基于jboss的ejb3开发入门总结

基于jboss的ejb3开发入门总结
1.关于jboss版本
  刚开始使用的是5.0以上版本,每次启动均报错,后来采用jboss-4.2.3.GA-jdk6版本才能够正常运行.
  在eclipse中设置jboss服务器时需要重新指定jboss jdk name.
  如果使用默认myeclipse jdk, 在myeclipse中启动jboss会报错.
  而独立运行run.bat启动是没有问题地,why?
2.完整的ejb应用程序开发一般分为两部分:
      服务器端的ejb程序,这部分程序一般发布在远程的j2ee服务器端,比如jboss
      客户端程序.如jsp/servlet,java application。基于jndi获取j2ee服务器端ejb提供的服务.非分布式环境下,客户端程序和EJB是在同一容器中的
  ejb是基于RMI和JNDI的
3.Session Bean有两种接口:remote接口和local接口(对应@Remote和@Local)
  romote接口:允许来自EJB容器外的程序访问
  local接口: 允许来自相同EJB容器的程序访问,没有分布式开销,提高了性能.
  ps:调用local接口时要保证客户端程序和EJB程序在同一EJB容器中.比如:可以采用jsp作客户端的调用程序,并发布在jboss中
4.Stateful session Bean和Stateless session Bean
  前者每次lookup操作都会重新创建一个bean实例,适用用于需要保存对象状态情形,比如用户购物车
  后者实例化后被放入实例池中被所有用户共享.

5.实体bean简单例子
//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目录下, --> <?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>

//调用: 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.学习资料
  黎活明《EJB3.0实例教程》
 《EJB3.0 In Action》
  http://blog.youkuaiyun.com/pathuang68/archive/2009/04/24/4108254.aspx
  http://blog.youkuaiyun.com/caterpillar_here/archive/2008/10/16/3087399.aspx