EJB創建應用

要創建一個簡單的EJB模塊,我們這裏使用NetBeans「 New project」嚮導。在下面的例子中,我們將創建一個名爲「 Component」的EJB模塊項目。

創建項目

在NetBeans IDE中,選擇File > New Project >. 可以看到如下圖.

在類別中選擇項目類型,Java EE的EJB模塊項目類型。點擊Next>按鈕,你會看到以下的畫面。

輸入項目的名稱和位置。點擊Next>按鈕。你會看到以下的畫面。

選擇服務器爲JBoss應用服務器。單擊「Finish」按鈕。你會看到以下由NetBeans創建的項目。

創建一個簡單的EJB

要創建一個簡單的EJB,我們將使用NetBeans「New」嚮導。在下面的例子中,我們將在EjbComponent項目下創建一個無狀態EJB類名爲librarySessionBean

在項目資源管理器窗口中選擇項目EjbComponent,右鍵單擊它。選擇New > Session Bean。您將看到新的會話Bean嚮導。

輸入會話bean的名稱和包名。單擊「Finish 」按鈕。你會看到以下由NetBeans創建的EJB類。

  • LibrarySessionBean - 無狀態會話bean

  • LibrarySessionBeanLocal - 本地接口的會話bean

要改變本地接口,我們要一個基於控制檯的應用程序訪問我們的EJB遠程接口。遠程/本地接口用於公開一個EJB的業務方法實現。

LibrarySessionBeanLocal更名爲LibrarySessionBeanRemote和LibrarySessionBean實現LibrarySessionBeanRemote接口。

LibrarySessionBeanRemote

package com.tutorialspoint.stateless; import java.util.List; import javax.ejb.Remote; @Remote public interface LibrarySessionBeanRemote { void addBook(String bookName); List getBooks(); }

LibrarySessionBean

package com.tutorialspoint.stateless; import java.util.ArrayList; import java.util.List; import javax.ejb.Stateless; @Stateless public class LibrarySessionBean implements LibrarySessionBeanRemote { List<String> bookShelf; public LibrarySessionBean(){ bookShelf = new ArrayList<String>(); } public void addBook(String bookName) { bookShelf.add(bookName); } public List<String> getBooks() { return bookShelf; } }

構建項目

  • Project Explorer窗口中選擇EjbComponent項目。

  • 右鍵點擊它來打開上下文菜單。

  • 選擇 clean and build。

在NetBeans控制檯輸出,你會看到以下的輸出。

ant -f C:\EJB\EjbComponent clean dist init: undeploy-clean: deps-clean: Deleting directory C:EJBEjbComponentuild Deleting directory C:EJBEjbComponentdist clean: init: deps-jar: Created dir: C:EJBEjbComponentuildclasses Copying 3 files to C:EJBEjbComponentuildclassesMETA-INF Created dir: C:EJBEjbComponentuildempty Created dir: C:EJBEjbComponentuildgenerated-sourcesap-source-output Compiling 2 source files to C:EJBEjbComponentuildclasses warning: [options] bootstrap class path not set in conjunction with -source 1.6 Note: C:EJBEjbComponentsrcjavacom utorialspointstateless LibraryPersistentBean.java uses unchecked or unsafe operations. Note: Recompile with -Xlint:unchecked for details. 1 warning compile: library-inclusion-in-archive: Created dir: C:EJBEjbComponentdist Building jar: C:EJBEjbComponentdistEjbComponent.jar dist: BUILD SUCCESSFUL (total time: 3 seconds)

啓動應用程序服務器

  • 服務器在服務窗口下選擇JBoss應用服務器。

  • 右鍵點擊它來打開上下文菜單。

  • 選擇start

你會看到下面的輸出在NetBeans中JBoss應用服務器下的輸出。

Calling C:jboss-5.1.0.GAin

un.conf.bat

JBoss Bootstrap Environment

JBOSS_HOME: C:jboss-5.1.0.GA

JAVA: C:Program Files (x86)Javajdk1.6.0_21injava

JAVA_OPTS: -Dprogram.name=run.bat -Xms128m -Xmx512m -server

CLASSPATH: C:jboss-5.1.0.GAin un.jar

=========================================================================

16:25:50,062 INFO [ServerImpl] Starting JBoss (Microcontainer)... 16:25:50,062 INFO [ServerImpl] Release ID: JBoss [The Oracle] 5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221634) ...

