Is it possible to define a Spring Repository for shared classes? - spring

Question

I have a class User which is shared between the server and the android client. So I don't want to annotate the class with an #id annotation.
What is the best way to deal with this in spring-jpa?

Answer 1

I believe the simplest possible way is to fallback to xml mapping so your domain objects will stay pure.
Spring-boot will notice that you're using this type of mapping and configure hibernate for you out of the box.
Here is a simple example:
package com.stackoverflow.so45264894;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.data.repository.CrudRepository;
#SpringBootApplication
#EnableJpaRepositories
public class So45264894Application {
public static void main(String[] args) {
SpringApplication.run(So45264894Application.class, args);
}
public static class User {
private Long id;
private String username;
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public String getUsername() { return username; }
public void setUsername(String username) { this.username = username; }
}
#Bean
CommandLineRunner run(UserRepository userRepository) {
final User user = new User();
user.setUsername("admin");
return args -> userRepository.save(user);
}
}
interface UserRepository extends CrudRepository<So45264894Application.User, Long> {
}
And mapping from /src/main/resources/com/stackoverflow/so45264894/User.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.stackoverflow.so45264894" default-access="field">
<class name="com.stackoverflow.so45264894.So45264894Application$User" table="users" dynamic-update="true">
<id name="id" type="java.lang.Long">
<column name="user_id" sql-type="integer"/>
<generator class="identity"/>
</id>
<property name="username" column="username" unique="true"/>
</class>
</hibernate-mapping>
Output:
Hibernate: drop table users if exists
Hibernate: create table users (user_id integer generated by default as identity, username varchar(255), primary key (user_id))
Hibernate: alter table users add constraint UK_r43af9ap4edm43mmtq01oddj6 unique (username)
Hibernate: insert into users (username, user_id) values (?, ?) // <- this is userRepository.save() call