[Java Spring Data] JPA Example with unit test

domain/Course.java

package com.example.university.domain;
 
import javax.persistence.*;
 
/**
 * JPA Entity for a Course offered at the University.
 * <p>
 * Created by maryellenbowman.
 */
@Entity
@Table(name = "COURSE")
public class Course {
    @Id
    @GeneratedValue
    private Integer id;
 
    @Column
    private String name;
 
    @ManyToOne
    @JoinColumn
    private Department department;
 
    public Course(String name, Department department) {
        this.name = name;
        this.department = department;
    }
 
    protected Course() {
    }
 
    public Integer getId() {
        return id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setDepartment(Department department) {
        this.department = department;
    }
 
    @Override
    public String toString() {
        return "Course{" +
                "id=" + id + ", name='" + name + '\'' + ", department=" + department.getName() + '}';
    }
}

domain/Department.java

package com.example.university.domain;
 
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
 
/**
 * JPA Entity for a Department of study at the University.
 * <p>
 * Created by maryellenbowman
 */
@Entity
@Table(name = "Department")
public class Department {
    @Id
    @GeneratedValue
    private Integer id;
 
    @Column
    private String name;
 
    @OneToMany(mappedBy = "department", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private List<Course> courses = new ArrayList<>();
 
    public Department(String name) {
        this.name = name;
    }
 
    protected Department() {
    }
 
    public Integer getId() {
        return id;
    }
 
    public String getName() {
        return name;
    }
 
    public void addCourse(Course course) {
        courses.add(course);
    }
 
    @Override
    public String toString() {
        return "Department{" + "id=" + id + ", name='" + name + '\'' +
                ", courses=" + courses + '}';
    }
}

domain/Person.java

package com.example.university.domain;
 
import javax.persistence.Column;
import javax.persistence.Embeddable;
 
/**
 * Person encapsulates an individual's first and last name.
 * <p>
 * Created by maryellenbowman
 */
@Embeddable
public class Person {
    @Column
    private String firstName;
 
    @Column
    private String lastName;
 
    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }
 
    protected Person() {
    }
 
    public String getFirstName() {
        return firstName;
    }
 
    public String getLastName() {
        return lastName;
    }
 
    @Override
    public String toString() {
        return " firstName='" + firstName + '\'' +
                ", lastname='" + lastName + "\' ";
    }
}

domain/Student.java

package com.example.university.domain;

import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;

/**
 * JPA Entity representing a student at the University.
 * <p>
 * Created by maryellenbowman
 */
@Entity
@Table(name = "STUDENT")
public class Student {
    @Id
    @GeneratedValue
    private Integer studentId;

    @Column
    private boolean fullTime;

    @Column
    private Integer age;

    @Embedded
    private Person attendee;

    @OneToMany
    private List<Course> courses = new ArrayList<>();

    public Student(Person attendee, boolean fullTime, Integer age) {
        this.attendee = attendee;
        this.fullTime = fullTime;
        this.age = age;
        courses = new ArrayList<>();
    }

    protected Student() {
    }

    public Integer getStudentId() {
        return studentId;
    }

    public Person getAttendee() {
        return attendee;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public boolean isFullTime() {
        return fullTime;
    }

    public Integer getAge() {
        return age;
    }

    public List<Course> getCourses() {
        return courses;
    }

    @Override
    public String toString() {
        return "Student{" + "studentId=" + studentId + ", " + attendee + ", fullTime=" + fullTime +
                ", age=" + age + "}\n";
    }
}

repo/StudentRepository.java

package com.example.university.repo;

import com.example.university.domain.Student;
import org.springframework.data.repository.CrudRepository;

/**
 * DataSource Management for the Students at the University.
 *
 * Created by maryellenbowman
 */
public interface StudentRepository extends CrudRepository<Student, Integer>{

}

test:

package com.example.university;
 
import com.example.university.domain.Person;
import com.example.university.domain.Student;
import com.example.university.repo.StudentRepository;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
 
/**
 * Demonstrate Creation, Reading, Updating, and Deletion of Students with StudentRepository
 * <p>
 * Created by maryellenbowman
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class CrudRepositoryDemo {
 
 
    @Autowired
    StudentRepository studentRepository;
 
    /**
     * Exercise CrudRepository methods.
     */
    @Test
    public void simpleStudentCrudExample() {
        boolean fullTime = true;
        studentRepository.save(new Student(new Person("jane", "doe"), fullTime, 20));
        studentRepository.save(new Student(new Person("john", "doe"), fullTime, 22));
        studentRepository.save(new Student(new Person("mike", "smith"), fullTime, 18));
        studentRepository.save(new Student(new Person("ally", "kim"), !fullTime, 19));
 
        System.out.println("\n*************Original Students*************");
        studentRepository.findAll().forEach(System.out::println);
 
        //age up the students
        studentRepository.findAll().forEach(student -> {
            student.setAge(student.getAge() + 1);
            studentRepository.save(student);
        });
 
        System.out.println("\n*************Students a year older*************");
        studentRepository.findAll().forEach(System.out::println);
 
        studentRepository.deleteAll();
        System.out.println("\n*************Students removed*************");
        studentRepository.findAll().forEach(System.out::println);
 
    }
 
 
}