How to convert java objects to json format
How to convert java objects to json format
Overview:
JSON (JavaScript Object Notation) is a lightweight data format for data exchange.In Java programming, we often need to convert the Java object into a JSON format for data transmission or storage on the network.
This article will introduce several commonly used methods to convert the Java object to JSON format.
Method 1: Use the jackson library
Jackson is a powerful Java library that is used to process data in JSON format.The following is an example code that uses the Jackson library to convert Java objects to JSON format:
import com.fasterxml.jackson.databind.ObjectMapper;
public class Person {
private String name;
private int age;
// omit the constructor and getter/setter method
public static void main(String[] args) throws Exception {
ObjectMapper mapper = new ObjectMapper();
Person Person = New Person ("Zhang San", 25);
// Convert the object to JSON string
String json = mapper.writeValueAsString(person);
System.out.println(json);
// Convert json string to object
Person restoredPerson = mapper.readValue(json, Person.class);
System.out.println(restoredPerson.getName());
System.out.println(restoredPerson.getAge());
}
}
Method 2: Use the GSON library
GSON is a library provided by Google to convert between Java objects and JSON data.The following is a sample code that converts Java objects into JSON format using the GSON library:
import com.google.gson.Gson;
public class Person {
private String name;
private int age;
// omit the constructor and getter/setter method
public static void main(String[] args) {
Gson gson = new Gson();
Person Person = New Person ("Zhang San", 25);
// Convert the object to JSON string
String json = gson.toJson(person);
System.out.println(json);
// Convert json string to object
Person restoredPerson = gson.fromJson(json, Person.class);
System.out.println(restoredPerson.getName());
System.out.println(restoredPerson.getAge());
}
}
Method 3: Use the json library
If you don't want to rely on the third -party library, you can use the JSON library provided by Java.Below is a sample code that uses the JSON library to convert Java objects into json format:
import org.json.JSONObject;
public class Person {
private String name;
private int age;
// omit the constructor and getter/setter method
public static void main(String[] args) {
Person Person = New Person ("Zhang San", 25);
// Convert the object to JSON string
JSONObject json = new JSONObject(person);
System.out.println(json.toString());
// Convert json string to object
Person restoredPerson = new Person(json.getString("name"), json.getInt("age"));
System.out.println(restoredPerson.getName());
System.out.println(restoredPerson.getAge());
}
}
Summarize:
This article introduces how to use Jackson, GSON, and Java's JSON libraries to convert Java objects into JSON format.You can choose a suitable method based on your needs to achieve JSON conversion.
