Thực hành EJB (Enterprise Java Bean) Lab 12

IT Research Department @BKAP 2015 Page 1 / 20 Lab 12 Concurrency, Listeners and Caching Mục tiêu - Optimistic locking dùng version attribute - Tạo Web Client để test Concurrent truy

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IT Research Department @BKAP 2015 Page 1 / 20

Lab 12

Concurrency, Listeners and Caching

Mục tiêu

- Optimistic locking dùng version attribute

- Tạo Web Client để test Concurrent truy cập vào Entity Class

Phần I Bài tập step by step

Bài 8.1 Xây dựng ứng dụng tích điểm thưởng cho khách hàng

Step 1: Tạo table Customer trong Database ConcurrencyDB

Step 2: Tạo JDBC ConnectionPool ConcurrencyPool và JDBC Resources jdbc/Concurrency

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Step 3: Tạo ứng dụng Enterprise ConcurrencyApp

Step 4: Tạo Entity Class Customer.java từ JDBC Resources jdbc/Concurrency

 ConcurrencyApp-ejb  Source Packages  Persistence  Entity Class (Package: entity)

 Customer.java

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package entity;

import java.io.Serializable;

import javax.persistence.Basic;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.NamedQueries;

import javax.persistence.NamedQuery;

import javax.persistence.Table;

import javax.persistence.Version;

import javax.xml.bind.annotation.XmlRootElement;

/**

*

* @author Quang

*/

@Entity

@Table(name = "Customer")

@XmlRootElement

@NamedQueries({

@NamedQuery(name = "Customer.findAll", query = "SELECT c FROM Customer c"),

@NamedQuery(name = "Customer.findById", query = "SELECT c FROM Customer c WHERE c.id = :customerId"), @NamedQuery(name = "customer.findByCustomerName", query = "SELECT c FROM Customer c WHERE

c.customerName like :customerName"),

@NamedQuery(name = "customer.findByRewardPts", query = "SELECT c FROM Customer c WHERE c.rewardPts = :rewardPts")

})

public class Customer implements Serializable {

private static final long serialVersionUID = 1L;

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

@Basic(optional = false)

@Column(name = "CustomerId")

private Long id;

@Column(name = "CustomerName")

private String customerName;

@Column(name = "RewardPts")

private int rewardPts;

@Version

private Long vesion;

public Long getId() {

return id;

}

public void setId(Long id) {

this.id = id;

}

public String getCustomerName() {

return customerName;

}

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public void setCustomerName(String customerName) {

this.customerName = customerName;

}

public int getRewardPts() {

return rewardPts;

}

public void setRewardPts(int rewardPts) {

this.rewardPts = rewardPts;

}

public Long getVesion() {

return vesion;

}

public void setVesion(Long vesion) {

this.vesion = vesion;

}

@Override

public int hashCode() {

int hash = 0;

hash += (id != null ? id.hashCode() : 0);

return hash;

}

@Override

public boolean equals(Object object) {

// TODO: Warning - this method won't work in the case the id fields are not set

if (!(object instanceof Customer)) {

return false;

}

Customer other = (Customer) object;

if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {

return false;

}

return true;

}

@Override

public String toString() {

return "entity.Customer[ id=" + id + " ]";

}

Step 5: Tạo Stateless Session Bean với Local Interface tên là RewardPtsModify

 ConcurrencyApp-ejb  Source Packages  new  Other  Enterprise JavaBeans  Session Bean

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 RewardPtsModifyLocal.java

package beanpack;

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import entity.Customer;

import javax.ejb.Local;

/**

*

* @author Quang

*/

@Local

public interface RewardPtsModifyLocal {

public void multiplyPts(Customer customer, int modifier);

public void addPts(Customer customer, int modifier);

public void addCustomer(String customerName, int startPoints);

public void rapidMultiply(Customer customer, int times) throws Exception;

public void rapidAdd(Customer customer, int times) throws Exception;

public Customer getCustomer(String customerName);

public void resetPoints(Customer customer);

public void setLocking(boolean lockingEnable);

}

 RewardPtsModify.java

package beanpack;

import entity.Customer_;

import javax.ejb.Stateless;

import javax.ejb.TransactionManagement;

import javax.ejb.TransactionManagementType;

import javax.persistence.EntityManager;

import javax.persistence.LockModeType;

import javax.persistence.PersistenceContext;

import javax.persistence.TypedQuery;

import javax.persistence.criteria.CriteriaBuilder;

import javax.persistence.criteria.CriteriaQuery;

import javax.persistence.criteria.Predicate;

import javax.persistence.criteria.Root;

/**

*

* @author Quang

*/

@Stateless

@TransactionManagement(TransactionManagementType.CONTAINER)

public class RewardPtsModify implements RewardPtsModifyLocal {

@PersistenceContext(unitName = "ConcurrencyApp-ejbPU")

EntityManager em;

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private boolean lockingEnable;

@Override

public void multiplyPts(Customer customer, int modifier) {

customer.setRewardPts(customer.getRewardPts() * modifier);

}

@Override

public void addPts(Customer customer, int modifier) {

customer.setRewardPts(customer.getRewardPts() + modifier);

}

@Override

public void addCustomer(String customerName, int startPoints) {

Customer customer = new Customer();

customer.setCustomerName(customerName);

customer.setRewardPts(startPoints);

em.persist(customer);

}

@Override

public void rapidMultiply(Customer customer, int times) throws Exception {

//Get a managable entity reference

customer = em.getReference(Customer.class, customer.getId());

//If locking is set as enabled, set an OPTIMISTIC Lock

if (lockingEnable) {

em.lock(customer, LockModeType.OPTIMISTIC);

