Característica |
Session Bean |
Entity Bean |
| O que o Bean representa |
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| Tempo de vida |
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| Atributos |
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| Persistência (além da sessão) |
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| Compartilhamento |
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| Criação |
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| Durabilidade |
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| Transação |
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| Exemplo |
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Característica |
Stateful Session Bean |
Stateless Session Bean |
| Gerência de estado |
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| Responsabilidades |
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| Performance |
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| Exemplo |
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CREATE TABLE BOOKS
CODE Number
TITLE Text
AUTHORS Text
PRICE Currency
DISCOUNT Number
*primary key (CODE)
package com.gopalan.Shop.Books;
import javax.ejb.*;
import java.rmi.*;
interface BooksHome extends EJBHome {
Books create(int isbn, String title,
String authors, double price,
int discount
throws CreateException, RemoteException;
Books findByPrimaryKey(BooksPK book)
throws FinderException, RemoteException;
}
package com.gopalan.Shop.Books;
import javax.ejb.*;
import java.rmi.*;
interface Books extends EJBObject {
int getIsbn() throws RemoteException;
String getTitle() throws RemoteException;
String getAuthors() throws RemoteException;
double getPrice() throws RemoteException;
int getDiscount() throws RemoteException;
double getDiscountedPrice() throws RemoteException;
void setPrice(double cost) throws RemoteException;
void setDiscount(int disc) throws RemoteException;
}
package com.gopalan.Shop.Books;
public class BooksPK implements java.io.Serializable {
public int isbn;
public BooksPK() {
}
public BooksPK(int isbn) {
this.isbn = isbn;
}
}
package com.gopalan.Shop.Books;
import java.rmi.*;
import javax.ejb.*;
public class BooksBean implements EntityBean {
EntityContext entityContext;
public int code; // CODE
public String title; // TITLE
public String authors; // AUTHORS
public double price; // PRICE
public int discount; // DISCOUNT
// Implementação de todos os Business Methods
// da Remote Interface
public int getIsbn() throws RemoteException {
return code;
}
public String getTitle() throws RemoteException {
return title;
}
public String getAuthors() throws RemoteException {
return authors;
}
public double getPrice() throws RemoteException {
return price;
}
public int getDiscount() throws RemoteException {
return discount;
}
public double getDiscountedPrice() throws RemoteException {
double deduct = ( (double)discount)/100;
return price* (1-deduct);
}
public void setPrice(double cost) throws RemoteException {
price = cost;
}
public void setDiscount(int disc) throws RemoteException {
discount = disc;
}
// Implementação de todos os métodos para a Home Interface
public void ejbCreate(int isbn, String bookTitle,
String author, double cost,
int disc)
throws CreateException, RemoteException {
code = isbn;
title = bookTitle;
authors = author;
price = cost;
discount= disc;
}
public void ejbPostCreate(int isbn, String bookTitle,
String author, double cost,
int disc) {
}
// Implementação de outros métodos necessários com EJB
// ejbLoad() e ejbStore fazem nada porque estamos usando
// Container-managed persistence
public void ejbLoad() throws RemoteException {}
public void ejbStore() throws RemoteException {}
public void ejbActivate() throws RemoteException {}
