在Java中用 . 深层访问JSON数据

Posted 2021-01-11 YancyMauno

本文介绍Java中解析JSON的一种方法，可以让我们在Java程序中也用x.x.x的形式访问JSON数据中的值。

代码大部分来源非本人，本人在源代码基础上加以修改以使正常运行。

代码：

// 将提取方法进行封装成方法 方便调用
        @SuppressWarnings("unchecked")
        public static Object getKeyJsonQuery(Map<?,?> map ,String jsonKey){
            String[] arrs = jsonKey.split("\.");
            Object obj = null;
            for(int i=0;i<arrs.length;i++){
                if(i==0) {
                    obj = handle(map, arrs[i]);
                }else{
                    if(obj instanceof Map){
                        obj = handle((Map<?, ?>) obj,arrs[i]);
                    }else if(obj instanceof List){
                        obj = handle((List<Map<?, ?>>) obj,arrs[i]);
                    }
                }
            }
            return obj;
        }
        //解析map类型的对象
        public static Object handle(Map<?,?> map,String key){
            return map.get(key);
        }
        // 解析list类型的对象
        @SuppressWarnings("unchecked")
        public static Object handle(List<Map<?,?>> listMap,String key){
            List<Map<String,Object>> listMaps = new ArrayList<>();
            List<Object> lists = new ArrayList<>();
            // 这里用到了java8的一个新特性 stream 流
           listMap.stream().filter(e->null !=e.get(key) ).forEach(e->{
                //表示既不是map 又不是list类型
                if(!(e.get(key) instanceof Map<?,?>) && !(e.get(key) instanceof List<?>) ) {
                   lists.add(e.get(key));
                }else{
                   listMaps.addAll((Collection<? extends Map<String, Object>>) e.get(key));
                }
            });
            return lists.size()>0 && !lists.isEmpty() ? lists:listMaps;
        }
    
        public static void main(String[] args) throws Exception {
               String json = "{"data":{"order":[{"money":"15","orders":[{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"2"},{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"3"}]},{"money":"16","orders":[{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"2"},{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"3"}]},{"money":"17","orders":[{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"2"},{"b1":[{"bc1":"1","bc2":"2"},{"bc1":"2","bc2":"3"}],"b2":"3"}]}],"info":{"record":[{"a1":"1","a2":"2"},{"a1":"1","a2":"2"},{"a1":"1","a2":"2"}]}},"time":{"addr":"123","num":{"a":"111","b":"222"}}}";
                Gson gson = new Gson();
                @SuppressWarnings("unchecked")
                Map<String,Object> map = gson.fromJson(json, Map.class);
                System.out.println(map.toString());
                String jsonKey = "data.order.money";
                //String jsonKey = "time.num.a";
                //String jsonKey ="data.info";
               Object obj =  getKeyJsonQuery(map,jsonKey);
               System.out.println(obj.toString());
        }
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作者：YancyMauno 
来源：CSDN 
原文：https://blog.csdn.net/ITmaotongxue/article/details/83013769?utm_source=copy 
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