Shulou(Shulou.com)06/01 Report--

In this issue, the editor will bring you about the definition of attribute serialization and alphabetical sorting in the JSON framework Jackson. The article is rich in content and analyzes and describes for you from a professional point of view. I hope you can get something after reading this article.

Jackson is the default JSON data processing framework for Spring Boot, but it does not depend on any Spring libraries. Some partners think that Jackson can only be used within the framework of Spring, but in fact, it is not, there is no such restriction. It provides a lot of JSON data processing methods and annotations, as well as streaming API, tree model, data binding, and complex data type conversion.

1. @ JsonPropertyOrder attribute sort

Specify the property serialization order of individual member variables in the java POJO through the JsonPropertyOrder annotation.

[@ Data] (https://my.oschina.net/difrik)@JsonPropertyOrder({"salary","name","age","hobbies","friends"})public class PlayerStar {private String name; private Integer age; private String [] hobbies; / / hobby, array private List friends; / / friend private Map salary; / / annual income Map}

The final Java POJO object is serialized into the following string, and the attributes are serialized in the order defined by the JsonPropertyOrder annotation ("salary", "name", "age", "hobbies", "friends"). If you do not specify the order using JsonPropertyOrder, the default is to serialize in the order in which the member variables of the Java class are declared.

{"salary": {"2000": 10000000, "2010": 62000000, "2020": 112400000}, "name": "Jordan", "age": 45, "hobbies": ["golf", "baseball"], "friends": ["kobe", "curry", "james"]}

You can serialize the PlayerStar object into a string using the following code

/ / getInstance is an initialization method for assigning values to the attributes of PlayerStar. You can refer to Section 1 of this series: basic data preparation PlayerStar jordan = PlayerStar.getInstance (); / / ObjectMapper exists ObjectMapper mapper = new ObjectMapper () as the API utility class of Jackson; String jsonInString2 = mapper.writerWithDefaultPrettyPrinter (). WriteValueAsString (jordan); System.out.println (jsonInString2); 2. Alphabet order

Use @ JsonPropertyOrder (alphabetic = true) to define the serialization order of Java class member variables

@ JsonPropertyOrder (alphabetic = true) public class PlayerStar {/ / member variable definition is consistent with the above}

In the English alphabet, age (beginning with a) > friends (starting with f)-> hobbies (starting with h), and so on, so the final JSON serialization result is as follows:

{"age": 45, "friends": ["kobe", "curry", "james"], "hobbies": ["golf", "baseball"], "name": "Jordan", "salary": {"2000": 10000000, "2010": 62000000 "2020": 112400000}} this is the meaning of attribute serialization customization and alphabetical sorting in the JSON framework Jackson shared by the editor. If you happen to have similar doubts, you might as well refer to the above analysis to understand. If you want to know more about it, you are welcome to follow the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.