J2EE Tutorial 實戰：從零建立簡單 Stateless Session Bean (Converter 應用完整步驟)

環境準備

1. 下載範例碼：j2eetutorial/examples/src/ejb/converter (Sun 下載頁)
2. 安裝 Ant (Apache Ant)
3. 設定環境變數：JAVA_HOME, J2EE_HOME, ANT_HOME, PATH 包含三者 bin 目錄
4. 啟動 J2EE Server：j2ee -verbose (停止：j2ee -stop)
5. 啟動 DeployTool (GUI)：deploytool

建立 J2EE 應用程式

• DeployTool：File → New Application
• 目錄選 j2eetutorial/examples/src/ejb/converter
• 檔案名 ConverterApp.ear

建立 Enterprise Bean (ConverterEJB)

三大組件

1. Remote Interface：Converter.java

   
   public interface Converter extends EJBObject {
       BigDecimal dollarToYen(BigDecimal dollars) throws RemoteException;
       BigDecimal yenToEuro(BigDecimal yen) throws RemoteException;
   }
   

2. Home Interface：ConverterHome.java

   
   public interface ConverterHome extends EJBHome {
       Converter create() throws RemoteException, CreateException;
   }
   

3. Bean Class：ConverterBean.java (Stateless)

   
   public class ConverterBean implements SessionBean {
       BigDecimal yenRate = new BigDecimal("121.6000");
       BigDecimal euroRate = new BigDecimal("0.0077");
       public BigDecimal dollarToYen(BigDecimal dollars) {
           return dollars.multiply(yenRate).setScale(2, BigDecimal.ROUND_UP);
       }
       public BigDecimal yenToEuro(BigDecimal yen) {
           return yen.multiply(euroRate).setScale(2, BigDecimal.ROUND_UP);
       }
       // ejbCreate, ejbRemove, ejbActivate, ejbPassivate, setSessionContext 皆為空實作
   }
   

編譯與打包

1. 命令列：ant converter (輸出至 build/ejb/converter)
2. DeployTool：File → New Enterprise Bean → 建立 JAR (ConverterJAR) → 加入三個類別
3. Bean Type：Session, Stateless, Class: ConverterBean, Name: ConverterEJB
4. Remote Home: ConverterHome, Remote: Converter

建立應用程式客戶端

原始碼：ConverterClient.java

public class ConverterClient {
    public static void main(String[] args) {
        try {
            Context initial = new InitialContext();
            Object objref = initial.lookup("java:comp/env/ejb/SimpleConverter");
            ConverterHome home = (ConverterHome) PortableRemoteObject.narrow(objref, ConverterHome.class);
            Converter currencyConverter = home.create();
            BigDecimal param = new BigDecimal("100.00");
            BigDecimal amount = currencyConverter.dollarToYen(param);
            System.out.println(amount); // 12160.00
            amount = currencyConverter.yenToEuro(param);
            System.out.println(amount); // 0.77
        } catch (Exception ex) { ex.printStackTrace(); }
    }
}

打包客戶端

• DeployTool：New Application Client → 加入 ConverterClient.class
• Main Class: ConverterClient, Callback Handler: container-managed
• EJB Refs：Coded Name ejb/SimpleConverter, Type Session, Interface Remote, Home ConverterHome, Remote Converter

建立 Web Client (JSP)

• index.jsp (無需編譯)
• DeployTool：New Web Component → New WAR (ConverterWAR) → 加入 index.jsp
• EJB Refs：Coded Name ejb/TheConverter (其他同客戶端)

指定 JNDI 名稱

• 選擇 ConverterApp → JNDI Names 標籤 → 全部輸入 MyConverter

部署與執行

1. Tools → Deploy → Return Client JAR → 指定輸出路徑
2. 確認 JNDI Name → WAR Context Root: converter

執行應用程式客戶端

cd j2eetutorial/examples/src/ejb/converter
set APPCPATH=ConverterAppClient.jar
runclient -client ConverterApp.ear -name ConverterClient -textauth
# user: guest / pass: guest123
# 輸出: 12160.00 / 0.77

執行 Web Client

https://:8000/converter