Java Play framework using JPA as ORM. This is very simple tutorial how to develop RESTful play framework version 2.4.x, which has used activator.

1. RESTful Java Play Framework
Simple JPA CRUD

2. Prerequisite
Play Framework 2.4.x
Download here
Setup the play framework (installing)
JDK 1.8 (or later)
IntelliJ CE

3. Create New Project
Through Command Line type: activator new

4. Create New Project
Open IntelliJ and import the new project

5. Create New Project
choose import project
from external: SBT
And next just let the
default value, click
finish

6. Create New Project
Here is the
structure of Play
framework

7. The Objective
Create RESTful with Java Play Framework
Build basic API: GET, POST, PUT, DELETE
Build parameterize API
Use ORM (Object Relational Mapping) : JPA
(Java Persistence Api)

8. Configuration
build.sbt (root)
name := """Java-Play-RESTful-JPA"""
version := "1.0-SNAPSHOT"
lazy val root = (project in file(".")).enablePlugins(PlayJava)
scalaVersion := "2.11.6"
libraryDependencies ++= Seq(
javaJdbc,
cache,
javaWs,
javaJpa,
"org.hibernate" % "hibernate-entitymanager" % "3.6.9.Final”
)
routesGenerator := InjectedRoutesGenerator

9. Configuration
conf/application.conf, add:
db.default.driver=org.h2.Driver
db.default.url="jdbc:h2:mem:play"
db.default.jndiName=DefaultDS
jpa.default=defaultPersistenceUnit
For simple purpose (development), we use mem
as database on memory.

10. Configuration
Create persistence.xml at conf/META-INF
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="defaultPersistenceUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<non-jta-data-source>DefaultDS</non-jta-data-source>
<properties>
<property name="hibernate.dialect"
value="org.hibernate.dialect.H2Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
</persistence>

11. Create Simple POST
At conf/routes, we add url for API access.
POST /person controllers.Application.addperson()
The method is POST, the access to this API is
{baseurl}/person. For this example, we use json
format for body.
The process is on controllers/Application.java
method addperson()

12. Create models
Create models/Person.java
package models;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
@Entity
public class Person {
@Id
@GeneratedValue
public long id;
public String name;
}

13. Create controller
Add the method addPerson() at controller
application.java
@Transactional
@BodyParser.Of(BodyParser.Json.class)
public Result addPerson(){
JsonNode json = request().body().asJson();
Person person = Json.fromJson(json, Person.class);
if (person.toString().equals("")){
return badRequest("Missing parameter");
}
JPA.em().persist(person);
return ok();
}

14. Let’s try
First create run configuration: Choose SBT Task
and chose for the Task is run.
Execute Run.
Let curl from command line:
curl -X POST -H "Content-Type: application/json" -H "Cache-Control:
no-cache" -d '{
"name":"Faren"
}' 'http://localhost:9000/person'
It will store one object Person.

15. Create Simple GET
Add url on routes
GET /person controllers.Application.listPerson()
Add controller Application.java
@Transactional(readOnly = true)
public Result listPerson(){
CriteriaBuilder cb = JPA.em().getCriteriaBuilder();
CriteriaQuery<Person> cq = cb.createQuery(Person.class);
Root<Person> root = cq.from(Person.class);
CriteriaQuery<Person> all = cq.select(root);
TypedQuery<Person> allQuery = JPA.em().createQuery(all);
JsonNode jsonNode = toJson(allQuery.getResultList());
return ok(jsonNode);
}

16. Let’s try
No need to Rerun the server. Just curl the GET
method from command line.
curl -X GET -H "Cache-Control: no-cache" 'http://localhost:9000/person’
The Output:
[{"id":1,"name":"Faren"},{"id":2,"name":"Dromdev"},{"id":3,"name":"inidevel
oper"}]

17. Get single record
Add url on routes
GET /person/:id controllers.Application.getPerson(id: Long)
Add controller Application.java
@Transactional
public Result getPerson(Long id){
Person person = JPA.em().find(Person.class, id);
if (person==null){
return notFound("User not found");
}
return ok(toJson(person));
}

18. Let’s try
Run curl on command line:
curl -X GET -H "Cache-Control: no-cache" 'http://localhost:9000/person/1’
The Output:
{
"id": 1,
"name": "Faren"
}

19. PUT
Add url on routes
PUT /person/:id controllers.Application.updatePerson(id: Long)
Add controller Application.java
@Transactional
public Result updatePerson(Long id){
Person person = JPA.em().find(Person.class, id);
if (person==null){
return notFound("User not found");
}
JsonNode json= request().body().asJson();
Person personToBe = Json.fromJson(json, Person.class);
person.name = personToBe.name;
return ok();
}

20. DELETE
Add url on routes
DELETE /person/:id controllers.Application.deletePerson(id: Long)
Add controller Application.java
@Transactional
public Result deletePerson(Long id){
Person person = JPA.em().find(Person.class, id);
if (person==null){
return notFound("User not found");
}
JPA.em().remove(person);
return ok();
}

21. API with parameter
For example:
http://localhost:9000/searchperson?name=inideveloper
Add url on routes
GET /searchperson controllers.Application.searchPerson(name: String)
Add controller Application.java
@Transactional
public Result searchPerson(String name){
TypedQuery<Person> query = JPA.em().createQuery
("select p from Person p where p.name = :name", Person.class)
.setParameter("name", name);
try {
Person person = query.getSingleResult();
return ok(toJson(person));
}catch (NoResultException e){
return notFound("User not found");
}
}

22. Full Source Code:
https://github.com/faren/java-play-jpa