EJB3 Entity Bean with JBOSS

Trong ví dụ này, tôi sẽ hướng dẫn cho các bạn cách thức tạo 1 ứng dụng JPA Entity Bean. Ứng dụng đựa trên nguyên tắc cơ bản của kiến trúc 3-tiers. Tầng Presentation (Client) truy xuất đến tầng Business Logic(Session Bean), Business Logic layer truy xuất dữ liệu thông qua Data Service (Entity Bean).

Software cần thiết:

• Eclipse ganymede
• JBoss Application Server 4.2.x

1. Đầu tiên, trong Eclipse bạn tiến hành tạo 1 project kiểu EJB Project. Chọn Target runtime là JBoss. Đặt tên là EJB3_Entity_Products như hình

2. Trong folder META-INF, tạo file persistence.xml với nội dung như sau

<?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="EJB3_Entity_ProductsExample"> <jta-data-source>java:ejb3ProductDS</jta-data-source> <properties> <property name="hibernate.hbm2ddl.auto" value="update" /> <property name="hibernate.dialect" value="org.hibernate.dialect.SQLServerDialect" /> </properties> </persistence-unit> </persistence>

Chú ý: ở đây chúng ta dùng jta-data-source java:ejb3ProductDS nên chúng ta cũng phải cấu hình cho data source này. Chúng ta muốn dùng hệ quản trị database là Microsoft SQL Server 2005 nên ta cần phải có driver cho cơ sở dữ liệu này, Bạn có thể download nó từ Microsoft hoặc download tại đây. Bạn hãy copy nó vào %JBOSS_HOME%\server\default\lib\. Sau đó tạo file mssql-ds.xml trong thư mục %JBOSS_HOME%\server\default\deploy\ (nếu đã có thì hiệu chỉnh file này) với nội dung sau

<?xml version=”1.0″ encoding=”UTF-8″?> <datasources> <local-tx-datasource> <jndi-name>ejb3ProductDS</jndi-name> <connection-url>jdbc:sqlserver://localhost:1433;databaseName=EJB3_JPA_Products</connection-url> <driver-class>com.microsoft.sqlserver.jdbc.SQLServerDriver</driver-class> <user-name>sa</user-name> <password></password> <metadata> <type-mapping>MS SQLSERVER2000</type-mapping> </metadata> </local-tx-datasource> </datasources>

Thuộc tính <property name="hibernate.hbm2ddl.auto" value="update" /> phần value ta có thể có một trong các giá trị: validate | update | create | create-drop.

Thuộc tính <property name="hibernate.dialect" value="org.hibernate.dialect.SQLServerDialect" /> chỉ cho hibernate biết Dialect là của Microsoft SQL Server.

Sau đây là bảng các SQL Dialect của Hibernate

3. Tạo Entity Bean

Tạo package vovanhai.wordpress.com

Tạo lớp Product.java trong gói này với nội dung:

package vovanhai.wordpress.com;import java.io.Serializable; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; @Entity(name=”Product”) public class Product implements Serializable{ private static final long serialVersionUID = 1L; private int productID; private String productName; private String description; private double basePrice; public Product(int productID, String productName, String description, double basePrice) { super(); this.productID = productID; this.productName = productName; this.description = description; this.basePrice = basePrice; } public Product() { this(0,””,””,100f); } @Id @GeneratedValue(strategy=GenerationType.AUTO) public int getProductID() { return productID; } public void setProductID(int productID) { this.productID = productID; } @Column(name=”productName”, nullable=false ) public String getProductName() { return productName; } public void setProductName(String productName) { this.productName = productName; } @Column(name=”description”) public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } @Column(name=”basePrice”, nullable=false) public double getBasePrice() { return basePrice; } public void setBasePrice(double basePrice) { this.basePrice = basePrice; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + productID; return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; Product other = (Product) obj; if (productID != other.productID) return false; return true; } @Override public String toString() { return productID+”; “+productName+”; “+description+”; “+basePrice; } }

4. Tạo Stateless Session Bean

Tạo Remote interface, tập tin ProductRemote.java

package vovanhai.wordpress.com;import java.util.List; import javax.ejb.Remote; @Remote public interface ProductRemote { //Thêm 1 product vào database public void AddNewProduct(Product p); //Xóa 1 product khỏi database public boolean RemoveProduct(int pID); //Lấy tất cả các product từ bảng public List<Product> GetAllProducts(); //Lấy tất cả các sản phẩm có giá dưới giá price public List<Product> GetProductsUnderPrice(double price); }

Tạo Local interface, tập tin ProductLocal.java

package vovanhai.wordpress.com;import java.util.List; import javax.ejb.Local; @Local public interface ProductLocal { public void AddNewProduct(Product p); public boolean RemoveProduct(int pID); public List<Product> GetAllProducts(); public List<Product> GetProductsUnderPrice(double price); }

