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：

 

 

<?xml version="1.0"?>

<project name="hello" default="prepare" basedir=".">

 

    <property environment="env" />

    <property name="src.dir" value="${basedir}/src" />

    <property name="jboss.home" value="${env.jboss_home}" />

    <property name="build.dir" value="${basedir}/build" />

    <property name="classes.dir" value="${build.dir}/classes" />

    <property name="dist.dir" value="${basedir}/dist" />

 

    <path id="compile.classpath">

       <pathelement location="${classes.dir}" />

       <fileset dir="${jboss.home}/client">

           <include name="jboss-j2ee.jar" />

           <include name="javax.servlet.jar" />

           <include name="commons-httpclient.jar" />

       </fileset>

    </path>

 

    <target name="prepare">

       <mkdir dir="${classes.dir}" />

       <mkdir dir="${dist.dir}" />

       <copy todir="${build.dir}">

           <fileset dir="${src.dir}">

              <include name="web-inf/*.xml" />

              <include name="meta-inf/*.xml" />

           </fileset>

       </copy>

    </target>

 

    <target name="clean">

       <delete dir="${build.dir}" />

       <delete dir="${dist.dir}" />

    </target>

 

    <target name="compile" depends="prepare">

       <javac srcdir="${src.dir}" destdir="${classes.dir}">

           <classpath refid="compile.classpath" />

       </javac>

    </target>

 

    <target name="jar" depends="compile">

       <jar destfile="${dist.dir}/helloejb.jar">

           <fileset dir="${build.dir}">

              <exclude name="meta-inf/application.xml" />

              <include name="meta-inf/*.xml" />

           </fileset>

           <fileset dir="${classes.dir}">

              <include name="**/*.class" />

           </fileset>

       </jar>

    </target>

 

    <target name="war" depends="jar">

       <jar destfile="${dist.dir}/helloejb.war">

           <fileset dir="${build.dir}">

              <include name="web-inf/*.xml" />

           </fileset>

       </jar>

    </target>

 

    <target name="ear" depends="war">

       <jar destfile="${dist.dir}/helloejb.ear">

           <fileset dir="${dist.dir}">

              <include name="helloejb.jar" />

              <include name="helloejb.war" />

           </fileset>

           <fileset dir="${build.dir}">

              <include name="meta-inf/application.xml" />

           </fileset>

       </jar>

    </target>

 

    <target name="deploy" depends="ear">

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

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

    </target>

 

</project>

 

 

package powerwind;

 

import java.rmi.remoteexception;

import javax.ejb.ejbobject;

 

publicinterface hello extends ejbobject {

    public string sayhello() throws remoteexception;

}

 

package powerwind;

 

import java.rmi.remoteexception;

import javax.ejb.createexception;

import javax.ejb.ejbhome;

 

publicinterface hellohome extends ejbhome {

    public hello create() throws remoteexception, createexception;

}

 

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 

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);

    }

 

}

 

 

 

<?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>

       <session>

           <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>

 

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

<jboss>

    <enterprise-beans>

       <session>

           <ejb-name>helloejb</ejb-name>

           <jndi-name>helloejb</jndi-name>

       </session>

    </enterprise-beans>

</jboss>

 

<?xml version="1.0"?>

<application>

    <display-name>helloejb j2ee application</display-name>

    <module>

       <web>

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

           <context-root>/helloejb</context-root>

       </web>

    </module>

    <module>

       <ejb>helloejb.jar</ejb>

    </module>

</application>

 

<?xml version="1.0"?>

<jboss-web>

    <ejb-ref>

       <ejb-ref-name>helloejb</ejb-ref-name>

       <jndi-name>helloejb</jndi-name>

    </ejb-ref>

</jboss-web>

 

<?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>

       <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 ?cdeploy 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。