EJB - 创建应用程序

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为了创建一个简单的 EJB 模块，我们将使用 NetBeans 的“新建项目”向导。在下面给出的示例中，我们将创建一个名为 Component 的 EJB 模块项目。

创建项目

在 NetBeans IDE 中，选择“文件”>“新建项目”>。您将看到以下屏幕

在类别Java EE下选择项目类型，项目类型为EJB Module。单击下一步 >按钮。您将看到以下屏幕。

输入项目名称和位置。单击下一步 >按钮。您将看到以下屏幕。

选择服务器作为JBoss 应用程序服务器。单击完成按钮。您将看到 NetBeans 创建的以下项目。

创建示例 EJB

为了创建一个简单的 EJB，我们将使用 NetBeans“新建”向导。在下面给出的示例中，我们将在 EjbComponent 项目下创建一个名为librarySessionBean 的无状态 EJB 类。

在项目资源管理器窗口中选择项目 EjbComponent 并右键单击它。选择新建 > 会话 Bean。您将看到新建会话 Bean向导。

输入会话 bean 名称和包名称。单击完成按钮。您将看到 NetBeans 创建的以下 EJB 类。

• LibrarySessionBean - 无状态会话 bean

• LibrarySessionBeanLocal - 会话 bean 的本地接口

我将本地接口更改为远程接口，因为我们将在基于控制台的应用程序中访问 EJB。远程/本地接口用于公开 EJB 必须实现的业务方法。

LibrarySessionBeanLocal 重命名为 LibrarySessionBeanRemote，并且 LibrarySessionBean 实现了 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();
}

库会话Bean

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;
   }
}

构建项目

• 在 Project Explorer 窗口中选择 EjbComponent 项目。
• 右键单击它以打开上下文菜单。
• 选择清理并构建。

您将在 NetBeans 控制台输出中看到以下输出。

ant -f C:\\EJB\\EjbComponent clean dist
init:
undeploy-clean:
deps-clean:
Deleting directory C:\EJB\EjbComponent\build
Deleting directory C:\EJB\EjbComponent\dist
clean:
init:
deps-jar:
Created dir: C:\EJB\EjbComponent\build\classes
Copying 3 files to C:\EJB\EjbComponent\build\classes\META-INF
Created dir: C:\EJB\EjbComponent\build\empty
Created dir: C:\EJB\EjbComponent\build\generated-sources\ap-source-output
Compiling 2 source files to C:\EJB\EjbComponent\build\classes
warning: [options] bootstrap class path not set in conjunction with -source 1.6
Note: C:\EJB\EjbComponent\src\java\com\tutorialspoint\stateless
\LibraryPersistentBean.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 warning
compile:
library-inclusion-in-archive:
Created dir: C:\EJB\EjbComponent\dist
Building jar: C:\EJB\EjbComponent\dist\EjbComponent.jar
dist:
BUILD SUCCESSFUL (total time: 3 seconds)

启动应用程序服务器

• 在“服务”窗口中的“服务器”下选择 JBoss 应用程序服务器。
• 右键单击它以打开上下文菜单。
• 选择开始。

您将在 NetBeans 中看到以下输出，即 JBoss 应用程序服务器下的输出。

Calling C:\jboss-5.1.0.GA\bin\run.conf.bat
=========================================================================
 
   JBoss Bootstrap Environment
 
   JBOSS_HOME: C:\jboss-5.1.0.GA
 
   JAVA: C:\Program Files (x86)\Java\jdk1.6.0_21\bin\java
 
   JAVA_OPTS: -Dprogram.name=run.bat -Xms128m -Xmx512m -server
 
   CLASSPATH: C:\jboss-5.1.0.GA\bin\run.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

部署项目

• 在 Project Explorer 窗口中选择 EjbComponent 项目。
• 右键单击它以打开上下文菜单。
• 选择部署。

您将在 NetBeans 控制台输出中看到以下输出。

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:\EJB\EjbComponent\dist\EjbComponent.jar
dist-directory-deploy:
pre-run-deploy:
Checking data source definitions for missing JDBC drivers...
Distributing C:\EJB\EjbComponent\dist\EjbComponent.jar to [org.jboss.deployment.spi.LocalhostTarget@1e4f84ee]
Deploying C:\EJB\EjbComponent\dist\EjbComponent.jar
Application Deployed
Operation start started
Operation start completed
post-run-deploy:
run-deploy:
run:
BUILD SUCCESSFUL (total time: 2 seconds)

JBoss应用服务器日志输出

16:30:00,963 INFO  [DeployHandler] Begin start, [EjbComponent.jar]
...
16:30:01,233 INFO  [Ejb3DependenciesDeployer] Encountered deployment AbstractVFSDeploymentContext@12038795{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 
AbstractBeanMetaData@5497cb{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

创建客户端来访问EJB

• 在 NetBeans IDE 中，选择“文件”>“新建项目”>。

• 在类别Java下选择项目类型，项目类型为Java 应用程序。单击下一步 > 按钮

• 输入项目名称和位置。单击完成 >按钮。我们选择名称为 EjbTester。

• 右键单击项目资源管理器窗口中的项目名称。选择属性。

• 使用编译选项卡中的“添加项目”按钮添加之前在库下创建的 EJB 组件项目。

• 使用编译选项卡中的“添加 jar/文件夹”按钮添加 jboss 库。Jboss 库可以位于<jboss 安装文件夹>> 客户端文件夹。

在 EjbTester 项目下创建 jndi.properties。

jndi.属性

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

在其下创建包 com.tutorialspoint.test 和 EJBTester.java 类。

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 \n1. Add Book\n2. Exit \nEnter 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());
         }
      }
   }  
}

运行客户端访问EJB

在项目资源管理器中找到 EJBTester.java。右键单击 EJBTester 类并选择运行文件。

在 Netbeans 控制台中验证以下输出。

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

在接下来的章节中，我们将介绍这个完整的 EJB 应用程序的多个方面。