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EJB創建應用

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要創建一個簡單的EJB模塊，我們這裡使用NetBeans“New project”向導。在下麵的例子中，我們將創建一個名為“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.

New Project Wizard step 1

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

New Project Wizard step 2

輸入項目的名稱和位置。點擊Next>按鈕。你會看到以下的畫麵。

New Project Wizard step 3

選擇服務器為JBoss應用服務器。單擊“Finish”按鈕。你會看到以下由NetBeans創建的項目。

Project explorer

創建一個簡單的EJB

要創建一個簡單的EJB，我們將使用NetBeans“New”向導。在下麵的例子中，我們將在EjbComponent項目下創建一個無狀態EJB類名為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向導。

New Session Bean Wizard

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，我們要一個基於控製台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更名為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

  • 在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控製台輸出，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)

啟動應用程序服務器

  • 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。

你會看到下麵的輸出在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

  • 在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控製台輸出，你會看到下麵的輸出。

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 [org.jboss.deployment.spi.LocalhostTarget@1e4f84ee]
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 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

創建客戶端訪問EJB

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

  • 類彆下選擇項目類型為Java，項目類型為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。我們選擇名為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類在下麵。

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

在project explorer中找到EJBTester.java。右鍵點擊上EJBTester類，並選擇“run file”。

在Netbeans控製台驗證以下輸出。

run:
**********************
Welcome to Book Store
**********************
Options 
1. Add Book
2. Exit 
Enter Choice: 1
Enter book name: Learn Java
**********************
Welcome to Book Store
**********************
Options 
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)

在下麵的章節中，我們將討論這個完整的EJB的多個層麵應用程序。



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