在eclipse中postgreSQL的访问有关问题

package jp.bcat;import java.sql.*;import java.util.Vector;public class DatabaseBookCatalog extends BookCatalog {    Connection connection;    static final String DATABASE_URL = "jdbc:postgresql://127.0.0.1/bcat";    static final String DATABASE_USER = "bcat";    static final String DATABASE_PASSWORD = "secret";    public DatabaseBookCatalog() {        connect();    }    protected boolean connect() {        try {            if (connection != null) {                if (connection.getWarnings() == null)                    return true;                disconnect();            }            DriverManager.registerDriver(new org.postgresql.Driver());            connection = DriverManager.getConnection(DATABASE_URL, DATABASE_USER, DATABASE_PASSWORD);            if (connection.getWarnings() == null)                return true;            disconnect();        } catch (Exception ex) {            ex.printStackTrace();        }        return false;    }    protected void disconnect() {        if (connection != null) {            try {                connection.close();            } catch (Exception ex) {                ex.printStackTrace();            }            connection = null;        }    }    public Book getBook(String bookId) {        Book book = null;        try {            connect();            PreparedStatement statement = connection.prepareStatement("SELECT * FROM bookcatalog WHERE bookid = ?");            statement.setString(1, bookId);            ResultSet result = statement.executeQuery();            if (result.next())                 book = createBook(result);            statement.close();        } catch (SQLException ex) {            ex.printStackTrace();        }        return book;    }    public Book[] getBooks() {        Book [] bookArray = null;        try {            connect();            Statement statement = connection.createStatement();            ResultSet result = statement.executeQuery("SELECT * FROM bookcatalog ORDER BY datacreateddate DESC");            bookArray = createBooks(result);            statement.close();        } catch (SQLException ex) {            ex.printStackTrace();        }        return bookArray;    }    public synchronized Book addBook(Book book) {        try {            connect();            String bookId = book.getBookId();            if (bookId == null || bookId.length() == 0 || getBook(bookId) != null)                bookId = createUniqueBookId();            PreparedStatement statement = connection.prepareStatement("INSERT INTO bookcatalog (bookid,title,author,translator,publisher,publicationdate,code,status,keyword,memo,datacreator,datacreateddate) VALUES (?,?,?,?,?,to_date(?,'YYYY-MM-DD'),?,?,?,?,?,to_timestamp(?,'YYYY-MM-DD HH24:MI:SS'))");            statement.setString(1, bookId);            statement.setString(2, book.getTitle());            statement.setString(3, book.getAuthor());            statement.setString(4, book.getTranslator());            statement.setString(5, book.getPublisher());            statement.setString(6, book.getPublicationDate());            statement.setString(7, book.getCode());            statement.setString(8, book.getStatus());            statement.setString(9, book.getKeyword());            statement.setString(10, book.getMemo());            statement.setString(11, book.getDataCreator());            statement.setString(12, book.getDataCreatedDate());            int result = statement.executeUpdate();            statement.close();            return getBook(bookId);        } catch (SQLException ex) {            ex.printStackTrace();        }        return null;    }    public void deleteBook(String bookId) {        try {            connect();            PreparedStatement statement = connection.prepareStatement("DELETE FROM bookcatalog WHERE bookid = ?");            statement.setString(1, bookId);            int result = statement.executeUpdate();            statement.close();        } catch (SQLException ex) {            ex.printStackTrace();        }    }       public Book[] searchBooks(String word) {        Book [] bookArray = null;        try {            connect();            PreparedStatement statement = connection.prepareStatement("SELECT * FROM bookcatalog WHERE bookid LIKE ? OR UPPER(title) LIKE ? OR UPPER(author) LIKE ? OR UPPER(translator) LIKE ? OR UPPER(publisher) LIKE ? OR UPPER(code) LIKE ? OR UPPER(status) LIKE ? OR UPPER(keyword) LIKE ? OR UPPER(memo) LIKE ? OR UPPER(datacreator) LIKE ? ORDER BY datacreateddate DESC");            String pattern = "%" + word.toUpperCase() + "%";            for (int i = 1; i <= 10; i++)                    statement.setString(i, pattern);            ResultSet result = statement.executeQuery();            bookArray = createBooks(result);            statement.close();        } catch (SQLException ex) {            ex.printStackTrace();        }        return bookArray;    }    protected Book createBook(ResultSet result) throws SQLException {        Book book = new Book();        book.setBookId(result.getString("bookid"));        book.setTitle(result.getString("title"));        book.setAuthor(result.getString("author"));        book.setTranslator(result.getString("translator"));        book.setPublicationDate(result.getTimestamp("publicationdate").toString().substring(0,10));        book.setPublisher(result.getString("publisher"));        book.setCode(result.getString("code"));        book.setStatus(result.getString("status"));        book.setKeyword(result.getString("keyword"));        book.setMemo(result.getString("memo"));        book.setDataCreatedDate(result.getTimestamp("datacreateddate").toString().substring(0,16));        book.setDataCreator(result.getString("datacreator"));        return book;    }    protected Book [] createBooks(ResultSet result) throws SQLException {        Vector books = new Vector();        while (result.next())             books.add(createBook(result));        Book [] bookArray = new Book[books.size()];        books.toArray(bookArray);        return bookArray;    }}