In this EJB-JPA tutorial, we will add methods to Bean layer to add Job to the Jobs Table. The goal is to create a Job and assign it to an employee(s).
Remote Interface
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package tube.codingexamples.ejb.statelessbean; import java.util.List; import javax.ejb.Remote; import tube.coding.examples.jpa.entity.Employee; import tube.coding.examples.jpa.entity.Job; @Remote public interface EmpJobBeanRemote { //Sample 8.08: Bean Method to add Employee public Employee addEmployee(String FName, String MName, String LName, int jobLevel, int jobid); public List<Job> queryJobs(); //Sample 8.19: Bean Method for Add Job/Modify Flow public Job addJob(String jobDesc, int minExp, int maxExp); public List<Employee> queryEmployees(); public List<Employee> queryEmployees(int jobId); } |
Bean Implementation
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package tube.codingexamples.ejb.statelessbean; import java.util.List; import javax.ejb.LocalBean; import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.Query; import tube.coding.examples.jpa.entity.Employee; import tube.coding.examples.jpa.entity.Job; @Stateless(mappedName = "EmpJobBean") @LocalBean public class EmpJobBean implements EmpJobBeanRemote { //Sample 8.09: Create Entiry Manager, UnitName is from persistance.xml @PersistenceContext(unitName = "JPASavingsAccount") EntityManager em; public EmpJobBean() { } //Sample 8.10: Implement the Add Employee Method public Employee addEmployee(String FName, String MName, String LName, int jobLevel, int jobid) { //8.10.1: Create Employee Instance Employee emp = new Employee(); emp.setFirstName(FName); emp.setMidName(MName); emp.setLastName(LName); emp.setJobLevel(jobLevel); //8.10.2: Generate EmpId and Set it String id = "PMA42628M"; Integer num = (int) (Math.random() * 100000); id = id.replace("42628", num.toString()); emp.setId(id); //8.10.3: Hook the Job to Employee. EM will take care of the relation Job jobToLink = em.find(Job.class, jobid); emp.setJob(jobToLink); em.persist(emp); return emp; } //Sample 8.11: Implement query jobs public List<Job> queryJobs() { String JpaSql = "Select J from Job J "; Query query = em.createQuery(JpaSql); List<Job> jobs = (List<Job>) query.getResultList(); return jobs; } //Sample 8.20: Get all Employees @Override public List<Employee> queryEmployees() { String JpaSql = "Select E from Employee E "; Query query = em.createQuery(JpaSql); List<Employee> employees = (List<Employee>) query.getResultList(); return employees; } //Sample 8.21: Add Job to DB [with 1-Many Relation] @Override public Job addJob(String jobDesc, int minExp, int maxExp) { //8.21.1: Set Fields Job job = new Job(); job.setJobDesc(jobDesc); job.setMinExp(minExp); job.setMaxExp(maxExp); //8.21.2: 1-Many Link //job.setEmployees(null); //8.21.3: Push to DB em.persist(job); return job; } //Sample 8.22: Find Employee with Specific Job and Return @Override public List<Employee> queryEmployees(int jobId) { //8.22.1: Find Job First Job job = em.find(Job.class, jobId); //8.22.2: Return Employees. [Null should be checked by the caller] //Remember! Job is a one to many entriy return job.getEmployees(); } } |
Categories: JavaEE-EJB-Tube
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