Wie kann ich eine EJB3-Session-Bean in einer JSP aufrufen?

Question

Ich entwickle eine Anwendung in Eclipse mit EJBs und JPA.

My Session Bean ist:

package itso.bank.session; 

import itso.bank.entities.Account; 
import itso.bank.entities.Customer; 
import itso.bank.entities.Transaction; 
import itso.bank.exception.ITSOBankException; 
import itso.bank.service.EJBBankService; 

import java.math.BigDecimal; 
import java.util.Arrays; 
import java.util.List; 

import javax.ejb.Stateless; 
import javax.persistence.*; 

/** 
* Session Bean implementation class EJBBankBean 
*/ 
@Stateless 
public class EJBBankBean implements EJBBankService { 

    @PersistenceContext (unitName="RAD8JPA", type=PersistenceContextType.TRANSACTION) 
    private EntityManager entityMgr; 
    /** 
    * Default constructor. 
    */ 
    public EJBBankBean() { 
     // TODO Auto-generated constructor stub 
    } 

    public void addCustomer(Customer customer) throws ITSOBankException { 
     System.out.println("addCustomer: " + customer.getSsn()); 
     entityMgr.persist(customer); 
    } 

    public void closeAccount(String ssn, String id) throws ITSOBankException { 
     System.out.println("closeAccount: " + id + " of customer " + ssn); 

     Account account = getAccount(id); 
     Transaction[] trans = getTransactions(id); 
     for (Transaction tx : trans) { 
      entityMgr.remove(tx); 
     } 
     entityMgr.remove(account); 
     System.out.println("closed account with " + trans.length + " transactions"); 
    } 

    public void deleteCustomer(String ssn) throws ITSOBankException { 
     System.out.println("deleteCustomer: " + ssn); 
     Customer customer = getCustomer(ssn); 
     Account[] accounts = getAccounts(ssn); 
     for (Account acct : accounts) { 
      closeAccount(ssn, acct.getId()); 
     } 
     entityMgr.remove(customer); 
    } 

    public void deposit(String id, BigDecimal amount) throws ITSOBankException { 
     System.out.println("deposit: " + id + " amount " + amount); 
     Account account = getAccount(id); 
     try { 
      Transaction tx = account.processTransaction(amount, Transaction.CREDIT); 
      entityMgr.persist(tx); 
     } catch (Exception e) { 
      throw new ITSOBankException(e.getMessage());  
     } 
    } 

    public Account getAccount(String id) throws ITSOBankException { 
     System.out.println("getAccount: " + id); 
     try { 
      return entityMgr.find(Account.class, id); 
     } catch (Exception e) { 
      System.out.println("Exception: " + e.getMessage()); 
      throw new ITSOBankException(id); 
     } 
    } 

    public Account[] getAccounts(String ssn) throws ITSOBankException { 
     System.out.println("getAccounts: " + ssn); 
     Query query = null; 
     try { 
      query = entityMgr.createNamedQuery("getAccountsBySSN"); 
      query.setParameter(1, ssn); 
      List<Account> accountList = query.getResultList(); 
      Account[] array = new Account[accountList.size()]; 
      return accountList.toArray(array); 
     } catch (Exception e) { 
      System.out.println("Exception: " + e.getMessage()); 
      throw new ITSOBankException(ssn); 
     } 
    } 

    public Customer getCustomer(String ssn) throws ITSOBankException { 
     System.out.println("getCustomer: " + ssn); 
     //Query query = null; 
     try { 
      //query = entityMgr.createNamedQuery("getCustomerBySSN"); 
      //query.setParameter(1, ssn); 
      //return (Customer)query.getSingleResult(); 
      return entityMgr.find(Customer.class, ssn); 
     } catch (Exception e) { 
      System.out.println("Exception: " + e.getMessage()); 
      throw new ITSOBankException(ssn); 
     } 
    } 

    public Customer[] getCustomers(String partialName) throws ITSOBankException { 
     System.out.println("getCustomer: " + partialName); 
     Query query = null; 
     try { 
      query = entityMgr.createNamedQuery("getCustomersByPartialName"); 
      query.setParameter(1, partialName); 
      List<Customer> beanlist = query.getResultList(); 
      Customer[] array = new Customer[beanlist.size()]; 
      return beanlist.toArray(array); 
     } catch (Exception e) { 
      throw new ITSOBankException(partialName); 
     } 
    } 

