bookdbejbimpl.java

J2EE导学

/*
 *
 * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */


package database;

import java.util.*;
import java.sql.*;
import javax.sql.*;
import javax.naming.*;
import javax.ejb.*;
import exception.*;

public class BookDBEJBImpl implements SessionBean {
   		
   private ArrayList books = null;
   private Connection con = null;
   private String dbName = "java:comp/env/jdbc/BookDB";

   // implementation of create and remove remote methods

   public void ejbCreate() throws CreateException {
    try  {               
         InitialContext ic = new InitialContext();
         DataSource ds = (DataSource) ic.lookup(dbName);
         con =  ds.getConnection();     
   	} catch (Exception ex) {
         throw new CreateException("Couldn't create bean: " + ex.getMessage());
      }
       books = new ArrayList();
   }

   public void ejbRemove() throws EJBException {
     try {
         con.close();
      } catch (SQLException ex) {
          throw new EJBException("unsetEntityContext: " + ex.getMessage());
      }
      con = null;
      books = null;
   }
   
   public BookDBEJBImpl() {}
   public void ejbActivate() {}
   public void ejbPassivate() {}
   public void setSessionContext(SessionContext sc) {}

    // remote methods
 
    public int getNumberOfBooks() throws BooksNotFoundException {
            books = new ArrayList();
                try {

                         String selectStatement =
                                           "select * " + 
                                           "from books";
                         PreparedStatement prepStmt = 
                                           con.prepareStatement(selectStatement);
                         ResultSet rs = prepStmt.executeQuery();



                         while (rs.next()) {
                              BookDetails bd = new BookDetails(rs.getString(1), rs.getString(2), rs.getString(3), rs.getString(4), 
                                  rs.getFloat(5), rs.getInt(6), rs.getString(7));
                                  books.add(bd);
                         }
                         prepStmt.close();
                } catch (SQLException ex) {
                   throw new BooksNotFoundException("Couldn't find books: " +  ex.getMessage());
                }
            return books.size();

    }
      
    public Collection getBooks() throws BooksNotFoundException {
      try {
      
            String selectStatement =
                        "select * " + 
                        "from books";
            PreparedStatement prepStmt = 
                        con.prepareStatement(selectStatement);
            ResultSet rs = prepStmt.executeQuery();
      
            books = new ArrayList();
      
            while (rs.next()) {
               BookDetails bd = new BookDetails(rs.getString(1), rs.getString(2), rs.getString(3), rs.getString(4), 
                  rs.getFloat(5), rs.getInt(6), rs.getString(7));
               books.add(bd);
            }
            prepStmt.close();
      } catch (SQLException ex) {
         throw new BooksNotFoundException("Couldn't find books: " +  ex.getMessage());
      }
      
      Collections.sort(books);
      return books;
   }
      
    public BookDetails getBookDetails(String bookId) throws BookNotFoundException {
      try {
            String selectStatement =
                        "select * " +
                        "from books where id = ? ";
            PreparedStatement prepStmt = 
                        con.prepareStatement(selectStatement);

            prepStmt.setString(1, bookId);

            ResultSet rs = prepStmt.executeQuery();

            if (rs.next()) {
               BookDetails bd = new BookDetails(rs.getString(1), rs.getString(2), rs.getString(3), rs.getString(4), 
                  rs.getFloat(5), rs.getInt(6), rs.getString(7));
               prepStmt.close();
               return bd;

            }
            else {					
               prepStmt.close();
                      throw new BookNotFoundException("Couldn't find book: " + bookId);
            }
      } catch (SQLException ex) {
           throw new BookNotFoundException("Couldn't find book: " + bookId + ex.getMessage());
      }
   }
}