Lösungsvorschläge zum Übungsblatt 13: Fortgeschrittene Aspekte objektorientierter Programmierung (WS 2005/06)

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1 Prof. Dr. A. Poetzsch-Heffter Dipl.-Inform. N. Rauch Technische Universität Kaiserslautern Fachbereich Informatik AG Softwaretechnik Lösungsvorschläge zum Übungsblatt 13: Fortgeschrittene Aspekte objektorientierter Programmierung (WS 2005/06) Aufgabe 1 EJB Remote Interface: Stellt die Methoden der Bean zur Verwendung durch Clients bereit. / Copyright 2006 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. package samples.ejb.stateless.simple.ejb; Remote interface for the GreeterEJB. The remote interface defines all possible business methods for the bean. These are the methods going to be invoked remotely by clients, once they have a reference to the remote interface. Clients (GreeterServlet, in this case), generally take the help of JNDI to lookup the bean s home interface (GreeterHome, in this case) and then use the home interface to obtain references to the bean s remote interface (Greeter, in this case). public interface Greeter extends javax.ejb.ejbobject { Returns a returns a greeting as a throws a RemoteException. public String getgreeting() throws java.rmi.remoteexception; Home Interface: Erlaubt den Clients, Zugriff auf eine Bean zu bekommen (durch das Remote Interface). / Copyright 2006 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. package samples.ejb.stateless.simple.ejb; Home interface for the GreeterEJB. Clients generally use home interface to obtain references to the bean s remote interface. public interface GreeterHome extends javax.ejb.ejbhome { Gets a reference to the remote interface to the Greeter throws CreateException and RemoteException. public Greeter create() throws java.rmi.remoteexception, javax.ejb.createexception;

2 Implementierung: Der Code der Enterprise Java Bean selbst. / Copyright 2006 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. package samples.ejb.stateless.simple.ejb; import java.util.; import java.io.; A simple stateless bean for the HelloWorld application. This bean implements one business method as declared by the remote interface. public class GreeterEJB implements javax.ejb.sessionbean { private javax.ejb.sessioncontext m_ctx = null; Sets the session context. Required by EJB ctx A SessionContext object. public void setsessioncontext(javax.ejb.sessioncontext ctx) { m_ctx = ctx; Creates a bean. Required by EJB throws CreateException. public void ejbcreate() throws javax.ejb.ejbexception, javax.ejb.createexception { System.out.println("ejbCreate() on obj " + this); Removes the bean. Required by EJB spec. public void ejbremove() { System.out.println("ejbRemove() on obj " + this); Loads the state of the bean from secondary storage. Required by EJB spec. public void ejbactivate() { System.out.println("ejbActivate() on obj " + this); Serializes the state of the bean to secondary storage. Required by EJB spec. public void ejbpassivate() { System.out.println("ejbPassivate() on obj " + this); Required by EJB spec. public void Greeter() { 2

3 Returns a greeting, based on the time of the returns a greeting as a string. public String getgreeting() { String message = null; Calendar calendar = new GregorianCalendar(); int currenthour = calendar.get(calendar.hour_of_day); if(currenthour < 12) message = "morning"; else { if( (currenthour >= 12) && (calendar.get(calendar.hour_of_day) < 18)) message = "afternoon"; else message = "evening"; return message; Client: Ein Beispielclient (hier ein HTTP-Servlet). Zuerst beschafft sich der Client eine Referenz auf das home interface der Bean, dann erzeugt er eine Referenz auf das remote interface der Bean. Anschließend kann er auf die Methoden (= Geschäftslogik) der Bean zugreifen. / Copyright 2006 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. package samples.ejb.stateless.simple.servlet; import java.io.; import java.util.; import javax.servlet.; import javax.naming.; import javax.servlet.http.; import javax.rmi.portableremoteobject; import javax.ejb.; import samples.ejb.stateless.simple.ejb.; This servlet is responsible for throwing the html pages for the HelloWorld application. public class GreeterServlet extends HttpServlet { The doget method of the servlet. Handles all http GET request. Required by the servlet throws ServletException and IOException. public void doget (HttpServletRequest request,httpservletresponse response) throws ServletException, IOException { javax.ejb.handle beanhandle; Greeter mygreeterbean; GreeterHome mygreeterhome; Greeter mygreeterremote; InitialContext initcontext = null; Hashtable env = new java.util.hashtable(1); ResourceBundle rb = ResourceBundle.getBundle("LocalStrings", Locale.getDefault()); System.out.println("\n"+rb.getString("greeting_servlet")+ "..."); System.out.println(rb.getString("retrieving_jndi")); try { initcontext = new javax.naming.initialcontext(); 3

