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Jboss4.x下第一个EJB2.x程序

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EJB的名声很不好，尤其在Spring框架出现以后，而EJB3似乎脱胎换骨了。而我现在学习的仍然是EJB2，原因是EJB3的书很难找。

作者：中国IT实验室来源：中国IT实验室 2007年9月6日

关键字： JBoss

EJB的名声很不好，尤其在Spring框架出现以后，而EJB3似乎脱胎换骨了。而我现在学习的仍然是EJB2，原因是EJB3的书很难找。暑假时大概把《精通EJB》和《EJB》这两本书看过一下，现在想复习，加深理解，就从第一个HelloWorld开始。

文件结构：

E:.

│ build.xml

│

└─src

├─META-INF

│ application.xml

│ ejb-jar.xml

│ jboss.xml

│

├─powerwind

│ ClientServlet.java

│ Hello.java

│ HelloBean.java

│ HelloHome.java

│

└─WEB-INF

jboss-web.xml

web.xml

ant文件

build.xml

<?xml version="1.0"?>

</fileset>

</path>

</fileset>

</copy>

</target>

</target>

</javac>

</target>

</fileset>

</fileset>

</jar>

</target>

</fileset>

</jar>

</target>

</fileset>

</fileset>

</jar>

</target>

<copy file="${dist.dir}/HelloEJB.ear" overwrite="true"

todir="${jboss.home}/server/default/deploy" />

</target>

</project>

java源文件

Hello.java

package powerwind;

import java.rmi.RemoteException;

import javax.ejb.EJBObject;

publicinterface Hello extends EJBObject {

public String sayHello() throws RemoteException;

}

HelloHome.java

package powerwind;

import java.rmi.RemoteException;

import javax.ejb.CreateException;

import javax.ejb.EJBHome;

publicinterface HelloHome extends EJBHome {

public Hello create() throws RemoteException, CreateException;

}

HelloBean.java

package powerwind;

import java.rmi.RemoteException;

import javax.ejb.EJBException;

import javax.ejb.SessionBean;

import javax.ejb.SessionContext;

publicclass HelloBean implements SessionBean {

private SessionContext context;

publicvoid ejbCreate() throws EJBException, RemoteException {

}

publicvoid ejbActivate() throws EJBException, RemoteException {

}

publicvoid ejbPassivate() throws EJBException, RemoteException {

}

publicvoid ejbRemove() throws EJBException, RemoteException {

}

publicvoid setSessionContext(SessionContext newContext)

throws EJBException {

context = newContext;

}

public String sayHello() throws EJBException {

return"Hello from ejb";

}

用于测试的Servlet

ClientServlet.java

package powerwind;

import java.io.IOException;

import java.io.PrintWriter;

import javax.naming.InitialContext;

import javax.rmi.PortableRemoteObject;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

publicclass ClientServlet extends HttpServlet {

publicvoid doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

response.setContentType("text/html");

PrintWriter out = response.getWriter();

String message = null;

try {

InitialContext ic = new InitialContext();

Object obj = ic.lookup("HelloEJB");

HelloHome home = (HelloHome) PortableRemoteObject.narrow(obj,

powerwind.HelloHome.class);

Hello hello = home.create();

message = hello.sayHello();

} catch (Exception e) {

e.printStackTrace();

}

out.println(message);

out.flush();

out.close();

}

publicvoid doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request, response);

}

配置文件：

ejb-jar.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE ejb-jar PUBLIC '-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN' 'http://java.sun.com/dtd/ejb-jar_2_0.dtd'>

<ejb-jar>

<description>HelloEJB,my first ejb program</description>

<display-name>HelloEJB</display-name>

<enterprise-beans>

<ejb-name>HelloEJB</ejb-name>

<home>powerwind.HelloHome</home>

<remote>powerwind.Hello</remote>

<ejb-class>powerwind.HelloBean</ejb-class>

<session-type>Stateless</session-type>

<transaction-type>Container</transaction-type>

</session>

</enterprise-beans>

</ejb-jar>

jboss-jar

<?xml version="1.0" encoding="UTF-8"?>

<jboss>

<enterprise-beans>

<ejb-name>HelloEJB</ejb-name>

<jndi-name>HelloEJB</jndi-name>

</session>

</enterprise-beans>

</jboss>

application.xml

<?xml version="1.0"?>

<display-name>HelloEJB J2EE Application</display-name>

<web>

<web-uri>HelloEJB.war</web-uri>

<context-root>/HelloEJB</context-root>

</web>

</module>

<ejb>HelloEJB.jar</ejb>

</module>

</application>

jboss-web.xml

<?xml version="1.0"?>

<jboss-web>

<ejb-ref>

<ejb-ref-name>HelloEJB</ejb-ref-name>

<jndi-name>HelloEJB</jndi-name>

</ejb-ref>

</jboss-web>

web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<servlet-name>ClientServlet</servlet-name>

<servlet-class>powerwind.ClientServlet</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>ClientServlet</servlet-name>

<url-pattern>/ClientServlet</url-pattern>

</servlet-mapping>

<ejb-ref>

<ejb-ref-name>HelloEJB</ejb-ref-name>

<ejb-ref-type>Session</ejb-ref-type>

<home>powerwind.HelloHome</home>

<remote>powerwind.Hello</remote>

</ejb-ref>

</web-app>

输入 ant –deploy 部署，启动Jboss服务器，在浏览器地址栏输入：

http://localhost:8080/HelloEJB/ClientServlet

然后看到浏览器输出“Hello from ejb”，就是成功了。

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