Detailed explanation of the usage of Orika, an efficient object mapping library in Java

1.What is Orika

Orika is an efficient Java object mapping library designed to simplify conversion between objects in Java applications. It maps the properties of one object to another through automated and optimized ways, reducing the need to write duplicate code manually. Orika is particularly suitable for handling complex object structures and the conversion between large data transfer objects (DTOs) and entity objects.

2. Principle

Orika's principle is mainly based on Java's reflection mechanism and bytecode generation technology to achieve efficient object mapping. Here is a brief overview of how Orika works:

Reflection mechanism:Orika uses Java's reflection mechanism to analyze the properties of the source and target objects. This allows it to dynamically determine which properties need to be mapped and how to map.

Bytecode generation: To improve performance, Orika generates bytecode at runtime to perform mapping operations. This approach is faster than traditional reflection calls, because the generated bytecode can directly manipulate the object's properties without indirect access through reflection.

MapperFactory and MapperFacade: Used by OrikaMapperFactoryto configure and create mappers.MapperFacadeIt is a core interface that provides the function of object mapping. The developer callsMapperFacadeofmapMethods to perform mapping between objects.

Automatic mapping and custom mapping:Orika supports automatic mapping, that is, it will automatically map if the attribute names and types of the source and target objects match. For more complex mapping requirements, Orika allows developers to define custom mapping logic.

Built-in converter:Orika provides some built-in converters for handling common data type conversions. These converters can be automatically applied during the mapping process, ensuring compatibility between different types.

3. Application scenarios

DTO and entity conversion: In a hierarchical architecture, it is usually necessary to convert between a data transfer object (DTO) and an entity object. Orika can automatically handle these transformations, reducing manual code writing.

Microservice architecture: In the microservice architecture, data exchange between different services requires object conversion, and Orika can complete these tasks efficiently.

Data migration: During data migration or data synchronization, data needs to be converted from one structure to another, and Orika can simplify this process.

API Integration: When integrating third-party APIs, it is often necessary to convert API responses to object structures inside the application, and Orika can help achieve this.

4. Code Example

Here is a simple Orika usage example showing how to map between two Java objects:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="/POM/4.0.0"
         xmlns:xsi="http:///2001/XMLSchema-instance"
         xsi:schemaLocation="/POM/4.0.0 /xsd/maven-4.0.">
    <parent>
        <artifactId>Java-demo</artifactId>
        <groupId></groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>Orika</artifactId>

    <properties>
        <>17</>
        <>17</>
    </properties>
    <dependencies>
        <dependency>
            <groupId></groupId>
            <artifactId>orika-core</artifactId>
            <version>1.5.4</version>
        </dependency>
        <dependency>
            <groupId></groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.11</version>
        </dependency>
    </dependencies>
</project>

OrikaExample

package ;

import ;
import ;

public class OrikaExample {
    public static void main(String[] args) {
        // Create MapperFactory
        DefaultMapperFactory mapperFactory = new ().build();

        // Get MapperFacade
        MapperFacade mapper = ();

        // Define source object
        SourceObject source = new SourceObject();
        (1);
        ("John Doe");

        // Perform mapping
        DestinationObject destination = (source, );

        // Output results
        ("Destination ID: " + ());
        ("Destination Name: " + ());
    }
}

Source

package ;

class SourceObject {
    private int id;
    private String name;

    // Getters and Setters
    public int getId() { return id; }
    public void setId(int id) {  = id; }
    public String getName() { return name; }
    public void setName(String name) {  = name; }
}

Target class

package ;

class DestinationObject {
    private int id;
    private String name;

    // Getters and Setters
    public int getId() { return id; }
    public void setId(int id) {  = id; }
    public String getName() { return name; }
    public void setName(String name) {  = name; }
}

In this example,SourceObjectandDestinationObjectare two classes with the same properties. Orika byMapperFacadeAutomaticallySourceObjectMap attributes toDestinationObjectmiddle.

The above are just some key codes. Please refer to the code repository below.

Code Repository

/Harries/Java-demo(Orika)

5. jdk17 may encounter problems

Orika library attempts to accessofclone()Method, but due to the limitations of the module system, it is inaccessible.

Solution:

You can open the JVM option when running Java programsAccess to modules:

--add-opens /=ALL-UNNAMED

If you are using an IDE (such as IntelliJ IDEA or Eclipse), you can add the above JVM options in the run configuration.

6. Summary

Orika is a powerful and efficient Java object mapping library suitable for a variety of application scenarios, such as DTO and entity transformation, data exchange in microservice architecture, data migration and API integration. Through automated and optimized mapping capabilities, Orika helps developers reduce manual code writing and improve code maintainability and readability.

The above is a detailed explanation of the usage of Orika, an efficient object mapping library in Java. For more information about the Java Orika object mapping library, please pay attention to my other related articles!