FastJson動態解析多層嵌套未知key json

使用過fastjson的同胞我們都知道fastjson內部的方法只支持解析單層json，比如這些數據:

jsonObject類型的：{"generalWorker":2,"skillWorker":3}
jsonarray類型的：
    [{"id":"zjqf001","projectId":"1","workType":"3"},{"id":"zjqf002","projectId":"1","workType":"3"},{"id":"zjqf003","projectId":"1","workType":"3"}]

但如果遇到這種類型的呢：

{ 
"generalWorker ":[{ "id ": "zjqf001 ", "projectId ": "1 ", "workType ": "3 "},{ "id ": "zjqf002 ", "projectId ": "1 ", "workType ": "3 "}], 

"projectMember ":[{ "displayOrdinal ":0, "gender ":0, "idCardNumber ": "123 ", "idCardType ": "身份證 "},{ "displayOrdinal ":0, "gender ":1, "idCardNumber ": "456 ", "idCardType ": "居住證 "}],

"skilledWorker ":[{ "cardNumber ": "WL ", "cardStatus ": "9 ", "empno ": "003 "},{ "cardNumber ": "ER ", "cardStatus ": "7 ", "empno ": "004 "}]
}

可能有些小夥伴會想到fastjson的這種用法：

List<Map<String, Object>> mapList = JSON.parseObject(str, new TypeReference<List<Map<String, Object>>>() {});

拋出異常：
Exception in thread "main" com.alibaba.fastjson.JSONException: exepct '[', but {, pos 1, json : {"generalWorker":[{"id":"zjqf001"...略

又或者這種方法:

new ObjectMapper().readValue（）
拋出異常：JSON deserialization throwing exception - Can not deserialize instance of java.util.ArrayList out of START_OBJECT token   

原因是需要一個包裝器去包裝，可以用pojo封裝，但是自己的需求是不知道傳過來的是什麼，所以不適合自己

劃重點

解析json 動態遍歷未知key與value，最終返回形式爲List<List<Map<String,Object>>>類型（當然，根據業務需求，你也可以得到Map<String,List<Map<String,Object>>>類型，需自己修改代碼）

重點方法：

   JSONArray jsonArray = (JSONArray)jsonObject.getJSONArray("xxx");

思路就是動態將json裏面的根節點全部取出來，然後在一個一個轉成jsonarray

代碼如下：(仔細看註釋)

public static void main(String[] args) {
    //模擬數據
        String str = "{
            \"generalWorker\":[{\"id\":\"zjqf001\",\"projectId\":\"1\",\"workType\":\"3\"},{\"id\":\"zjqf002\",\"projectId\":\"1\",\"workType\":\"3\"},{\"id\":\"zjqf003\",\"projectId\":\"1\",\"workType\":\"3\"},{\"id\":\"zjqf004\",\"projectId\":\"1\",\"workType\":\"3\"}],
            \"projectMember\":[{\"displayOrdinal\":0,\"gender\":0,\"idCardNumber\":\"123\",\"idCardType\":\"身份證\"},{\"displayOrdinal\":0,\"gender\":1,\"idCardNumber\":\"456\",\"idCardType\":\"居住證\"},{\"displayOrdinal\":0,\"gender\":0,\"idCardNumber\":\"789\",\"idCardType\":\"健康證\"}],
            \"skilledWorker\":[{\"cardNumber\":\"WL\",\"cardStatus\":\"9\",\"empno\":\"003\"},{\"cardNumber\":\"ER\",\"cardStatus\":\"7\",\"empno\":\"004\"},{\"cardNumber\":\"FG\",\"cardStatus\":\"8\",\"empno\":\"005\"}]}";
        //String str = "{\"generalWorker\":2,\"skillWorker\":3}";
        
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        JSONObject jsonObject = JSON.parseObject(str);
        
        //判讀是否符合數據格式
        if(str.indexOf("[") == -1){
            Map<String,Object> newMap = jsonObject;
            list.add(newMap);
        }else{
            //將[]內容替換成A，模擬成數據格式爲：{"generalWorker":"A","projectMember":"A","skilledWorker":"A"}
            int count = 0;
            int num = 0;
            while(count != -1 && num!=-1){
                count = str.indexOf("[",count+1);
                num = str.indexOf("]",count+1);
                if(count !=-1 && num!=-1){
                    str = str.replace(str.substring(count,num+1),"\"A\"");
                }
            }
            
            HashMap<String, Object> map = new HashMap<>();
            HashMap dataMap = JSON.parseObject(str, HashMap.class);
            //dataMap={"generalWorker":"A","projectMember":"A","skilledWorker":"A"}
            for (Object obj : dataMap.keySet()){//遍歷json的根節點
                //轉成jsonArray
                JSONArray jsonArray = (JSONArray)jsonObject.getJSONArray(obj.toString());
                map.put(obj.toString(),jsonArray);
            }
            list.add(map);
        }
        System.out.println(list);
    }

輸出結果：
[{
generalWorker=[{"workType":"3","id":"zjqf001","projectId":"1"},{"workType":"3","id":"zjqf002","projectId":"1"},{"workType":"3","id":"zjqf003","projectId":"1"},{"workType":"3","id":"zjqf004","projectId":"1"}],
projectMember=[{"idCardType":"身份證","displayOrdinal":0,"gender":0,"idCardNumber":"123"},{"idCardType":"居住證","displayOrdinal":0,"gender":1,"idCardNumber":"456"},{"idCardType":"健康證","displayOrdinal":0,"gender":0,"idCardNumber":"789"}],
skilledWorker=[{"empno":"003","cardNumber":"WL","cardStatus":"9"},{"empno":"004","cardNumber":"ER","cardStatus":"7"},{"empno":"005","cardNumber":"FG","cardStatus":"8"}]
}]

主要就是動態獲取其根節點，然後一個一個轉