    public Customer[] getCustomersAll() { 
     System.out.println("getCustomers: all"); 
     Query query = null; 
     try { 
      query = entityMgr.createNamedQuery("getCustomers"); 
      List<Customer> beanlist = query.getResultList(); 
      Customer[] array = new Customer[beanlist.size()]; 
      return beanlist.toArray(array); 
     } catch (Exception e) { 
      System.out.println("Exception: " + e.getMessage()); 
      return null; 
     } 
    } 

    public Transaction[] getTransactions(String accountID) throws ITSOBankException { 
     System.out.println("getTransactions: " + accountID); 
     Query query = null; 
     try { 
      query = entityMgr.createNamedQuery("getTransactionsByID"); 
      query.setParameter(1, accountID); 
      List<Transaction> transactionsList = query.getResultList(); 
      Transaction[] array = new Transaction[transactionsList.size()]; 
      return transactionsList.toArray(array); 
     } catch (Exception e) { 
      System.out.println("Exception: " + e.getMessage()); 
      e.printStackTrace(); 
      throw new ITSOBankException(accountID); 
     } 
    } 

    public String openAccount(String ssn) throws ITSOBankException { 
     System.out.println("openAccount: " + ssn); 
     Customer customer = getCustomer(ssn); 
     int acctNumber = (new java.util.Random()).nextInt(899999) + 100000; 
     String id = "00" + ssn.substring(0, 1) + "-" + acctNumber; 
     Account account = new Account(); 
     account.setId(id); 
     entityMgr.persist(account); 

     List<Customer> custSet = Arrays.asList(customer); 
     account.setCustomers(custSet); 
     System.out.println("openAccount: " + id); 
     return id; 
    } 

    public void transfer(String idDebit, String idCredit, BigDecimal amount) throws ITSOBankException { 
     System.out.println("transfer: " + idCredit + " " + idDebit + " amount " + amount); 
     withdraw(idDebit, amount); 
     deposit(idCredit, amount); 
    } 

    public void updateCustomer(String ssn, String title, String firstName, String lastName) throws ITSOBankException { 
     System.out.println("updateCustomer: " + ssn); 
     Customer customer = getCustomer(ssn); 
     customer.setTitle(title); 
     customer.setLastName(lastName); 
     customer.setFirstName(firstName); 
     System.out.println("updateCustomer: " + customer.getTitle() + " " + customer.getFirstName() + " " + customer.getLastName()); 
    } 

    public void withdraw(String id, BigDecimal amount) throws ITSOBankException { 
     System.out.println("withdraw: " + id + " amount " + amount); 
     Account account = getAccount(id); 
     try { 
      Transaction tx = account.processTransaction(amount, Transaction.DEBIT); 
      entityMgr.persist(tx); 
     } catch (Exception e) { 
      throw new ITSOBankException(e.getMessage());  
     } 
    } 


} 

Meine JPA bereits mit dem EJB-Projekt verbunden. Meine Frage ist, wie ich die Session-Bean von einer Java Server Page aufrufen kann, ohne Servlets?

Vielen Dank!

Answer 1

Ich vermute, es muss einen Grund geben, kein MVC-Framework zu verwenden.

Also, angenommen, Sie eine lokale Schnittstelle verwenden, ist dies die sauberste und Standard, wie ich aus einem .jsp zum Aufrufen eines ejb erinnern

<ejb-local-ref> 
    <ejb-ref-name>MyBeanName</ejb-ref-name> 
    <ejb-ref-type>Session</ejb-ref-type> 
    <local>com.myapp.ejb.MyBeanLocal</local> 
</ejb-local-ref> 

Dann von Ihrem jsp

<% 
String lookupUrl = "java:comp/env/MyBeanName"; 
Context ctx = new javax.naming.InitialContext(); 
MyBeanNameLocal ejbLocal = (MyBeanNameLocal) ctx.lookup(lookupUrl); 

String output = ejbLocal.myBusinessMethod(); 
%> 

Answer 2

einfach Anmerken, Service Implementation Klasse von @Named Anmerkung

@Stateless 
@Named("eJBBankBean") 
public class EJBBankBean implements EJBBankService {....} 

In Verwendung Ihrer JSP-Datei,: #{ejbBankBean.yourServiceMethod(parameter1_ifAny,parameter2_ifAny)}

@Named ist CDI Annotation, ohne @Named EJB Bean wird nicht sichtbar in JSP EL d '$' oder Unified-EL d '#'