16:26:40,420 INFO [TomcatDeployment] deploy, ctxPath=/admin-console 16:26:40,485 INFO [config] Initializing Mojarra (1.2_12-b01-FCS) for context '/admin-console' 16:26:42,362 INFO [TomcatDeployment] deploy, ctxPath=/ 16:26:42,406 INFO [TomcatDeployment] deploy, ctxPath=/jmx-console 16:26:42,471 INFO [Http11Protocol] Starting Coyote HTTP/1.1 on http-127.0.0.1-8080 16:26:42,487 INFO [AjpProtocol] Starting Coyote AJP/1.3 on ajp-127.0.0.1-8009 16:26:42,493 INFO [ServerImpl] JBoss (Microcontainer) [5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221634)] Started in 52s:427ms

部署項目

  • Project Explorer窗口中選擇EjbComponent項目。

  • 右擊它,打開上下文菜單。

  • 選擇 Deploy.

在NetBeans控制檯輸出,你會看到下面的輸出。

ant -f C:\EJB\EjbComponent -DforceRedeploy=true -Ddirectory.deployment.supported=false -Dnb.wait.for.caches=true run init: deps-jar: compile: library-inclusion-in-archive: Building jar: C:EJBEjbComponentdistEjbComponent.jar dist-directory-deploy: pre-run-deploy: Checking data source definitions for missing JDBC drivers... Distributing C:EJBEjbComponentdistEjbComponent.jar to [[email protected]] Deploying C:EJBEjbComponentdistEjbComponent.jar Applicaton Deployed Operation start started Operation start completed post-run-deploy: run-deploy: run: BUILD SUCCESSFUL (total time: 2 seconds)

JBoss應用服務器的日誌輸出

16:30:00,963 INFO [DeployHandler] Begin start, [EjbComponent.jar] ... 16:30:01,233 INFO [Ejb3DependenciesDeployer] Encountered deployment [email protected]{vfszip:/C:/jboss-5.1.0.GA/server/default/deploy/EjbComponent.jar/} ... 16:30:01,281 INFO [JBossASKernel] jndi:LibrarySessionBean/remote-com.tutorialspoint.stateless.LibrarySessionBeanRemote 16:30:01,281 INFO [JBossASKernel] Class:com.tutorialspoint.stateless.LibrarySessionBeanRemote 16:30:01,281 INFO [JBossASKernel] jndi:LibrarySessionBean/remote 16:30:01,281 INFO [JBossASKernel] Added bean(jboss.j2ee:jar=EjbComponent.jar,name= LibrarySessionBean,service=EJB3) to KernelDeployment of: EjbComponent.jar 16:30:01,282 INFO [JBossASKernel] installing bean: jboss.j2ee:jar=EjbComponent.jar,name=BookMessageHandler,service=EJB3 16:30:01,282 INFO [JBossASKernel] with dependencies: 16:30:01,282 INFO [JBossASKernel] and demands: 16:30:01,282 INFO [JBossASKernel] jboss.ejb:service=EJBTimerService ... 16:30:01,283 INFO [EJB3EndpointDeployer] Deploy [email protected]{name=jboss.j2ee:jar=EjbComponent.jar, name=LibrarySessionBean, service=EJB3_endpoint bean=org.jboss.ejb3.endpoint.deployers.impl.EndpointImpl properties=[container] constructor=null autowireCandidate=true} ... 16:30:01,394 INFO [SessionSpecContainer] Starting jboss.j2ee:jar=EjbComponent.jar,name=LibrarySessionBean,service=EJB3 16:30:01,395 INFO [EJBContainer] STARTED EJB: com.tutorialspoint.stateless.LibrarySessionBean ejbName: LibrarySessionBean 16:30:01,401 INFO [JndiSessionRegistrarBase] Binding the following Entries in Global JNDI: LibrarySessionBean/remote - EJB3.x Default Remote Business Interface LibrarySessionBean/remote-com.tutorialspoint.stateless.LibrarySessionBeanRemote - EJB3.x Remote Business Interface 16:30:02,723 INFO [SessionSpecContainer] Starting jboss.j2ee:jar=EjbComponent.jar,name=LibrarySessionBean,service=EJB3 16:30:02,723 INFO [EJBContainer] STARTED EJB: com.tutorialspoint.stateless.LibrarySessionBean ejbName: LibrarySessionBean 16:30:02,731 INFO [JndiSessionRegistrarBase] Binding the following Entries in Global JNDI:

LibrarySessionBean/remote - EJB3.x Default Remote Business Interface LibrarySessionBean/remote-com.tutorialspoint.stateless.LibrarySessionBeanRemote - EJB3.x Remote Business Interface

創建客戶端訪問EJB

  • 在NetBeans IDE中選擇 File > New Project >.