public void ejbPassivate() throws RemoteException {}
public void ejbRemove()
throws RemoteException, RemoveException {}
public void setEntityContext(EntityContext context)
throws RemoteException {
entityContext = context;
}
public void unsetEntityContext() throws RemoteException {
entityContext = null;
}
}
javac *.java
<!------------------------------------------>
<!------- Books Entity Bean ---------------->
<!------------------------------------------>
<ejbml>
<entity-bean
name="Books"
descriptor="Books/BooksDeployment"
package="com.gopalan.Shop.Books"
home="com.gopalan.Shop.Books.BooksHome"
remote="com.gopalan.Shop.Books.Books"
bean="com.gopalan.Shop.Books.BooksBean"
primary-key="com.gopalan.Shop.Books.BooksPK"
tx-attribute="TX_SUPPORTS"
>
<property
name="databasePassword"
value="mouse"
/>
<property
name="dataSourceName"
value="Shop"
/>
<property
name="databaseUser"
value="user"
/>
<property
name="databaseTable"
value="books"
/>
<container-managed
storage-helper=
"com.ejbhome.generator.helpers.RelationalPersistenceCodeHelper"
table="books"
data-source="Shop"
user="user"
password="mouse"
>
<field name="discount" />
<field name="price" />
<field name="authors" />
<field name="title" />
<field name="code" />
</container-managed>
</entity-bean>
</ejbml>
E:\>javac *.java E:\>java com.ejbhome.Deployer .\conf\Shop.ejbml EJBHome EJB Deployer version 0.5.1 (Scunthorpe) (c) Copyright IONA Technologies PLC 1999. All Rights Reserved. Windows NT x86 4.0 Deploying: Books... Generating: IonaBooksHome...done. Generating: IonaRemoteBooks...done. Generating: IonaBooksBean...done. Generating: IonaBooksContext...done. Implementing Communications: Home Stubs & Skels...done. Implementing Communications: Remote Stubs & Skels...done. Compiling: IonaBooksHome.java...done. Compiling: IonaRemoteBooks.java...done. Compiling: IonaBooksBean.java...done. Compiling: IonaBooksContext.java...done. Compiling: IonaBooksHome_Stub.java...done. Compiling: IonaBooksHome_Skel.java...done. Compiling: IonaRemoteBooks_Stub.java...done. Compiling: IonaRemoteBooks_Skel.java...done. Deploying: Music... Generating: IonaMusicHome...done. Generating: IonaRemoteMusic...done. Generating: IonaMusicBean...done. Generating: IonaMusicContext...done. Implementing Communications: Home Stubs & Skels...done. Implementing Communications: Remote Stubs & Skels...done. Compiling: IonaMusicHome.java...done. Compiling: IonaRemoteMusic.java...done. Compiling: IonaMusicBean.java...done. Compiling: IonaMusicContext.java...done. Compiling: IonaMusicHome_Stub.java...done. Compiling: IonaMusicHome_Skel.java...done. Compiling: IonaRemoteMusic_Stub.java...done. Compiling: IonaRemoteMusic_Skel.java...done. Deploying: Cart... Generating: IonaCartHome...done. Generating: IonaRemoteCart...done. Generating: IonaCartBean...done. Generating: IonaCartContext...done. Implementing Communications: Home Stubs & Skels...done. Implementing Communications: Remote Stubs & Skels...done. Compiling: IonaCartHome.java...done. Compiling: IonaRemoteCart.java...done. Compiling: IonaCartBean.java...done. Compiling: IonaCartContext.java...done. Compiling: IonaCartHome_Stub.java...done. Compiling: IonaCartHome_Skel.java...done. Compiling: IonaRemoteCart_Stub.java...done. Compiling: IonaRemoteCart_Skel.java...done. E:\>
java com.ejbhome.Server
package com.gopalan.Shop.Books;
import java.rmi.*;
import java.util.*;
public class BooksTest {
static final int NUMBOOKS = 4;
public static void main(String[] args) throws Exception {
// Usa JNDI para achar o Home do Bean
BooksHome home = (BooksHome)Naming.lookup("Books");
System.out.println("Naming.lookup successful...");
if(home == null) {
System.out.println("null BooksHome returned...");
}
String title = "Book";
String author = "Author";
Vector v = new Vector();
