In this JavaEE EJB-JPA Tutorial, we will create a JPAQL to query single entity. This example fetches the entity based on savings account person id.
Servlet Layer
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package tube.codingexamples.servlets; import java.io.IOException; import javax.ejb.EJB; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import tube.coding.examples.jpa.entity.SavingsAccount; import tube.codingexamples.ejb.statelessbean.SavingAcBeanRemote; @WebServlet("/QuerySavingAc") public class QuerySavingAc extends HttpServlet { //Sample 6.03: Have EJB Reference via Annotation @EJB(beanName="SavingAcBean") SavingAcBeanRemote SACBean; private static final long serialVersionUID = 1L; public QuerySavingAc() { super(); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //Sample 6.02: Get the request Parameters SavingsAccount account = null; String pid = request.getParameter("Pid"); String submit1 = request.getParameter("Submit1"); String pname = request.getParameter("Pname"); String submit2 = request.getParameter("Submit2"); String balance = request.getParameter("Balance"); String submit3 = request.getParameter("Submit3"); String BalSearchOption = request.getParameter("BalSearch"); String submit4 = request.getParameter("Submit4"); //Sample 6.06: Search By Customer Id if ( (pid != null && pid.trim().length() > 0) && (submit1 != null && submit1.trim().length() > 0) && (submit1.equalsIgnoreCase("Search") == true) ) { int personalBankingId = new Integer(pid).intValue(); account = SACBean.queryById(personalBankingId); //Sample 6.07: Delegate Display output to Query Result JSP request.setAttribute("Account", account); RequestDispatcher respJSP = request.getRequestDispatcher("QueryResultByIdorName.jsp"); respJSP.forward(request, response); } } } |
Remote Interface (Bean)
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package tube.codingexamples.ejb.statelessbean; import javax.ejb.Remote; import tube.coding.examples.jpa.entity.SavingsAccount; @Remote public interface SavingAcBeanRemote { //Sample 3.7: Declare the interface method public int newAccount(String accountHolderName, int initialBalance); //Sample 4.00a: Add Methods for Deposit, Withdraw and Account Closure public int depositMoney(int PersonalBankingId, int amount); public int withdrawMoney(int PersonalBankingId, int amount); public boolean closeSavingsAc(int PersonalBankingId); //Sample 5.04: Find Account & return public SavingsAccount findById(int pid); public void TransferFund( SavingsAccount fromAc, SavingsAccount toAc, int amount); //Sample 6.04: Declare method to Search By Id public SavingsAccount queryById(int personalBankingId); } |
Bean Implementation
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package tube.codingexamples.ejb.statelessbean; import javax.ejb.LocalBean; import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import tube.coding.examples.jpa.entity.SavingsAccount; @Stateless(mappedName = "SavingAcBean") @LocalBean public class SavingAcBean implements SavingAcBeanRemote { //Sample 3.6: Create Entiry Manager //UnitName is from persistance.xml @PersistenceContext(unitName = "JPASavingAccount") EntityManager em; public SavingAcBean() {} //Sample 3.8: Create New Account public int newAccount(String accountHolderName, int initialBalance) { SavingsAccount account = new SavingsAccount(); account.setBal(initialBalance); account.setpName(accountHolderName); em.persist(account); return account.getPid(); } //Sample 4.00b: Deposit amount to Bank Account @Override public int depositMoney(int PersonalBankingId, int amount) { //Sample 4.20: Find the Account & call deposit on JPA SavingsAccount SavingAc = em.find(SavingsAccount.class, PersonalBankingId); return SavingAc.deposit(amount); } //Sample 4.00c: Withdraw amount from Savings Account public int withdrawMoney(int PersonalBankingId, int amount) { //Sample 4.21: Find the account & Call withdraw on JPA SavingsAccount SavingAc = em.find(SavingsAccount.class, PersonalBankingId); return SavingAc.withdraw(amount); } //Sample 4.00d: Close the account. public boolean closeSavingsAc(int PersonalBankingId) { //Sample 4.22: Find the account and delete the record. Note=> em.remove boolean ret = false; SavingsAccount SavingAc = em.find(SavingsAccount.class, PersonalBankingId); if (SavingAc != null) { em.remove(SavingAc); ret = true; } return ret; } //Sample 5.05: Find account by id and return it @Override public SavingsAccount findById(int pid) { SavingsAccount SavingAc = em.find(SavingsAccount.class,pid); return SavingAc; } //Sample 5.06: Perform Fund Transfer @Override public void TransferFund(SavingsAccount fromAc, SavingsAccount toAc, int amount) { //5.03.1: First Change the From Account SavingsAccount ac1 = em.merge(fromAc); ac1.withdraw(amount); //5.03.2: Now Change the To Account SavingsAccount ac2 = em.merge(toAc); ac2.deposit(amount); } //Sample 6.05: Use Entity manager to filter account by id public SavingsAccount queryById(int personalBankingId) { SavingsAccount SavingAc = em.find(SavingsAccount.class, personalBankingId); return SavingAc; } } |
Presentation Layer (JSP)
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<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%> <!-- Sample 6.08: Required below imports --> <%@ page import="tube.coding.examples.jpa.entity.SavingsAccount" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> <title>Insert title here</title> </head> <body> <% //Sample 6.09: Get the JPA Account instance from the Request Context SavingsAccount account = (SavingsAccount) request.getAttribute("Account"); %> <!-- Sample 6.10: Present the output to Browser --> <h1> Query By Id : Result</h1> <div style="font-size: large; color: blue; background-color: aliceblue; font-family: Verdana;"> The account id <span style="text-decoration: underline;"> <%= account.getPid() %> </span> is owned by <span style="text-decoration: underline;"> <%= account.getpName() %> </span> . Balance is: <span style="text-decoration: underline;"> <%= account.getBal() %> . </span> </div> </body> </html> |
Categories: JavaEE-EJB-Tube
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