基於jboss的ejb3開發入門總結

基於jboss的ejb3開發入門總結
1.關於jboss版本
  剛開始使用的是5.0以上版本,每次啓動均報錯,後來採用jboss-4.2.3.GA-jdk6版本才能夠正常運行.
  在eclipse中設置jboss服務器時需要重新指定jboss jdk name.
  如果使用默認myeclipse jdk, 在myeclipse中啓動jboss會報錯.
  而獨立運行run.bat啓動是沒有問題地,why?
2.完整的ejb應用程序開發一般分爲兩部分:
      服務器端的ejb程序,這部分程序一般發佈在遠程的j2ee服務器端,比如jboss
      客戶端程序.如jsp/servlet,java application。基於jndi獲取j2ee服務器端ejb提供的服務.非分佈式環境下,客戶端程序和EJB是在同一容器中的
  ejb是基於RMI和JNDI的
3.Session Bean有兩種接口:remote接口和local接口(對應@Remote和@Local)
  romote接口:允許來自EJB容器外的程序訪問
  local接口: 允許來自相同EJB容器的程序訪問,沒有分佈式開銷,提高了性能.
  ps:調用local接口時要保證客戶端程序和EJB程序在同一EJB容器中.比如:可以採用jsp作客戶端的調用程序,併發布在jboss中
4.Stateful session Bean和Stateless session Bean
  前者每次lookup操作都會重新創建一個bean實例,適用用於需要保存對象狀態情形,比如用戶購物車
  後者實例化後被放入實例池中被所有用戶共享.

5.實體bean簡單例子
//Student.java @Entity @Table(name="student") public class Student implements Serializable { @Id @GeneratedValue(strategy=GenerationType.AUTO) @Column(name="id") private Integer id; @Column(name="gender") private Integer gender; @Column(name="stu_no") private String stuNo; @Column(name="department") private String department; @Column(name="name") private String name; //setter //getter } //StudentDao.java public interface StudentDao { public void create(Student stu); public Student findById(int id); } //StudentDaoImpl.java @Remote(StudentDao.class) @Stateless public class StudentDaoImpl implements StudentDao { @PersistenceContext(unitName="mysqlTest")protected EntityManager em; public void create(Student stu) { em.persist(stu); } public Student findById(int id) { return em.find(Student.class, id); } }

 

<!--META-INF/persistence.xml --> <?xml version="1.0" encoding="UTF-8"?> <persistence 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" version="1.0"> <persistence-unit name="mysqlTest" transaction-type="JTA"> <jta-data-source>java:/MySqlDS</jta-data-source> <properties> <property name="hibernate.hbm2ddl.auto" value="update" /> </properties> </persistence-unit> </persistence> <!-- mysql_ds.xml 直接放在jboss_home/server/default/deploy目錄下, --> <?xml version="1.0" encoding="UTF-8"?> <datasources> <local-tx-datasource> <jndi-name>MySqlDS</jndi-name> <connection-url>jdbc:mysql://localhost:3306/test</connection-url> <driver-class>com.mysql.jdbc.Driver</driver-class> <user-name>root</user-name> <password></password> <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.MySQLExceptionSorter</exception-sorter-class-name> <metadata> <type-mapping>mySQL</type-mapping> </metadata> </local-tx-datasource> </datasources>

//調用: Properties props = new Properties(); props.setProperty("java.naming.factory.initial", "org.jnp.interfaces.NamingContextFactory"); props.setProperty("java.naming.provider.url", "localhost"); props.setProperty("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces"); InitialContext context = new InitialContext(props); Student stu = new Student(); stu.setGender(1); stu.setStuNo("xxxxx"); stu.setName("wokkkk"); stu.setDepartment("cs"); StudentDao sDao = (StudentDao)context.lookup("StudentDaoImpl/remote"); sDao.create(stu); Student rstu = sDao.findById(2); out.println(rstu.getName()+":"+rstu.getStuNo());
6.學習資料
  黎活明《EJB3.0實例教程》
 《EJB3.0 In Action》
  http://blog.csdn.net/pathuang68/archive/2009/04/24/4108254.aspx
  http://blog.csdn.net/caterpillar_here/archive/2008/10/16/3087399.aspx