for(int i = 0; i < BooksTest.NUMBOOKS; i++) {
System.out.println("ISBN = " + (i+1) +
" Book = " +title+ (i+1) +
" Author = " +author+ (i+1) +
" Creating home.create...");
v.add(home.create((i+1),title+(i+1),
author+(i+1),100.00,10));
}
for(int i = 0; i < BooksTest.NUMBOOKS; i++) {
Books books = (Books)(v.get(i));
books.setPrice(books.getPrice()+1);
System.out.println("Final Price of " +
books.getTitle() +
" is "+ books.getPrice());
}
System.out.println("Books.setBooksPrice successful...");
for(int i = 0; i < BooksTest.NUMBOOKS; i++) {
Books books = (Books)(home.findByPrimaryKey(
new BooksPK(i+1)));
books.setPrice(books.getPrice()+1);
System.out.println("Final Price of " +
books.getTitle() +
" is "+ books.getPrice());
}
System.out.println("Books.findByPrimaryKey successful...");
}
}
package com.gopalan.Shop.Cart;
import javax.ejb.*;
import java.rmi.*;
interface CartHome extends EJBHome {
Cart create() throws RemoteException, CreateException;
}
package com.gopalan.Shop.Cart;
import javax.ejb.*;
import java.rmi.*;
import java.util.*;
import com.gopalan.Shop.Books.*;
import com.gopalan.Shop.Music.*;
interface Cart extends EJBObject {
Books createNewBook(int isbn, String title, String authors,
double price, int discount)
throws RemoteException, CreateException;
Music createNewAlbum(int code, String album, String authors,
double price, int discount)
throws RemoteException, CreateException;
Books getBook(int isbn)
throws RemoteException, FinderException;
Music getAlbum(int code)
throws RemoteException, FinderException;
void addToBooksCart(int code) throws RemoteException;
void addToMusicCart(int code) throws RemoteException;
void flushBooksCart() throws RemoteException;
void flushMusicCart() throws RemoteException;
int getNumberBooks() throws RemoteException;
int getNumberAlbums() throws RemoteException;
double getBooksTotal() throws RemoteException;
double getAlbumsTotal() throws RemoteException;
double getGrandTotal() throws RemoteException;
// Não gostei de retornar vector aqui ...
// Cria um acoplamento desnecessário
// melhor seria usar Iterator
Vector getBooksList() throws RemoteException;
Vector getMusicList() throws RemoteException;
Vector getBooksCart() throws RemoteException;
Vector getMusicCart() throws RemoteException;
}
// Estou estranhando a visibilidade de muitas coisas mas
// não que mexer até conhecer EJB melhor e testar tudo
package com.gopalan.Shop.Cart;
import java.rmi.*;
import javax.ejb.*;
import java.util.*;
import com.gopalan.Shop.Books.*;
import com.gopalan.Shop.Music.*;
import com.gopalan.Shop.Cart.ReturnSet;
public class CartBean implements SessionBean {
SessionContext sessionContext;
public BooksHome booksHome;
public MusicHome musicHome;
public Vector booksList = null, booksCart = null;
public Vector musicList = null, musicCart = null;
int totalBooks = 0, totalMusic = 0;
double booksCost = 0, musicCost = 0, grandTotal = 0;
void init() {
booksList = new Vector();
booksCart = new Vector();
musicList = new Vector();
musicCart = new Vector();
ReturnSet result = null;
for(int i=0; ;i++) {
try {
BooksPK key = new BooksPK(i+1);
Books found = booksHome.findByPrimaryKey(key);
if(null == found) {
break;
}
result = new ReturnSet(key.code, found.getTitle(),
found.getAuthors(),
found.getPrice(),
found.getDiscount(),
found.getDiscountedPrice());
System.out.println("isbn = "+ result.code +
" Title = "+result.title+
" Authors = "+result.authors+
" Price = " + result.price);
booksList.add(result);
} catch(Exception e) {
e.printStackTrace();
break;
}
}
for(int i=0; ;i++) {
try {
MusicPK key = new MusicPK(i+1);
Music found = musicHome.findByPrimaryKey(key);
if(found == null) {
break;
}
result = new ReturnSet(key.code, found.getAlbum(),
found.getComposers(),
found.getPrice(),