  • 類別下選擇項目類型爲Java,項目類型爲Java應用程序的Java。點擊Next>按鈕。

  • 輸入項目的名稱和位置。單擊「Finish >「按鈕。我們選擇名爲EjbTester。

  • 右鍵點擊項目名稱(在Project explore窗口中)。選擇屬性properties

  • 添加EJB組件項目的庫使用「Add Project 」按鈕,在compile選項卡下創建的。

  • 添加JBoss庫使用添加Add jar/folder按鈕,在compile選項卡。 Jboss的庫可以位於<JBOSS安裝文件夾>客戶端文件夾。

在工程中創建 jndi.properties說一個句話 EjbTester.

jndi.properties

java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces java.naming.provider.url=localhost

創建包com.tutorialspoint.test和EJBTester.java類在下面。

EJBTester.java

package com.tutorialspoint.test; import com.tutorialspoint.stateless.LibrarySessionBeanRemote; import java.io.BufferedReader; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStreamReader; import java.util.List; import java.util.Properties; import javax.naming.InitialContext; import javax.naming.NamingException; public class EJBTester { BufferedReader brConsoleReader = null; Properties props; InitialContext ctx; { props = new Properties(); try { props.load(new FileInputStream("jndi.properties")); } catch (IOException ex) { ex.printStackTrace(); } try { ctx = new InitialContext(props); } catch (NamingException ex) { ex.printStackTrace(); } brConsoleReader = new BufferedReader(new InputStreamReader(System.in)); } public static void main(String[] args) { EJBTester ejbTester = new EJBTester(); ejbTester.testStatelessEjb(); } private void showGUI(){ System.out.println("**********************"); System.out.println("Welcome to Book Store"); System.out.println("**********************"); System.out.print("Options

  1. Add Book
  2. Exit Enter Choice: "); } private void testStatelessEjb(){ try { int choice = 1; LibrarySessionBeanRemote libraryBean = (LibrarySessionBeanRemote)ctx.lookup("LibrarySessionBean/remote"); while (choice != 2) { String bookName; showGUI(); String strChoice = brConsoleReader.readLine(); choice = Integer.parseInt(strChoice); if (choice == 1) { System.out.print("Enter book name: "); bookName = brConsoleReader.readLine(); libraryBean.addBook(bookName); }else if (choice == 2) { break; } } List<String> booksList = libraryBean.getBooks(); System.out.println("Book(s) entered so far: " + booksList.size()); for (int i = 0; i < booksList.size(); ++i) { System.out.println((i+1)+". " + booksList.get(i)); } LibrarySessionBeanRemote libraryBean1 = (LibrarySessionBeanRemote)ctx.lookup("LibrarySessionBean/remote"); List<String> booksList1 = libraryBean1.getBooks(); System.out.println( "***Using second lookup to get library stateless object***"); System.out.println( "Book(s) entered so far: " + booksList1.size()); for (int i = 0; i < booksList1.size(); ++i) { System.out.println((i+1)+". " + booksList1.get(i)); } } catch (Exception e) { System.out.println(e.getMessage()); e.printStackTrace(); }finally { try { if(brConsoleReader !=null){ brConsoleReader.close(); } } catch (IOException ex) { System.out.println(ex.getMessage()); } } } }

運行客戶端訪問EJB

project explorer中找到EJBTester.java。右鍵點擊上EJBTester類,並選擇「run file」。

在Netbeans控制檯驗證以下輸出。

run: ********************** Welcome to Book Store ********************** Options

  1. Add Book
  2. Exit Enter Choice: 1 Enter book name: Learn Java ********************** Welcome to Book Store ********************** Options
  3. Add Book
  4. Exit Enter Choice: 2 Book(s) entered so far: 1
  5. Learn Java ***Using second lookup to get library stateless object*** Book(s) entered so far: 0 BUILD SUCCESSFUL (total time: 13 seconds)

在下面的章節中,我們將討論這個完整的EJB的多個層面應用程序。