4 catch (Exception e) { System.out.println(rb.getString("exception")+": " + e.tostring()); try { System.out.println(rb.getString("looking_up")); String JNDIName = "java:comp/env/ejb/greeter"; System.out.println(rb.getString("looking")+": " + JNDIName); Object objref = initcontext.lookup(jndiname); mygreeterhome = (GreeterHome)PortableRemoteObject.narrow(objref, GreeterHome.class); catch(exception e) { System.out.println(rb.getString("greeter_bean")+" - " + rb.getstring("is_registered")+"?: " + e.tostring()); try { System.out.println(rb.getString("creating")); mygreeterremote = mygreeterhome.create(); catch(createexception e) { System.out.println(rb.getString("could_not")+": "+ e.tostring()); System.out.println(rb.getString("getting")); String themessage = mygreeterremote.getgreeting(); System.out.println(rb.getString("got")+": " + themessage); System.out.println(rb.getString("storing")); request.setattribute("message", themessage); System.out.println(rb.getString("dispatching")); response.setcontenttype("text/html"); RequestDispatcher dispatcher; dispatcher = getservletcontext().getrequestdispatcher ("/GreeterView.jsp"); dispatcher.include(request, response); The dopost method of the servlet. Handles all http POST request. Required by the servlet throws ServletException and IOException. public void dopost (HttpServletRequest request,httpservletresponse response) throws ServletException, IOException { doget(request,response); Returns the servlet info as a returns the servlet info as a String. public String getservletinfo() { ResourceBundle rb = ResourceBundle.getBundle("LocalStrings", Locale.getDefault()); return rb.getstring("call")+"."; Die wichtigsten Auszüge aus dem Buildfile: 4

5 <!-- Tagets to build and deploy sample application --> <target name="init" depends="init_common" /> <target name="compile" depends="compile_common" /> <target name="jar" depends="init,create_ejbjar_common"/> <target name="core" depends="compile,jar" /> <!-- Taken from common makefile --> <target name="init_common" depends="build_cpath"> <!-- define these properties if samples dont define --> <property name="classpath.prefix" value="."/>... <!-- Classpath and environment --> <target name="build_cpath" unless="appserver.cpath"> <path id="sample_classpath_jars"> <fileset dir="${com.sun.aas.installroot/lib" includes=".jar" /> <fileset dir="${com.sun.aas.webserviceslib" includes=".jar"/> <fileset dir="${com.sun.aas.imqlib" includes=".jar"/> <fileset dir="${com.sun.aas.javaroot/lib" includes="tools.jar"/> </path> <pathconvert pathsep=":" property="appserver.cpath" refid="sample_classpath_jars"/> <!-- Compile all classes. --> <target name="compile_common" depends="init_common"> <mkdir dir="${build.classesdir"/> <echo message="compiling source files into ${build.classesdir" /> <javac srcdir="${src" destdir="${build.classesdir" classpath="${build.classpath"/> <!-- Assemble EJB JAR module. --> <target name="check_ejbjarfile"> <available file="${build.classesdir/${jar.pkg/" type="dir" property="ejbjarfiles.present"/> <target name="add_sharejar_to_ejb_jar" if="sharejar.done"> <jar destfile="${assemble.ejbjar/${ejbjar" update="true"> <zipfileset dir="../${sample.name${sharejar-dir-suffix/${assemble.sharejar" includes="${sharejar"/> <target name="add_shareclasses_to_ejb_jar" if="sharejar.done"> <jar destfile="${assemble.ejbjar/${ejbjar" update="true"> <zipfileset dir="../${sample.name${sharejar-dir-suffix/${build/classes/" includes=".class" excludes="servlet/"/> <target name="add_wsdlfiles_to_ejb_jar" if="iswebserviceclient"> 5

6 <jar destfile="${assemble.ejbjar/${ejbjar" update="true"> <zipfileset dir="../${sample.name${ejbjar-dir-suffix/${src.conf" includes="${wsdlfile" prefix="meta-inf/wsdl/"/> <zipfileset dir="../${sample.name${ejbjar-dir-suffix/${build/shared" includes="mapping.xml" prefix="shared/"/> <target name="add_classes_to_ejb_jar"> <jar destfile="${assemble.ejbjar/${ejbjar" update="true"> <zipfileset dir="${build.classesdir/" includes=".class" excludes="servlet/, client/"/> <metainf dir="${jardd.dir" includes="${jardd"/> <target name="mkdir_ejbjar_common"> <mkdir dir="${assemble.ejbjar"/> <target name="create_ejbjar_common" depends="clean_ejbjar_common,mkdir_ejbjar_common,compile_common,add_classes_to_ejb_jar, add_shareclasses_to_ejb_jar,add_wsdlfiles_to_ejb_jar"> <property name="ejbjar.done" value="true"/> <target name="clean_ejbjar_common"> <delete dir="${assemble.ejbjar"/> </project> Deployment Descriptors: <?xml version = "1.0" encoding = "UTF-8"?> <!-- Copyright Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. --> <ejb-jar xmlns = " version = "2.1" xmlns:xsi = " <display-name>greeterjar</display-name> <enterprise-beans> <session> <display-name>thegreeter</display-name> <ejb-name>thegreeter</ejb-name> <home>samples.ejb.stateless.simple.ejb.greeterhome</home> <remote>samples.ejb.stateless.simple.ejb.greeter</remote> <ejb-class>samples.ejb.stateless.simple.ejb.greeterejb</ejb-class> <session-type>stateless</session-type> <transaction-type>bean</transaction-type> <security-identity> <use-caller-identity/> </security-identity> </session> </enterprise-beans> </ejb-jar> <?xml version="1.0" encoding="utf-8"?> <!DOCTYPE sun-ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Application Server 8.1 EJB 2.1//EN" "h <!-- Copyright Sun Microsystems, Inc. Use is subject to license terms. --> All rights reserved. 6

7 <sun-ejb-jar> <enterprise-beans> <unique-id>1</unique-id> <ejb> <ejb-name>thegreeter</ejb-name> <jndi-name>greeter</jndi-name> </ejb> </enterprise-beans> </sun-ejb-jar> 7