found.getDiscount(),
found.getDiscountedPrice());
System.out.println("code = "+ result.code +
" Album = "+result.title+
" Composers = "+result.authors+
" Price = " + result.price);
musicList.add(result);
} catch(Exception e) {
e.printStackTrace();
break;
}
}
}
// Implementação de todos os BUsiness Methods
// da interface Remote
public Books createNewBook(int isbn, String title,
String authors, double price,
int discount)
throws RemoteException, CreateException {
Books book = booksHome.create(isbn, title, authors,
price, discount);
if(null != book) {
booksList.add(new ReturnSet(isbn, title,
authors,
price, discount,
book.getDiscountedPrice()));
}
return book;
}
public Music createNewAlbum(int code, String album,
String authors,
double price, int discount)
throws RemoteException, CreateException {
Music music = musicHome.create(code, album, authors,
price, discount);
if(null != music) {
musicList.add(new ReturnSet(code, album, authors,
price, discount,
music.getDiscountedPrice()));
}
return music;
}
public void addToBooksCart(int isbn) throws RemoteException {
try {
Books book = getBook(isbn);
if(null != book) {
booksCart.add(new ReturnSet(isbn,
book.getTitle(),
book.getAuthors(),
book.getPrice(),
book.getDiscount(),
book.getDiscountedPrice()));
++totalBooks;
booksCost += book.getDiscountedPrice();
grandTotal+= book.getDiscountedPrice();
}
} catch(Exception e) {
e.printStackTrace();
}
}
public void flushBooksCart() throws RemoteException {
grandTotal -= booksCost;
totalBooks = 0;
booksCost = 0;
booksCart.removeAllElements();
}
public void flushMusicCart() throws RemoteException {
grandTotal -= musicCost;
totalMusic = 0;
musicCost = 0;
musicCart.removeAllElements();
}
public void addToMusicCart(int code) throws RemoteException {
try {
Music music = getAlbum(code);
if(null != music) {
musicCart.add(new ReturnSet(code, music.getAlbum(),
music.getComposers(),
music.getPrice(),
music.getDiscount(),
music.getDiscountedPrice()));
++totalMusic;
musicCost += music.getDiscountedPrice();
grandTotal+= music.getDiscountedPrice();
}
} catch(Exception e) {
e.printStackTrace();
}
}
public Books getBook(int isbn)
throws RemoteException, FinderException {
return booksHome.findByPrimaryKey(new BooksPK(isbn));
}
public Music getAlbum(int code)
throws RemoteException, FinderException {
return musicHome.findByPrimaryKey(new MusicPK(code));
}
public Vector getBooksList() throws RemoteException {
return booksList;
}
public Vector getMusicList() throws RemoteException {
return musicList;
}
public Vector getBooksCart() throws RemoteException {
return booksCart;
}
public Vector getMusicCart() throws RemoteException {
return musicCart;
}
public int getNumberBooks() throws RemoteException {
return totalBooks;
}
public int getNumberAlbums() throws RemoteException {
return totalMusic;
}
public double getBooksTotal() throws RemoteException {
return booksCost;
}
public double getAlbumsTotal() throws RemoteException {
return musicCost;
}
public double getGrandTotal() throws RemoteException {
return grandTotal;
}
// Implementação dos métodos da Home Interface
public void ejbCreate()
throws RemoteException, CreateException {
}
// Outros métodos exigidos pela especificação EJB
public void ejbActivate() throws RemoteException {}
public void ejbPassivate() throws RemoteException {}
public void ejbRemove() throws RemoteException {}
public void setSessionContext(SessionContext context)
throws RemoteException {
sessionContext = context;
try {
booksHome =(BooksHome)Naming.lookup("Books");
musicHome = (MusicHome)Naming.lookup("Music");
init();
} catch(Exception ex) {
throw new RemoteException("Shop not found", ex);
}
}
}
package com.gopalan.Shop.Cart;
public class ReturnSet implements java.io.Serializable {
// por que ele usou public?
