JsonPath 解析 json demo

gistfile1.txt

```
[
    {
        "category": "tag_foo", 
        "tagPrice": [
            {
                "activeTagDictId": 370, 
                "activePrice": 39
            }, 
            {
                "activeTagDictId": 371, 
                "activePrice": 68
            }, 
            {
                "activeTagDictId": 372, 
                "activePrice": 99
            }
        ]
    }
]
```
//解析json 得到activeTagDictId列表
List<String> idList = JsonPath.read(json, "$..activeTagDictId");
System.out.println(idList); // [370,371,372]

//解析json 得到某一activeTagDictId对应的价格
List<String> priceList = JsonPath.read(json, "$..tagPrice[?(@.activeTagDictId==371)].activePrice");
System.out.println(priceList); //[68]	

--- 
//java8 解析json得到某一属性列表 对比
List<JSONObject> joList = JSON.parseArray(json, JSONObject.class);
List<Long> list = joList.stream().flatMap(o -> o.getJSONArray("tagPrice").stream())
				.map(o -> ((JSONObject) o).getLong("activeTagDictId")).collect(toList());
System.out.println(list); // [370, 371, 372]

--
使用jq实现上述功能
➜  ~  cat test.json | jq '.[].tagPrice[].activeTagDictId'                   
370
371
372
373
374
➜  ~  cat test.json | jq '.[].tagPrice[]|select(.activeTagDictId==373)|.activePrice'
129

参考文档
https://stedolan.github.io/jq/manual/#TypesandValues