    	}
    
    	public void setId(Integer id) {
    		this.id = id;
    	}
    
    	public String getTitle() {
    		return title;
    	}
    
    	public void setTitle(String title) {
    		this.title = title;
    	}
    
    	public String getPath() {
    		return path;
    	}
    
    	public void setPath(String path) {
    		this.path = path;
    	}
    
    	public Integer getPid() {
    		return pid;
    	}
    
    	public void setPid(Integer pid) {
    		this.pid = pid;
    	}
    
    	public Integer getLevel() {
    		return level;
    	}
    
    	public void setLevel(Integer level) {
    		this.level = level;
    	}
    
    	public List<Menu> getChildren() {
    		return children;
    	}
    
    	public void setChildren(List<Menu> children) {
    		this.children = children;
    	}
    }

三、递归组装树形结构函数实现

/**
             * @方法名: parseMenuTree<br>
             * @描述: 组装菜单<br>
             * @param list 数据库里面获取到的全量菜单列表
             * @return
             */
            public static List<Menu> parseMenuTree(List<Menu> list){
    	    List<Menu> result = new ArrayList<Menu>();
    		
    	    // 1、获取第一级节点
    	    for (Menu menu : list) {
    	        if(null == menu.getPid()) {
    		    result.add(menu);
    		}	
    	    }
    		
    	    // 2、递归获取子节点
    	    for (Menu parent : result) {
    		parent = recursiveTree(parent, list);
    	    }
    		
    	    return result;
    	}
    	
    	public static Menu recursiveTree(Menu parent, List<Menu> list) {
    	    for (Menu menu : list) {
    	        if(Objects.equals(parent.getId(),menu.getPid())) {
    		    menu = recursiveTree(menu, list);
    		    parent.getChildren().add(menu);
    		}
    	    }
    		    
    	    return parent;
    	}

四、从数据库获取菜单数据，调用组装菜单函数生成树形结构的数据

public static void main(String[] args) {
    		
    		List<Menu> list = new ArrayList<Menu>();
    		//TODO 这里从数据库获取全量菜单后放到list中
    		
    		//树形结构数据生成
    		List<Menu> result = parseMenuTree(list);
    		
    		System.out.println(JSONObject.toJSONString(result));
    	}