bookbean.java

第一步：将MyBookApp目录复制到C:下。 第二步：将book.mdb复制到C:下。 第三步：配制ODBC数据源

/*
 * BookBean.java
 *
 * Created on 2003年5月12日, 下午10:11
 */

/**
 *
 * @author  administrator
 */
import java.sql.*;
import javax.sql.*;
import java.util.*;
import java.math.*;
import javax.ejb.*;
import javax.naming.*;
import javax.rmi.PortableRemoteObject;
import java.rmi.RemoteException;

public class BookBean implements EntityBean{
    //entity variables
    private String id;
    private String bookName;
    private String bookAuthor;
    private String bookPublisher;
    private String bookDate;
    private String bookNote;
    
    //other variables
    private EntityContext context;
    private Connection con;
    private String dbName = "java:comp/env/jdbc/book";
    
    //entity bean's method
    public void ejbActivate() throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
        id = (String)context.getPrimaryKey();
    }
    
    public void ejbLoad() throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
        try {
         loadRow();
       } catch (Exception ex) {
           throw new EJBException("ejbLoad: " + 
              ex.getMessage());
       }
    }
    
    public void ejbPassivate() throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
        id = null;
    }
    
    //we don't use this method for this programm
    public void ejbRemove() throws javax.ejb.RemoveException, javax.ejb.EJBException, java.rmi.RemoteException 
    {
    }
    
    public void ejbStore() throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
        try {
         storeRow();
       } catch (Exception ex) {
           throw new EJBException("ejbStore: " + 
              ex.getMessage());
       }
    }
    
    public void setEntityContext(javax.ejb.EntityContext entityContext) throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
      this.context = entityContext;
      try {
         makeConnection();
      } catch (Exception ex) {
          throw new EJBException("Unable to connect to database. " +
             ex.getMessage());
      }
    }
    
    public void unsetEntityContext() throws javax.ejb.EJBException, java.rmi.RemoteException 
    {
        try {
         con.close();
      } catch (SQLException ex) {
          throw new EJBException("unsetEntityContext: " + ex.getMessage());
      }
    }
    
  
    //home method
    //we don't use this method for this programm
    public String ejbCreate() throws CreateException 
    {
        return "1";
    }
    
    public void ejbPostCreate() 
    {
    }
    
    public String ejbFindByPrimaryKey(String primaryKey) throws FinderException 
    {
      boolean result;
      try {
         result = selectByPrimaryKey(primaryKey);
       } catch (Exception ex) {
           throw new EJBException("ejbFindByPrimaryKey: " + 
              ex.getMessage());
       }
      if (result) {
         return primaryKey;
      }
      else {
         throw new ObjectNotFoundException
            ("Row for id " + primaryKey + " not found.");
      }
    }
    
    public Collection ejbFindByBookName(String bookName) throws FinderException 
    {
      Collection result;

      try {
         result = selectByBookName(bookName);
       } catch (Exception ex) {
           throw new EJBException("ejbFindByBookName " + 
              ex.getMessage());
       }
       return result;
    }
    
    //business method
    public String getBookName() throws RemoteException
    {
        return bookName;
    }
   
   
   public String getBookAuthor() throws RemoteException
   {
       return bookAuthor;
   }
   
 
   public String getBookPublisher() throws RemoteException
   {
       return bookPublisher;
   }
   
  
   public String getBookDate() throws RemoteException
   {
       return bookDate;
   }
   
  
   public String getBookNote() throws RemoteException
   {
       return bookNote;
   }
    
    //========================helper functions========================
    private void makeConnection() throws NamingException, SQLException 
    {
      InitialContext ic = new InitialContext();
      DataSource ds = (DataSource) ic.lookup(dbName);
      con =  ds.getConnection();
    }
    
    private boolean selectByPrimaryKey(String primaryKey) throws SQLException 
    {

      String selectStatement =
            "select id " +
            "from book where id = ? ";
      PreparedStatement prepStmt =con.prepareStatement(selectStatement);
      prepStmt.setInt(1, Integer.parseInt(primaryKey));

      ResultSet rs = prepStmt.executeQuery();
      boolean result = rs.next();
      prepStmt.close();
      return result;
    }
    
    private Collection selectByBookName(String bookName) throws SQLException 
    {

      String selectStatement =
            "select id " +
            "from book where book_name like ? ";
      PreparedStatement prepStmt = 
            con.prepareStatement(selectStatement);

      prepStmt.setString(1, "%"+bookName+"%");
      ResultSet rs = prepStmt.executeQuery();
      ArrayList a = new ArrayList();

      while (rs.next()) {
         String id = rs.getString(1);
         a.add(id);
      }

      prepStmt.close();
      return a;
    }
    
    private void loadRow() throws SQLException {

      String selectStatement =
            "select book_name,book_author,book_publisher,book_date,book_note " +
            "from book where id = ? ";
      PreparedStatement prepStmt = 
            con.prepareStatement(selectStatement);

      prepStmt.setInt(1, Integer.parseInt(this.id));

      ResultSet rs = prepStmt.executeQuery();

      if (rs.next()) {
         this.bookName = rs.getString(1);
         this.bookAuthor = rs.getString(2);
         this.bookPublisher = rs.getString(3);
         this.bookDate = rs.getString(4);
         this.bookNote = rs.getString(5);
         prepStmt.close();
      }
      else {
         prepStmt.close();
         throw new NoSuchEntityException("Row for id " + id +
            " not found in database.");
      }
   }


   private void storeRow() throws SQLException 
   {
      String updateStatement =
            "update book set book_name =  ? ," +
            "book_author = ? , book_publisher = ? ," +
            "book_date = ? , book_note = ? " +
            "where id = ?";
      PreparedStatement prepStmt = 
            con.prepareStatement(updateStatement);

      prepStmt.setString(1, bookName);
      prepStmt.setString(2, bookAuthor);
      prepStmt.setString(3, bookPublisher);
      prepStmt.setString(4, bookDate);
      prepStmt.setString(5, bookNote);
      prepStmt.setInt(6, Integer.parseInt(this.id));
      int rowCount = prepStmt.executeUpdate();
      prepStmt.close();

      if (rowCount == 0) {
         throw new EJBException("Storing row for id " + id + " failed.");
      }
   }
    
    
    
}