jboss4.x下的第一个ejb2.0程序(1)---一个简单的无状态sessionBean

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EJB JBoss Bean XML log4j

了解这个例子的前提是对jboss的熟悉，和对ejb的略微了解。

Hello.jar的文件组织是这样的：

1.三个类

　com.rox.Hello(SessionBean)

com.rox.HelloHome(EJBHome,接口)

com.rox.HelloWorld(EJBObject，接口)

2.配置文件

　META-INF

　　 ejb-jar.xml

jboss.xml

直接把Hello.jar放入jboss的运行目录(deploy)中，配置成功．

以下是各个文件的内容:

Hello.java:

package com.rox;

import java.rmi.RemoteException;

import javax.ejb.EJBException;
import javax.ejb.SessionBean;
import javax.ejb.SessionContext;

/**
* XDoclet-based session bean. The class must be declared
* public according to the EJB specification.
*
* To generate the EJB related files to this EJB:
*  - Add Standard EJB module to XDoclet project properties
*  - Customize XDoclet configuration for your appserver
*  - Run XDoclet
*
* Below are the xdoclet-related tags needed for this EJB.
*
* @ejb.bean name="Hello"
*           display-name="Name for Hello"
*           description="Description for Hello"
*           jndi-name="ejb/Hello"
*           type="Stateless"
*           view-type="remote"
*/
public class Hello implements SessionBean {

/** The session context */
private SessionContext context;

    public Hello() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * Set the associated session context. The container calls this method
     * after the instance creation.
     *
     * The enterprise bean instance should store the reference to the context
     * object in an instance variable.
     *
     * This method is called with no transaction context.
     *
     * @throws EJBException Thrown if method fails due to system-level error.
     */
    public void setSessionContext(SessionContext newContext)
        throws EJBException {
        context = newContext;
    }
    public void ejbCreate() throws EJBException, RemoteException {
        // TODO Auto-generated method stub
       System.out.println("ejb create");
    }
    public void ejbRemove() throws EJBException, RemoteException {
        // TODO Auto-generated method stub

}

public void ejbActivate() throws EJBException, RemoteException {
// TODO Auto-generated method stub

}

public void ejbPassivate() throws EJBException, RemoteException {
// TODO Auto-generated method stub

}

    /**
     * An example business method
     *
     * @ejb.interface-method view-type = "remote"
     *
     * @throws EJBException Thrown if method fails due to system-level error.
     */
    public String sayIt() throws EJBException {
        System.out.println("hello didi");
        return "hello didi.";
    }

}

HelloHome.java:

package com.rox;

/**
* Home interface for Hello.
* @xdoclet-generated at ${TODAY}
* @copyright The XDoclet Team
* @author XDoclet
* @version ${version}
*/
public interface HelloHome
   extends javax.ejb.EJBHome
{
   public static final String INITIAL_NAME="ejb/HelloWorld";
   public static final String COMP_NAME="java:comp/env/ejb/HelloWorld";
   public static final String JNDI_NAME="ejb/HelloWorld";

public com.rox.HelloWorld create()
throws javax.ejb.CreateException,java.rmi.RemoteException;

}

HelloWorld.java:

package com.rox;

import java.rmi.RemoteException;

import javax.ejb.EJBObject;

public interface HelloWorld extends EJBObject{
public String sayIt() throws RemoteException;
}

ejb-jar.xml:

http://java.sun.com/dtd/ejb-jar_2_0.dtd">

<ejb-jar></ejb-jar>

<description></description>
<display-name></display-name>Generated by XDoclet

<enterprise-beans></enterprise-beans>

<session></session>
         <description></description>
         <display-name></display-name>Name for Hello

<ejb-name></ejb-name>HelloWorld

         <home></home>com.rox.HelloHome
         <remote></remote>com.rox.HelloWorld
         <ejb-class></ejb-class>com.rox.Hello
         <session-type></session-type>Stateless
         <transaction-type> </transaction-type> Container

<assembly-descriptor></assembly-descriptor>

jboss.xml:

http://www.jboss.org/j2ee/dtd/jboss_2_4.dtd">

<enterprise-beans></enterprise-beans>

      <session></session>
         <ejb-name></ejb-name>HelloWorld
         <jndi-name></jndi-name>ejb/HelloWorld

<resource-managers></resource-managers>

只是配置完了，服务器没有报错，并不能说明问题．下面我们写一个测试的客户端程序EjbTest.java:

package com.rox;

import java.rmi.RemoteException;
import java.util.Hashtable;
import java.util.Properties;

import javax.ejb.CreateException;
import javax.naming.Context;
import javax.naming.NamingException;

public class EjbTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        javax.naming.InitialContext initialContext = null;
        Properties environment = new Properties();
        environment.put(Context.PROVIDER_URL, "localhost:1099");
        environment.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
        environment.put(Context.URL_PKG_PREFIXES, "org.jboss.naming:org.jnp.interfaces");
        try {
            initialContext = new javax.naming.InitialContext(environment);
        } catch (NamingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return;
        }
        HelloHome helloHome = null;
        try {
            Object obj = initialContext.lookup("ejb/HelloWorld");
            helloHome = (HelloHome)javax.rmi.PortableRemoteObject.narrow(obj, HelloHome.class);
        } catch (ClassCastException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (NamingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            HelloWorld hello = helloHome.create();
            System.out.println(hello.sayIt());
        } catch (RemoteException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (CreateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

注意：由于上面environment.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
这句话中用到了org.jnp.interfaces.NamingContextFactory类，所以应当确保｛JBOSS_HOME｝/client下的jbossall-client.jar位于classpath中．

运行EjbTest，输出结果：hello didi.
稍后我将结合该例子研究log4j,据说很简单的