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Java embedded script how to quickly parse multi-layer json, I believe that many inexperienced people do not know what to do, so this paper summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

There are many open source packages about Json processing, such as json-lib, jackson, Gson, Fastjson. Gson is made by Google and powerful; Fastjson is made by Alibaba with fast performance. Which one to use, as long as you are happy.

Json parsing is generally for re-calculation, most of these open source packages provide rich interfaces for reading and parsing Json, but then how to filter, deeply calculate and expand multi-tier Json data into two-dimensional data for use by other services still requires complex hard coding, and generally requires the help of relational databases (creating temporary tables, parsing and storing them Then use SQL to calculate it twice, etc.), these steps will require developers to have a headache.

For example, to deal with such a scenario: the Json data of order information is divided into two layers: the first layer is the country and region, and the second layer is the detailed data. Now I want to find out the orders for North China in 2013.

Some of the source data are as follows:

[{"COUNTRY": "China", "AREA": "Northeast China", "ORDERS": [

{"ORDER_ID": 10252, "CUSTOMER_ID": "SUPRD", "EMPLOYEE_ID": 4,... }

{"ORDER_ID": 10318, "CUSTOMER_ID": "ISLAT", "EMPLOYEE_ID": 8,... }

[] }

{"COUNTRY": "China", "AREA": "East China", "ORDERS": [

{"ORDER_ID": 10249, "CUSTOMER_ID": "TOMSP", "EMPLOYEE_ID": 6,... }

{"ORDER_ID": 10251, "CUSTOMER_ID": "VICTE", "EMPLOYEE_ID": 3,... }

[] }

[]

Expect Json to be structured and filtered:

COUNTRY

AREA

ORDER_ID

CUSTOMER_ID

EMPLOYEE_ID

ORDER_DATE

China

North China

10402

ERNSH

eight

2013-01-02

China

North China

10403

ERNSH

four

2013-01-03

China

North China

10404

MAGAA

two

2013-01-03

China

North China

10407

OTTIK

two

2013-01-07

Part of the code for Java parsing should be written like this:

...

JSONObject jsonObject = JSONObject.fromObject (orderstr)

JSONArray jsonArray = jsonObject.getJSONArray ("COUNTRY")

...

JSONArray twos = jsonArray.getJSONArray ("ORDERS")

JSONObject two = null

List list = new ArrayList ()

For (int I = 0; I < twos.size (); iTunes +) {

Two = twos.getJSONObject (I)

Map map = new HashMap ()

...

List.add (map)

}

...

If there is an aggregator, Json parsing will be much easier. It not only encapsulates the Json class library twice and needs less code to implement the same algorithm, but also carefully designs a set of function libraries in the field of set operations to deal with all kinds of structured operations, and it is no longer necessary to install and configure third-party database software. For example, from parsing to filtering, it only takes 4 lines:

A

one

= json (file ("orders.json") .read ()

two

= A1.select (COUNTRY== "China" & & AREA.contain ("North China"))

three

= A2.news (ORDERS;COUNTRY,AREA,$ {B1.ORDERS.fname () .concat@c ()})

four

= A3.select (year (ORDER_DATE) = = 2013)

After reading the above, have you mastered how the Java embedded script can quickly parse multi-tier json? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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