使用EJB命名异常

时间：2014-04-12 03:59:32

标签： java ejb javabeans

我正在尝试按照在线教程进行操作，虽然我确信本教程的作者知道他们在做什么，但我仍然会在执行时遇到异常。

远程接口

package com.tutorialspoint.stateless;

import java.util.List;
import javax.ejb.Remote;

@Remote
public interface LibrarySessionBeanRemote {
   void addBook(String bookName);
   List getBooks();
}

无状态EJB 

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;
   }
}

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

测试

package com.tutorialspoint.test;

import com.tutorialspoint.stateful.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();
               Book book = new Book();
               book.setName(bookName);
               libraryBean.addBook(book);          
            } else if (choice == 2) {
               break;
            }
         }

         List<Book> booksList = libraryBean.getBooks();

         System.out.println("Book(s) entered so far: " + booksList.size());
         int i = 0;
         for (Book book:booksList) {
            System.out.println((i+1)+". " + book.getName());
            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());
         }
      }
   }
}

我得到了这个例外：

javax.naming.NoInitialContextException: Cannot instantiate class: org.jnp.interfaces.NamingContextFactory [Root exception is java.lang.ClassNotFoundException: org.jnp.interfaces.NamingContextFactory]
null
    at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:674)
    at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:313)
    at javax.naming.InitialContext.init(InitialContext.java:244)
    at javax.naming.InitialContext.<init>(InitialContext.java:216)
    at test.EJBTester.<init>(EJBTester.java:33)
    at test.EJBTester.main(EJBTester.java:42)
Caused by: java.lang.ClassNotFoundException: org.jnp.interfaces.NamingContextFactory
    at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:340)
    at com.sun.naming.internal.VersionHelper12.loadClass(VersionHelper12.java:72)
    at com.sun.naming.internal.VersionHelper12.loadClass(VersionHelper12.java:61)
    at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:672)
    ... 5 more
java.lang.NullPointerException
    at test.EJBTester.testStatelessEjb(EJBTester.java:56)
    at test.EJBTester.main(EJBTester.java:44)

非常感谢您的帮助！ d

2 个答案:

答案 0 :(得分：0)

当您进行远程EJB调用时，基本上您需要完成（在客户端）以下几点：

  1. 向客户端CLASSPATH添加必要的依赖项，这是：add 远程接口类和服务器客户端类。
  2. 使用正确的属性实例化InitialConetxt。
  3. 并提供正确的查找名称。

    4. 堆栈跟踪显示：

    java.lang.ClassNotFoundException: org.jnp.interfaces.NamingContextFactory,

    表示问题可能是客户端服务器类不在类路径中。

    正如教程所示，解决方案是：

      

    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＆gt;客户端文件夹。

答案 1 :(得分：0)

当我查看代码时，认为在客户端中解决JNDI查找将解决问题:)这是主要问题....在客户端代码中读取我的注释...但随着我的发现，我更加意识到这是复制从其他培训中粘贴而没有Book JavaBean等等。。。因此最终重写了整个内容...

复制代码一切顺利..... 重新启动部署EJBS的服务器。运行客户端 client .jar [classfish中的gf-client.jar]。

界面 

package com.au.ejbs;

import java.util.List;

public interface LibraryI {
    void addBook(Book bookName);

    List<Book> getBooks();

    void clearShelf();
}

实施

package com.au.ejbs;

import java.util.ArrayList;
import java.util.List;
import javax.ejb.Remote;
import javax.ejb.Stateless;
@Remote
@Stateless
public class Library implements LibraryI {

    private List<Book> bookShelf = new ArrayList<Book>();

    @Override
    public void addBook(Book bookName) {
        bookShelf.add(bookName);
    }

    @Override
    public List<Book> getBooks() {
        return bookShelf;
    }

    public void clearShelf(){
        if(!bookShelf.isEmpty())
        bookShelf.clear();
    }
}

package com.au.ejbs;


import javax.ejb.Remote;
import java.io.Serializable;
import java.util.StringJoiner;

@Remote
public class Book implements Serializable {
    private String bookName;

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    @Override
    public String toString() {
        return new StringJoiner(", ", Book.class.getSimpleName() + "[", "]")
                .add("bookName='" + bookName + "'")
                .toString();
    }

}

客户

package com.au.clients;

import com.au.ejbs.Book;
import com.au.ejbs.Library;
import com.au.ejbs.LibraryI;

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 LibraryT {

    BufferedReader brConsoleReader = null;
    Properties props;
    InitialContext ctx;

    {
        props = new Properties();
        try {
            props.load(new FileInputStream("config.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) {

        LibraryT LibraryT = new LibraryT();

        LibraryT.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() {
        List<Book> booksList = null;
        LibraryI libraryBean = null;
        try {
            int choice = 1;

            // LibraryI libraryBean = (LibraryI)ctx.lookup("LibrarySessionBean/remote");
            libraryBean = (LibraryI) ctx.lookup("java:global/ejb3_2_ear_exploded/ejb/Library");//Portable should work on jboss and any container , works on glassfish
              //portable syntax java:global/[ ear name]/[module name normally the jar name in my case ejb.jar within the ear, ejb3_2_ear_exploded]/Class Name of EJB impl

            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();
                    Book book = new Book();
                    book.setBookName(bookName);
                    libraryBean.addBook(book);
                } else if (choice == 2) {
                    break;
                }
            }

            booksList = libraryBean.getBooks();

            System.out.println("Book(s) entered so far: " + booksList.size());
            int i = 0;
            for (Book book : booksList) {
                System.out.println((i + 1) + ". " + book.getBookName());
                i++;
            }
            // LibraryI libraryBean1 = (LibraryI)ctx.lookup("LibrarySessionBean/remote");
            LibraryI libraryBean1 = (LibraryI) ctx.lookup("java:global/ejb3_2_ear_exploded/ejb/Library");//Portable should work on jboss and any container , works on glassfish
            List<Book> 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 (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();
                    libraryBean.clearShelf();
                }


            } catch (IOException ex) {
                System.out.println(ex.getMessage());
            }
        }
    }
}

config.properties

// JNDI特定于玻璃鱼，您可以将其用于jboss java.naming.factory.initial = com.sun.enterprise.naming.SerialInitContextFactory java.naming.provider.url =远程：// localhost：4447

输出 

**********************
Welcome to Book Store
**********************
Options 
1. Add Book
2. Exit 
Enter Choice: 1
Enter book name: Road Ahead
**********************
Welcome to Book Store
**********************
Options 
1. Add Book
2. Exit 
Enter Choice: 1
Enter book name: Living the Past
**********************
Welcome to Book Store
**********************
Options 
1. Add Book
2. Exit 
Enter Choice: 1
Enter book name: Enjoy the Present
**********************
Welcome to Book Store
**********************
Options 
1. Add Book
2. Exit 
Enter Choice: 2
Book(s) entered so far: 3
1. Road Ahead
2. Living the Past
3. Enjoy the Present
***Using second lookup to get library stateless object***
Book(s) entered so far: 3
1. Book[bookName='Road Ahead']
2. Book[bookName='Living the Past']
3. Book[bookName='Enjoy the Present']

Process finished with exit code 0
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