思维导图

 一.Json串得转换

1、转换为对象

package com.lj.demo;

import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonDemo1 {
	public static void main(String[] args) throws Exception {
		// 一：实体类转换成Json串-》json对象
		JsonObject1 obj1 = new JsonObject1("l1", "学生管理", "closed");
		ObjectMapper om = new ObjectMapper();
		System.out.println(om.writeValueAsString(obj1));

		// 二：map集合转成json串-》json对象
		Map<String, Object> map = new HashMap<String, Object>();
		map.put("id", "11");
		map.put("text", "xues");
		map.put("state", "closed");
		System.out.println(om.writeValueAsString(map));

	}

}

运行结果

2、转换成数组 

package com.lj.demo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonDemo2 {
	//方式一：获取json数组 实体类对象转换成json ——> json数组
	public static void main(String[] args) throws Exception {
     JsonObject1 obj1=new JsonObject1("14", "about.html", "null");
     JsonObject1 obj2=new JsonObject1("15", "welcome.html", "null");
		List<JsonObject1> list=new ArrayList<>();
		list.add(obj1);
		list.add(obj2);
     ObjectMapper om=new ObjectMapper();
System.out.println(om.writeValueAsString(list));

//方式二：map集合对象转换成json数组  
Map<String, Object> map=new HashMap<String, Object>();
		map.put("id","14");
		map.put("text","about.html");
		map.put("state", null);
		Map<String, Object> map2=new HashMap<String, Object>();
		map2.put("id","15");
		map2.put("text","welcome.html");
		map2.put("state",null);
		List<Map<String, Object>> listMap=new ArrayList<>();
		listMap.add(map);
		listMap.add(map2);
		System.out.println(om.writeValueAsString(listMap));
	}
}

运行结果

 二、从数据库拿值然后显示到菜单并且具有层级关系