Tạo Session Bean, tập tin ProductBean.java

package vovanhai.wordpress.com;import java.util.List; import javax.ejb.Stateless; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import javax.persistence.Query; @Stateless public class ProductBean implements ProductRemote{ @PersistenceContext EntityManager em; @Override public void AddNewProduct(Product p) { em.persist(p); } @Override public boolean RemoveProduct(int pID) { Product p=em.find(Product.class, new Integer(pID)); if(p==null) return false; em.remove(p); return true; } @SuppressWarnings(“all”) @Override public List<Product> GetAllProducts() { List<Product> lst=(List<Product>)(em.createQuery(“from Product”).getResultList()); return lst; } @SuppressWarnings(“all”) @Override public List<Product> GetProductsUnderPrice(double price) { Query query=em.createQuery(“from Product as p where p.basePrice< :price”); query.setParameter(“price”, price); List<Product> lst=(List<Product>)query.getResultList(); return lst; } }

OK! Triển khai nó trên JBOSS thôi. kết quả triển khai có dạng

20:36:05,212 INFO  [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.entity.PersistenceUnitDeployment 20:36:05,212 INFO  [JmxKernelAbstraction] installing MBean: persistence.units:jar=EJB3_Entity_Products.jar,unitName=EJB3_Entity_ProductsExample with dependencies: 20:36:05,212 INFO  [JmxKernelAbstraction]     jboss.jca:name=ejb3ProductDS,service=DataSourceBinding 20:36:05,212 INFO  [PersistenceUnitDeployment] Starting persistence unit persistence.units:jar=EJB3_Entity_Products.jar,unitName=EJB3_Entity_ProductsExample 20:36:05,213 INFO  [Ejb3Configuration] found EJB3 Entity bean: vovanhai.wordpress.com.Product 20:36:05,213 INFO  [Configuration] Reading mappings from resource : META-INF/orm.xml 20:36:05,213 INFO  [Ejb3Configuration] [PersistenceUnit: EJB3_Entity_ProductsExample] no META-INF/orm.xml found 20:36:05,213 INFO  [AnnotationBinder] Binding entity from annotated class: vovanhai.wordpress.com.Product 20:36:05,213 INFO  [EntityBinder] Bind entity vovanhai.wordpress.com.Product on table Product 20:36:05,244 INFO  [ConnectionProviderFactory] Initializing connection provider: org.hibernate.ejb.connection.InjectedDataSourceConnectionProvider 20:36:05,244 INFO  [InjectedDataSourceConnectionProvider] Using provided datasource 20:36:06,695 INFO  [SettingsFactory] RDBMS: Microsoft SQL Server, version: 9.00.1399 20:36:06,695 INFO  [SettingsFactory] JDBC driver: Microsoft SQL Server 2005 JDBC Driver, version: 1.2.2828.100 20:36:06,695 INFO  [Dialect] Using dialect: org.hibernate.dialect.SQLServerDialect 20:36:06,710 INFO  [TransactionFactoryFactory] Transaction strategy: org.hibernate.ejb.transaction.JoinableCMTTransactionFactory 20:36:06,710 INFO  [TransactionManagerLookupFactory] instantiating TransactionManagerLookup: org.hibernate.transaction.JBossTransactionManagerLookup 20:36:06,710 INFO  [TransactionManagerLookupFactory] instantiated TransactionManagerLookup 20:36:06,711 INFO  [SettingsFactory] Automatic flush during beforeCompletion(): disabled 20:36:06,711 INFO  [SettingsFactory] Automatic session close at end of transaction: disabled 20:36:06,711 INFO  [SettingsFactory] Scrollable result sets: enabled 20:36:06,711 INFO  [SettingsFactory] JDBC3 getGeneratedKeys(): enabled 20:36:06,711 INFO  [SettingsFactory] Connection release mode: auto 20:36:06,711 INFO  [SettingsFactory] Default batch fetch size: 1 20:36:06,711 INFO  [SettingsFactory] Generate SQL with comments: disabled 20:36:06,711 INFO  [SettingsFactory] Order SQL updates by primary key: disabled 20:36:06,711 INFO  [SettingsFactory] Order SQL inserts for batching: disabled 20:36:06,711 INFO  [SettingsFactory] Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 20:36:06,711 INFO  [ASTQueryTranslatorFactory] Using ASTQueryTranslatorFactory 20:36:06,711 INFO  [SettingsFactory] Query language substitutions: {} 20:36:06,711 INFO  [SettingsFactory] JPA-QL strict compliance: enabled 20:36:06,711 INFO  [SettingsFactory] Second-level cache: enabled 20:36:06,711 INFO  [SettingsFactory] Query cache: disabled 20:36:06,711 INFO  [SettingsFactory] Cache provider: org.hibernate.cache.HashtableCacheProvider 20:36:06,711 INFO  [SettingsFactory] Optimize cache for minimal puts: disabled 20:36:06,711 INFO  [SettingsFactory] Cache region prefix: EJB3_Entity_Products_jar,EJB3_Entity_ProductsExample 20:36:06,711 INFO  [SettingsFactory] Structured second-level cache entries: disabled 20:36:06,711 INFO  [SettingsFactory] Statistics: disabled 20:36:06,711 INFO  [SettingsFactory] Deleted entity synthetic identifier rollback: disabled 20:36:06,711 INFO  [SettingsFactory] Default entity-mode: pojo 20:36:06,711 INFO  [SettingsFactory] Named query checking : enabled 20:36:06,711 INFO  [SessionFactoryImpl] building session factory 20:36:06,711 INFO  [SessionFactoryObjectFactory] Factory name: persistence.units:jar=EJB3_Entity_Products.jar,unitName=EJB3_Entity_ProductsExample 20:36:06,711 INFO  [NamingHelper] JNDI InitialContext properties:{java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory, java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces} 20:36:06,711 INFO  [SessionFactoryObjectFactory] Bound factory to JNDI name: persistence.units:jar=EJB3_Entity_Products.jar,unitName=EJB3_Entity_ProductsExample 20:36:06,711 WARN  [SessionFactoryObjectFactory] InitialContext did not implement EventContext 20:36:06,711 INFO  [SchemaUpdate] Running hbm2ddl schema update 20:36:06,711 INFO  [SchemaUpdate] fetching database metadata 20:36:06,743 INFO  [SchemaUpdate] updating schema 20:36:09,395 INFO  [TableMetadata] table found: EJB3_JPA_Products.dbo.Product 20:36:09,395 INFO  [TableMetadata] columns: [baseprice, productid, description, productname] 20:36:09,395 INFO  [TableMetadata] foreign keys: [] 20:36:09,395 INFO  [TableMetadata] indexes: [pk__product__060deae8] 20:36:09,395 INFO  [SchemaUpdate] schema update complete 20:36:09,395 INFO  [NamingHelper] JNDI InitialContext properties:{java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory, java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces} 20:36:09,396 INFO  [JmxKernelAbstraction] creating wrapper delegate for: org.jboss.ejb3.stateless.StatelessContainer 20:36:09,396 INFO  [JmxKernelAbstraction] installing MBean: jboss.j2ee:jar=EJB3_Entity_Products.jar,name=ProductBean,service=EJB3 with dependencies: 20:36:09,396 INFO  [JmxKernelAbstraction]     persistence.units:jar=EJB3_Entity_Products.jar,unitName=EJB3_Entity_ProductsExample 20:36:09,396 INFO  [EJBContainer] STARTED EJB: vovanhai.wordpress.com.ProductBean ejbName: ProductBean 20:36:09,427 INFO  [EJB3Deployer] Deployed: file:/E:/javaSoft/jboss-4.2.3.GA/server/default/deploy/EJB3_Entity_Products.jar

