一个图书管理系统

				/*				 * 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.");				      }				   }				    				    				    				}