Java之JSONArray按照某个字段分组

数据

 [
    {
        "id":"1",
        "site_name":[
            {
                "navi1":"微博热搜",
                "navi2":"热门微博"
            }
        ],
        "site_icon":"[https://s2.zimgs.cn/ims?kt=url&at=smstruct&key=aHR0cHM6Ly9waWMzNy5waG90b3Bob3RvLmNuLzIwMTUxMDI4LzAwMDUwMTgzMjkwMTE4MDJfYi5qcGc=&sign=yx:TKgi2RqCHVng2jHHHZXMpiaaa5w=&tv=400_400](https://s2.zimgs.cn/ims?kt=url&at=smstruct&key=aHR0cHM6Ly9waWMzNy5waG90b3Bob3RvLmNuLzIwMTUxMDI4LzAwMDUwMTgzMjkwMTE4MDJfYi5qcGc=&sign=yx:TKgi2RqCHVng2jHHHZXMpiaaa5w=&tv=400_400)",
        "site_url":"[https://weibo.com/](https://weibo.com/)",
        "site_type":"1"
    },
    {
        "id":"2",
        "site_name":[
            {
                "navi1":"虎嗅",
                "navi2":"24客卿"
            }
        ],
        "site_icon":"[https://h5.sinaimg.cn/m/weibo-lite/img/pwalogo.417d1674.svg](https://h5.sinaimg.cn/m/weibo-lite/img/pwalogo.417d1674.svg)",
        "site_url":"[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)",
        "site_type":"1"
    },
    {
        "id":"3",
        "site_name":[

        ],
        "site_icon":"[https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png](https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png)",
        "site_url":"[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)",
        "site_type":"2"
    },
    {
        "id":"4",
        "site_name":[

        ],
        "site_icon":"[https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png](https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png)",
        "site_url":"[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)",
        "site_type":"3"
    }
]

分组方法

Map<Object, List<Object>> groupBySiteType = siteArr.stream()
                .collect(Collectors.groupingBy(item -> JSON.parseObject(item.toString()).get("site_type")));

分组后

{"1": [{"site_name": [{"navi1": "微博热搜","navi2": "热门微博"}],"site_icon": "[https://s2.zimgs.cn/ims?kt=url&at=smstruct&key=aHR0cHM6Ly9waWMzNy5waG90b3Bob3RvLmNuLzIwMTUxMDI4LzAwMDUwMTgzMjkwMTE4MDJfYi5qcGc=&sign=yx:TKgi2RqCHVng2jHHHZXMpiaaa5w=&tv=400_400](https://s2.zimgs.cn/ims?kt=url&at=smstruct&key=aHR0cHM6Ly9waWMzNy5waG90b3Bob3RvLmNuLzIwMTUxMDI4LzAwMDUwMTgzMjkwMTE4MDJfYi5qcGc=&sign=yx:TKgi2RqCHVng2jHHHZXMpiaaa5w=&tv=400_400)","site_url": "[https://weibo.com/](https://weibo.com/)","site_type": "1","id": "1"},{"site_name": [{"navi1": "虎嗅","navi2": "24客卿"}],"site_icon": "[https://h5.sinaimg.cn/m/weibo-lite/img/pwalogo.417d1674.svg](https://h5.sinaimg.cn/m/weibo-lite/img/pwalogo.417d1674.svg)","site_url": "[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)","site_type": "1","id": "2"}],"2": [{"site_name": [],"site_icon": "[https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png](https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png)","site_url": "[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)","site_type": "2","id": "3"}],"3": [{"site_name": [],"site_icon": "[https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png](https://h5.sinaimg.cn/m/emoticon/icon/others/d_doge-be7f768d78.png)","site_url": "[https://m.weibo.cn/?jumpfrom=weibocom](https://m.weibo.cn/?jumpfrom=weibocom)","site_type": "3","id": "4"}]}}

为什么？

网上也找了许多的例子，但是大都是遍历或者明确知道JSONArray里面参数是什么对象类型的，对于这种不知道类型没见到有人记录怎么搞，故此记录，便于后人解惑！