}

//Repeatedely multiply the point with the modifier of 2

for (int i = 0; i < times; i++) {

multiplyPts(customer, 2);

Thread.sleep(2000);

}

if lockingEnable) {

em.lock(customer, LockModeType.NONE);

}

@Override

public void rapidAdd(Customer customer, int times) throws Exception {

//Get a managable entity reference

//If locking is set as enabled, set an OPTIMISTIC Lock

if (lockingEnable) {

em.lock(customer, LockModeType.OPTIMISTIC);

}

//Repeatedely increment the points with the modifier of 1

for (int i = 0; i < times; i++) {

addPts(customer, 1);

Thread.sleep(2000);

}

if lockingEnable) {

em.lock(customer, LockModeType.NONE);

}

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@Override

public Customer getCustomer(String customerName) {

Predicate cond = null;

CriteriaBuilder cb = em.getCriteriaBuilder();

CriteriaQuery<Customer> cq = cb.createQuery(Customer.class);

Root<Customer> cust = cq.from(Customer.class);

cond = cb.like(cust.get(Customer_.customerName), "%" + customerName + "%");

cq.select(cust);

cq.where(cond);

TypedQuery<Customer> query = em.createQuery(cq);

return query.getResultList().get(0);

}

@Override

public void resetPoints(Customer customer) {

//Reset the points

customer.setRewardPts(1);

}

@Override

public void setLocking(boolean lockingEnable) {

this.lockingEnable = lockingEnable;

}

Step 6: Tạo các trang jsp ở ConcurrencyApp-war

 ConcurrencyApp-war  New  Other  Web  JSP

 CustomerForm.jsp

<%@ pagecontentType="text/html" pageEncoding="UTF-8"%>

<!DOCTYPE html>

<html>

<head>

<metahttp-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Customer Form</title>

</head>

<body>

<h3>Customer Form</h3>

<divid="error" style="color: red"></div>

<formname="CustForm" method="POST" action="CustomerServlet">

<tablecolspan="2">

<tr><td>Customer Name:</td><td><inputtype="text" name="customerName"/></td></tr>

<tr><td>Reward Points:</td><td><inputtype="text" name="rewardPts"/></td></tr>

</table>

</form>

</body>

</html>

 CustomerInfo.jsp

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<!DOCTYPE html>

<html>

<head>

<title>Customer Search Page</title>

</head>

<body>

<formname="CustSearchForm" method="POST" action="CustomerSearchServlet">

<tablecolspan="2" width="60%">

<tr>

<td>Customer Name: </td>

</tr>

<tr>

<tdcolspan="2" align="center"><inputtype="submit" value="Search"/></td>

</tr>

</table>

</form>

</body>

</html>

 CustomerReward.jsp

<!DOCTYPE html>

<html>

<head>

<title>Customer Search</title>

</head>

<body>

<h3>Increment Reward Points</h3>

<formname="CustSearchForm" method="POST" action="CustomerReward">

<tablecolspan="2">

<tr>

<td>Customer Name:</td>

</tr>

<tr>

<td>Locking Enable:</td>

<td>

<selectname="locking">

<optionvalue="Yes">Yes</option>

<optionvalue="No">No</option>

</select>

</td>

</tr>

<tr>

<td>Add Times:</td>

</tr>

<tr>

<td>Multiply Times:</td>

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</tr>

<tr>

<tdcolspan="2" align="center"><inputtype="submit" value="Search"></td>

</tr>

</table>

</form>

</body>

</html>

 CustomerReset.jsp

<!DOCTYPE html>

<html>

<head>

<title>Customer Search</title>

</head>

<body>

<h3>Customer Search</h3>

<formname="CustSearchForm" method="POST" action="CustomerReset">

<tablecolspan="2">

<tr>

<td>Customer Name:</td>

</tr>

<tr>

<tdcolspan="2" align="center"><inputtype="submit" value="Reset"/></td>

</tr>

</table>

</form>

</body>

</html>

Step 7: Tạo các Servlet

 ConcurrencyApp-war  Source Paclages  New  Other  Web  Servlet (package servlet)

 CustomerInfo.java

package servlet;

import beanpack.RewardPtsModifyLocal;

import java.io.IOException;

import java.io.PrintWriter;

import javax.ejb.EJB;

import javax.servlet.ServletException;

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import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

/**

*

* @author Quang

*/

public class CustomerInfo extends HttpServlet {

@EJB

private RewardPtsModifyLocal rewardPtsModify;

/**

* Processes requests for both HTTP <code>GET</code> and <code>POST</code>

* methods

*

* @param request servlet request

* @param response servlet response

* @throws ServletException if a servlet-specific error occurs

* @throws IOException if an I/O error occurs

*/

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html;charset=UTF-8");

String customerName = request.getParameter("customerName");

try (PrintWriter out = response.getWriter()) {

/* TODO output your page here You may use following sample code */

out.println("<!DOCTYPE html>");

out.println("<html>");

out.println("<head>");

out.println("<title>Servlet CustomerInfo</title>");

out.println("</head>");

out.println("<body>");

out.println("<table><tr><th>Customer Name</th><th>Reward Points</th></tr>");

out.println("<tr><td>" + customer.getCustomerName() + "</td><td>" + customer.getRewardPts() +

"</td></tr>");

out.println("</body>");

out.println("</html>");

}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods Click on the + sign on the left to edit the code.">

/**

* Handles the HTTP <code>GET</code> method

*

* @param request servlet request

* @param response servlet response

* @throws ServletException if a servlet-specific error occurs

* @throws IOException if an I/O error occurs

*/

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

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