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"？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
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（本文来源于图老师网站，更多请访问http://m.tulaoshi.com/bianchengyuyan/） java源文件Hello.javapackage powerwind; import java.rmi.RemoteException;import javax.ejb.EJBObject; publicinterface Hello extends EJBObject { public String sayHello() throws RemoteException;} HelloHome.javapackage powerwind; import java.rmi.RemoteException;import javax.ejb.CreateException;import javax.ejb.EJBHome; publicinterface HelloHome extends EJBHome { public Hello create() throws RemoteException, CreateException;} HelloBean.javapackage 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.javapackage 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); } }
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（本文来源于图老师网站，更多请访问http://m.tulaoshi.com/bianchengyuyan/） 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 descriptionHelloEJB,my first ejb program/description display-nameHelloEJB/display-name enterprise-beans session ejb-nameHelloEJB/ejb-name homepowerwind.HelloHome/home remotepowerwind.Hello/remote ejb-classpowerwind.HelloBean/ejb-class session-typeStateless/session-type transaction-typeContainer/transaction-type /session /enterprise-beans/ejb-jar jboss-jar？xml version="1.0" encoding="UTF-8"？jboss enterprise-beans session ejb-nameHelloEJB/ejb-name jndi-nameHelloEJB/jndi-name /session
/enterprise-beans/jboss application.xml？xml version="1.0"？application display-nameHelloEJB J2EE Application/display-name module web web-uriHelloEJB.war/web-uri context-root/HelloEJB/context-root /web /module module ejbHelloEJB.jar/ejb /module/application jboss-web.xml？xml version="1.0"？jboss-web ejb-ref ejb-ref-nameHelloEJB/ejb-ref-name jndi-nameHelloEJB/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
servlet-nameClientServlet/servlet-name servlet-classpowerwind.ClientServlet/servlet-class /servlet servlet-mapping servlet-nameClientServlet/servlet-name url-pattern/ClientServlet/url-pattern /servlet-mapping ejb-ref ejb-ref-nameHelloEJB/ejb-ref-name ejb-ref-typeSession/ejb-ref-type homepowerwind.HelloHome/home remotepowerwind.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。
