In my last post about SeemoreJ I gave an account of how one might bootstrap a new web project using the seemorej–example–archetype. In this post I‘ll introduce how quick and easy it is to get a scaffolded CRUD application up and running.
I‘ll do this by stepping through the creation of the Person POJO (so pervasive in tutorials and demos), with Hibernate/JPA annotations as an example of a persistent model and – in the process we‘ll cover the default configuration of database interaction.
The model
Create a package called com.mycompany.model and add this class there.
import org.hibernate.validator.NotEmpty;
import org.hibernate.validator.Email;
import javax.persistence.*;
import java.io.Serializable;
import java.util.Date;
@Entity
public class Person implements Serializable {
private Long id;
private String firstName;
private String lastName;
private Date dateOfBirth;
private String emailAddress;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@NotEmpty
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
@NotEmpty
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Temporal(TemporalType.DATE)
public Date getDateOfBirth() {
return dateOfBirth;
}
public void setDateOfBirth(Date dateOfBirth) {
this.dateOfBirth = dateOfBirth;
}
@NotEmpty
public String getEmailAddress() {
return emailAddress;
}
public void setEmailAddress(String emailAddress) {
this.emailAddress = emailAddress;
}
}
There‘s a lot of annotation in this POJO. Some for JPA persistence and some for Hibernate Validator, which the Hibernate specific SeemoreJ package uses as the validation framework. We‘ll see shortly what these validation annotations do for us.
Persistence
Mapping
Add this line to hibernate.cfg.xml within the session-factory element.
Database connection
Now to configure the database connection. I‘m assuming you have MySQL installed and that this is what you‘re going to use. Find the following section in the POM (pom.xml) and change the values to something appropriate.
<properties>
<!-- ... -->
<hibernate.dialect>org.hibernate.dialect.MySQL5InnoDBDialect</hibernate.dialect>
<jdbc.groupId>mysql</jdbc.groupId>
<jdbc.artifactId>mysql-connector-java</jdbc.artifactId>
<jdbc.version>5.0.5</jdbc.version>
<jdbc.driverClassName>com.mysql.jdbc.Driver</jdbc.driverClassName>
<jdbc.url>jdbc:mysql://localhost/myapp?createDatabaseIfNotExist=true&amp;useUnicode=true&amp;characterEncoding=utf-8</jdbc.url>
<jdbc.username></jdbc.username>
<jdbc.password></jdbc.password>
</properties>
<!-- ... -->
CRUD Scaffold
Add the following class to the com.mycompany.app. Whilst this is a great deal more verbose than it would be in Rails, this is all you need to have CRUD functionality for a Hibernate mapped class. It certainly beats implementing each action required. My intention is replace this implementation inheritance with some sort of configuration, probably annotation. This would make the resulting controller classes more flexible and nicer to use.
import com.malethan.seemorej.hibernate.crud.CrudControllerHibernate;
import com.mycompany.model.Person;
public class PeopleController extends CrudControllerHibernate<Person, Long> {
public PeopleController() {
super(Person.class, Long.class);
}
}
Now start Jetty up using mvn jetty:run-exploded. If you‘re running it for the first time you‘ll have to wait for all the dependencies to download. Once it‘s up and running got to http://localhost:8080/people/list.html
What you‘ll see is a rudimentary, fairly ugly – if I‘m honest – CRUD application. On my To–do list is to make it more attractive and – through configuration – provide some customisation. Also, I‘d like to support one–to–many, many–to–many and many–to–one relationships.
In my next post about SeemoreJ I‘ll be talking about action filters and how they‘re implemented in SeemoreJ.
First published on Apr 30, 2009. Last updated on: Dec 30, 2009.
I'm Elwyn Malethan and this is my blog. I am an aspiring 