JpaTest.java

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package myapp;

import javax.persistence.*;
import javax.transaction.*;
import java.io.*;

public class JpaTest {

    private EntityManagerFactory emf;
    private EntityManager em;
    private UserTransaction utx;
    PrintWriter out;
    private static Department deptRef[] = new Department[2];
    private static Employee empRef[] = new Employee[5];

    public JpaTest(){}    

    public JpaTest(EntityManagerFactory emf, EntityManager em, 
	    UserTransaction utx, PrintWriter out){
       this.emf = emf;
       this.em = em;
       this.utx = utx;
       this.out = out;
    }    

    protected boolean lazyLoadingInit(){
       boolean status = false;
       out.println("-----lazeLoadingInit()---------");
       try {        
	 deptRef[0] = new Department(1, "Engineering");
	 deptRef[1] = new Department(2, "Marketing");
	 utx.begin();
	 em.joinTransaction(); 
	 for (int i=0; i < 2; i++ ) {
	   em.persist(deptRef[i]);
	 }
	 utx.commit();

	 empRef[0] = new Employee(1, "Alan", "Frechette", deptRef[0]);
	 empRef[1] = new Employee(2, "Arthur", "Wesley", deptRef[0]);
	 empRef[2] = new Employee(3, "Abe", "White", deptRef[0]);
	 empRef[3] = new Employee(4, "Paul", "Hinz", deptRef[1]);
	 empRef[4] = new Employee(5, "Carla", "Calrson", deptRef[1]);
	 utx.begin();
	 em.joinTransaction(); 
	 for (int i=0; i<5; i++ ) {
	   em.persist(empRef[i]);
	 }
	 utx.commit();
	 status = true;
       } catch(Exception ex){
	 ex.printStackTrace();
       }
       out.println("-----status = " + status + "---------");
       return status;
    }

    public boolean lazyLoadingByFind(int employeeID) {
        
      boolean status=true;
      out.println("------------lazyLoadingAfterFind -----------");
      out.println("employeeID = "+ employeeID);
      Employee emp = em.find(Employee.class, employeeID);

      out.println("found: emp.id=" + emp.getId());        

      try {
	// 1. get Department before loading
	Department deptBL = emp.getDepartmentNoWeaving();
	out.println("1. before loading: deptBL="+deptBL);
	String deptNameBL = null;
	if (deptBL != null) {
	  deptNameBL = deptBL.getName();
	  out.println("deptNameBL="+deptNameBL);
	}
	// assert deptBL == null;
        if (deptBL != null) {
            status = false;
	}

	// 2. loading
	String deptName = emp.getDepartment().getName(); 
	out.println("2. loading, deptName = " + deptName);

	// 3. get Department after loading
	Department deptAL = emp.getDepartmentNoWeaving();
	out.println("3. after loading: deptAL="+deptAL);
	String deptNameAL = deptAL.getName();
	System.out.println("deptNameAL="+deptNameAL);
	//   assert deptAL != null
	//   assert deptAL.getName == deptName; 
        if (deptAL == null ||  deptNameAL != deptName) {
	    status = false;
	}
      } catch(Exception ex){
	status = false;
	ex.printStackTrace();
      }

      out.println("-----status = " + status + "---------");
      return status;
    }

    public boolean lazyLoadingByQuery(String fName) {
        
      boolean status=true;
      out.println("------------lazyLoadingByQuery -----------");
      out.println("fName = "+ fName);
      Query query = em.createQuery(
	"SELECT e FROM Employee e WHERE e.firstName like :firstName")
	.setParameter("firstName", fName);;
      Employee emp = (Employee) query.getSingleResult();
    
      out.println("queried: emp.firstName=" + emp.getFirstName());

      try {
	// 1. get Department before loading
	Department deptBL = emp.getDepartmentNoWeaving();
	out.println("1. before loading: deptBL="+deptBL);
	String deptNameBL = null;
	if (deptBL != null) {
	  deptNameBL = deptBL.getName();
	  out.println("deptNameBL="+deptNameBL);
	}
	// assert deptBL == null;
        if (deptBL != null) {
            status = false;
	}

	// 2. loading
	String deptName = emp.getDepartment().getName(); 
	System.out.println("2. loading, deptName = " + deptName);

	// 3. get Department after loading
	Department deptAL = emp.getDepartmentNoWeaving();
	out.println("3. after loading: deptAL="+deptAL);
	String deptNameAL = deptAL.getName();
	out.println("deptNameAL="+deptNameAL);
	//   assert deptAL != null
	//   assert deptAL.getName == deptName; 
        if (deptAL == null ||  deptNameAL != deptName) {
	    status = false;
	}
      } catch(Exception ex){
	status = false;
	ex.printStackTrace();
      }
      out.println("-----status = " + status + "---------");
      return status;
    }

}