Programming Design Notes

首先制作 EJB 部份。制作一個 MessageRemote 的介面，然後再實作這個介面。
** EJB 3.1 不再需要 Local 的介面 **

MessageRemote:

package com.blogspot.lawpronotes.ejb;
import javax.ejb.Remote;

@Remote
public interface MessageRemote {
    public String sayHello();
}

Message:

package com.blogspot.lawpronotes.ejb;

import javax.ejb.EJB;
import javax.ejb.LocalBean;
import javax.ejb.Stateless;

/**
 * Session Bean implementation class Message
 */
@LocalBean
@Stateless
@EJB(name="java:global/HelloWorldEJB/Message", beanInterface=MessageRemote.class)
public class Message implements MessageRemote {

    /**
     * Default constructor. 
     */
    public Message() {
        // TODO Auto-generated constructor stub
    }

    @Override
    public String sayHello() {
        // TODO Auto-generated method stub
        return "Hello World";
    }
    
}

現在可以將 EJB Project 放到 GlassFish 上，然後制作一個 JAR 並將 EJB 的 Remote 介面放到 JAR 內，緊記不要連同實作的 Class 放到 JAR 內，不然會發生錯誤。

現在制作 Servlet 部份。將剛才制作好的 JAR 放到 WEB-INF/lib 內。
新增一個 IndexServlet ，複製以下程式碼並貼上。

package com.blogspot.lawpronotes.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Properties;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.blogspot.lawpronotes.ejb.MessageRemote;

/**
 * Servlet implementation class IndexServlet
 */
@WebServlet(name = "Index", urlPatterns = { "/index" })
public class IndexServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    private Properties properties;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public IndexServlet() {
        super();
        // TODO Auto-generated constructor stub
        properties = new Properties();
        properties.put("java.naming.factory.initial",
                "com.sun.enterprise.naming.impl.SerialInitContextFactory");
        properties.put("java.naming.factory.url.pkgs",
                "com.sun.enterprise.naming");
        properties.put("java.naming.factory.state",
                "com.sun.corba.ee.impl.presentation.rmi.JNDIStateFactoryImpl");
        properties.setProperty("org.omg.CORBA.ORBInitialHost", "localhost");
        properties.setProperty("org.omg.CORBA.ORBInitialPort", "3700");
    }

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        PrintWriter out = response.getWriter();
        try {
            InitialContext context = new InitialContext(properties);
            Object obj = context.lookup("java:global/HelloWorldEJB/Message");
            MessageRemote message = (MessageRemote) PortableRemoteObject
                    .narrow(obj, MessageRemote.class);
            out.print(message.sayHello());
        } catch (NamingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            out.print(e.toString());
        }
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }
}

web.xml 設定如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
 id="WebApp_ID" version="2.5">
 <display-name>HelloWorldWAR</display-name>
 <welcome-file-list>
  <welcome-file>index</welcome-file>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
 </welcome-file-list>
</web-app>

現在將 WAR Project 放上 GlassFish。再打開 IndexServlet 應該會出現 Hello World 字樣。

單機 Java 應用程式也是差不多的做法，但一有點要注意的是要將 GlassFish 的 appserv-rt.jar 加到單機 Java 應用程式下，才能正確地用到 Remote EJB。當然 EJB 的 JAR 也是必需的。
** appserv-rt.jar 在 GlassFish 的 lib 資料夾內 **

Main:

package com.blogspot.lawpronotes.app;

import java.util.Properties;

import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.rmi.PortableRemoteObject;

import com.blogspot.lawpronotes.ejb.MessageRemote;

public class Main {
    public static void main(String[] args) throws NamingException{
        Properties properties = new Properties();
        properties.put("java.naming.factory.initial", "com.sun.enterprise.naming.impl.SerialInitContextFactory");
        properties.put("java.naming.factory.url.pkgs", "com.sun.enterprise.naming");
        properties.put("java.naming.factory.state", "com.sun.corba.ee.impl.presentation.rmi.JNDIStateFactoryImpl");
        properties.setProperty("org.omg.CORBA.ORBInitialHost", "localhost");
        properties.setProperty("org.omg.CORBA.ORBInitialPort", "3700");
        InitialContext context = new InitialContext(properties);
        Object obj = context.lookup("java:global/HelloWorldEJB/Message");
        MessageRemote message = (MessageRemote)PortableRemoteObject.narrow(obj, MessageRemote.class);
        System.out.println(message.sayHello());
    }
}

在 Console 會看見 Hello World 字樣。

Eclipse 範例在這裡下載: RemoteEJB.zip

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