public int code;
public String title;
public String authors;
public double price;
public int discount;
public double ourPrice;
public ReturnSet(int no, String name, String author,
double cost, int disc, double cp) {
code = no; title = name; authors = author;
price = cost; discount = disc; ourPrice = cp;
}
}
java *.java
<!------------------------------------------>
<!------- Cart Session Bean ---------------->
<!------------------------------------------>
<ejbml>
<session-bean
name="cart"
descriptor="Cart/CartDeployment"
package="com.gopalan.Shop.Cart"
home="com.gopalan.Shop.Cart.CartHome"
remote="com.gopalan.Shop.Cart.Cart"
bean="com.gopalan.Shop.Cart.CartBean"
type="stateful"
timeout="3600"
tx-attribute="TX_SUPPORTS"
></session-bean>
</ejbml>
package com.gopalan.Shop.Cart;
import java.rmi.*;
import java.util.*;
public class CartTest {
static final int NUMITEMS = 2;
public static void main (String[] args) throws Exception {
CartHome home = (CartHome)Naming.lookup("Cart");
System.out.println("Naming.lookup successful...");
if(null == home) {
System.out.println ("null CartHome returned...");
}
Cart cart = home.create();
String title = "Title";
String author= "Author";
for(int i = 0; i < CartTest.NUMITEMS; i++) {
System.out.println("code = " +(i+1) +
" Title = " +title+(i+1) +
" Author = " +author+(i+1) +
" Creating cart.create...");
cart.createNewBook((i+1),title+(i+1),
author+(i+1),100.00,10);
cart.createNewAlbum((i+1),title+(i+1),
author+(i+1),20.00,5);
}
for(int i = 0; i < CartTest.NUMITEMS; i++) {
cart.addToBooksCart(i+1);
cart.addToMusicCart(i+1);
}
Vector bookList = cart.getBooksList();
System.out.println ("Book List of size "+
bookList.size()+" is...");
for(int i = 0; i < bookList.size(); i++) {
ReturnSet set = (ReturnSet)bookList.get(i);
System.out.println("code = " +set.code +
" Title = " +set.title +
" Author = " +set.authors);
}
Vector musicList= cart.getMusicList();
System.out.println ("Music List of size "+
musicList.size()+" is...");
for(int i = 0; i < musicList.size(); i++) {
ReturnSet set = (ReturnSet)musicList.get(i);
System.out.println("code = " +set.code +
" Title = " +set.title +
" Author = " +set.authors);
}
Vector bookCart = cart.getBooksCart();
System.out.println ("Book Cart of size "+
bookCart.size()+" is...");
for(int i = 0; i < bookCart.size(); i++) {
ReturnSet set = (ReturnSet)bookCart.get(i);
System.out.println("code = " +set.code +
" Title = " +set.title +
" Author = " +set.authors);
}
Vector musicCart = cart.getMusicCart();
System.out.println("Music Cart of size "+
musicCart.size ()+" is...");
for(int i = 0; i < musicCart.size(); i++) {
ReturnSet set = (ReturnSet)musicCart.get(i);
System.out.println("code = " +set.code +
" Title = " +set.title +
" Author = " +set.authors);
}
System.out.println("Total Books = " + cart.getNumberBooks() +
" Total Albums = " +cart.getNumberAlbums () +
" Book Cost = " +cart.getBooksTotal () +
" Album Cost = " +cart.getAlbumsTotal () +
" Grand Total =" + cart.getGrandTotal ());
}
}
JavaBeans |
Enterprise JavaBeans |
| JavaBeans podem ser visíveis ou não em tempo de execução | Um EJB é um objeto remoto não visual |
| JavaBeans rodam num único processo e foram feitos
basicamente para rodarem no cliente. É possível usar JavaBeans no servidor mas é melhor usar EJB |
EJBs são componentes executáveis remotamente e só podem executar no servidor |
| Com JavaBeans, eventos são fundamentais: são a base da interconexão de componentes | Eventos não são importantes em EJB.
Outras propriedades (persistência, concorrência, segurança, etc.) são importantes Não há relação entre os dois modelos de componentes |
| JavaBeans têm uma interface externa (Properties) que permite que uma ferramenta interprete a funcionalidade do Bean | EJBs têm um Deployment Descriptor que descreve sua funcionalidade, ou pelo menos que parametriza parte do comportamento desejado que o Container tem que implementar |
| JavaBeans podem ter classe BeanInfo, Property Editors, ou Customizers. | EJBs não têm esses conceitos e só possuem o Deployment Descriptor |
| JavaBeans não são tipados | Tem dois tipos de EJBs: Entity e Session |
| Há um bridge disponível para implantar um Bean como controle ActiveX | Não se pode transformar um EJB num controle ActiveX |
| Para ser usado como server component, o programador teria que escrever muita funcionalidade adicional | O framework já foi escrito |