hieuhoang25 / mapper-object-in-spring

Getting Started

Reference Documentation

For further reference, please consider the following sections:

• Official Gradle documentation
• Spring Boot Gradle Plugin Reference Guide
• Create an OCI image
• Spring Web

Guides

The following guides illustrate how to use some features concretely:

• Building a RESTful Web Service
• Serving Web Content with Spring MVC
• Building REST services with Spring

Intelligent object mapping library

• ObjectMapper - Jackson
• ModelMapper
• MapStruct
• Orika

ObjectMapper

The ObjectMapper class is a part of the Jackson library, which is a widely used library for JSON processing. Jackson provides a set of tools for reading and writing JSON data, and the ObjectMapper class is a central component for these operations.

1. JSON Serialization(Java to JSON)

• It can convert Java object into their corresponding JSON representation
• demo

import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonSerializationDemo {
    public static void main(String[] args) throws Exception {
        // Create an instance of the Person class
        Person person = new Person();
        person.setName("John Doe");
        person.setAge(30);

        // Create an ObjectMapper
        ObjectMapper objectMapper = new ObjectMapper();

        // Serialize the Person object to JSON
        String jsonString = objectMapper.writeValueAsString(person);

        // Print the JSON string
        System.out.println("JSON String: " + jsonString);
    }
}

2. JSON Deserialization (JSON to Java)

• It can convert JSON data into Java objects
• Demo

import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonDeserializationDemo {
    public static void main(String[] args) throws Exception {
        // JSON string representing a Person
        String jsonString = "{\"name\":\"John Doe\",\"age\":30}";

        // Create an ObjectMapper
        ObjectMapper objectMapper = new ObjectMapper();

        // Deserialize the JSON string to a Person object
        Person person = objectMapper.readValue(jsonString, Person.class);

        // Access the deserialized object's properties
        System.out.println("Name: " + person.getName());
        System.out.println("Age: " + person.getAge());
    }
}

3. Object Mapping(General-purpose object mapping)

• It can be used for general-purpose object mapping, not necessarily related to JSON. You can map objects between different Java types
• Demo

import com.fasterxml.jackson.databind.ObjectMapper;

public class ObjectMappingDemo {
    public static void main(String[] args) throws Exception {
        // Create an instance of PersonDto
        PersonDto personDto = new PersonDto();
        personDto.setName("John Doe");
        personDto.setAge(30);

        // Create an ObjectMapper
        ObjectMapper objectMapper = new ObjectMapper();

        // Map PersonDto to PersonEntity
        PersonEntity personEntity = objectMapper.convertValue(personDto, PersonEntity.class);

        // Access the mapped object's properties
        System.out.println("Mapped Entity: " + personEntity.getFullName() + ", " + personEntity.getYears());

        // Map PersonEntity to PersonDto
        PersonDto mappedDto = objectMapper.convertValue(personEntity, PersonDto.class);

        // Access the reverse-mapped object's properties
        System.out.println("Mapped DTO: " + mappedDto.getName() + ", " + mappedDto.getAge());
    }
}

4. Configuration and Customization:

• ObjectMapper allows you to configure various aspects of the serialization deserialization process, such as handling of dates, customization of property naming conventions, and more.
• Demo

import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import com.fasterxml.jackson.databind.ObjectMapper;

public class ObjectMapperCustomizationDemo {
    public static void main(String[] args) throws Exception {
        ObjectMapper objectMapper = new ObjectMapper();
        
        // Set custom property naming strategy
        objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
        // Ignore unknown properties during deserialization
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        objectMapper.setDateFormat(new StdDateFormat().withColonInTimeZone(true));
        // ... other config
    }
}

5. Dependency

<dependencies>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.13.0</version> <!-- Check for the latest version -->
    </dependency>
</dependencies>

ModelMapper