Understand the serialization and deserialization technology of JSON arrays in Java.

Understand the serialization and deserialization technology of JSON arrays in Java

In today's software development, data transmission and storage is a very common requirement. JSON (JavaScript Object Notation), as a lightweight data exchange format, is widely used in various programming languages. In Java, we often need to serialize and deserialize JSON for use in network transmission or storage. For arrays in JSON, Java provides some convenient techniques for operations.

In Java, there are many libraries that can be used for JSON serialization and deserialization. This article will take the commonly used Jackson library as an example to introduce how to serialize and deserialize JSON arrays.

1. Serialization of JSON array

During the serialization process, we convert the Java object into a string in JSON format. For serialization of JSON array, we need to convert Java array or collection object to JSON format array.

First, we need to introduce dependencies on the Jackson library. You can use maven to manage dependencies:

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.12.4</version>
</dependency>

Next, we define a Java class to represent a Person object:

public class Person {
    private String name;
    private int age;

    // getter and setter methods
}

Then, we create an array containing Person objects and use the ObjectMapper class to convert it into a string in JSON format:

import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.Arrays;

public class JsonArraySerializationExample {
    public static void main(String[] args) throws Exception {
        Person person1 = new Person();
        person1.setName("Alice");
        person1.setAge(25);

        Person person2 = new Person();
        person2.setName("Bob");
        person2.setAge(30);

        Person[] persons = {person1, person2};

        ObjectMapper objectMapper = new ObjectMapper();
        String json = objectMapper.writeValueAsString(persons);

        System.out.println(json);
    }
}

Run the above code and the output is as follows:

[{"name":"Alice","age":25},{"name":"Bob","age":30}]

You can see At this point, we successfully converted the array of Person objects into a JSON-formatted string.

2. Deserialization of JSON array

During the deserialization process, we convert the JSON-formatted string into a Java object. For deserialization of JSON array, we convert JSON array to Java array or collection object.

We use the above Person class as an example and create a JSON-formatted string containing the Person object. Then use the ObjectMapper class to convert it into an array of Person objects:

import com.fasterxml.jackson.databind.ObjectMapper;

import java.util.Arrays;

public class JsonArrayDeserializationExample {
    public static void main(String[] args) throws Exception {
        String json = "[{"name":"Alice","age":25},{"name":"Bob","age":30}]";

        ObjectMapper objectMapper = new ObjectMapper();
        Person[] persons = objectMapper.readValue(json, Person[].class);

        for (Person person : persons) {
            System.out.println(person.getName() + ", " + person.getAge());
        }
    }
}

Run the above code, the output is as follows:

Alice, 25
Bob, 30

As you can see, we successfully converted the JSON formatted string into Array of Person objects.

Summary

This article introduces the serialization and deserialization technology of JSON arrays in Java. By using the Jackson library, we can easily convert an array of Java objects into a JSON-formatted string for use in network transmission or storage. At the same time, we can also convert JSON format strings into Java object arrays to facilitate subsequent data operations. I hope this article will help you understand the serialization and deserialization technology of JSON arrays in Java.

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