Thành công rồi!

5. Viết client

Tạo lớp ProductClient với nội dung sau

package vovanhai.wordpress.com;import java.util.List; import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; public class ProductClient { public static void main(String[] args) { System.setProperty(“java.naming.factory.initial”,”org.jnp.interfaces.NamingContextFactory”); System.setProperty( “java.naming.provider.url”, “localhost:1099” ); System.setProperty( “java.naming.factory.url.pkgs”, “org.jboss.naming” ); Context context; try { context = new InitialContext(); String name=”ProductBean/remote”; ProductRemote beanRemote = (ProductRemote)context.lookup(name); //Thêm 1 product mới beanRemote.AddNewProduct(new Product(0,”Xoài”,”Xoài”,4000f)); System.out.println(“Danh sách sản phẩm”); List<Product> lst=beanRemote.GetAllProducts(); for(Product p:lst) System.out.println(p); System.out.println(“Các sp có giá dưới 8000”); lst=beanRemote.GetProductsUnderPrice(8000); for(Product p:lst) System.out.println(p); //Xóa sản phẩm /*if(beanRemote.RemoveProduct(4)) System.out.println(“Xóa thành công SP số 4”); else System.out.println(“Không xóa được sp số 4”);*/ } catch (NamingException e) { e.printStackTrace(); } } }

Thực thi ứng dụng và bạn sẽ ngạc nhiên đấy!

Chúc thành công!