【正文】 tion getItems() {return ()。}protected void finalize() throws Throwable {()。}public synchronized int getNumberOfItems() {return numberOfItems。}public synchronized double getTotal() {double amount = 。for(Iterator i = getItems().iterator()。 ()。 ) {ShopCarItem item = (ShopCarItem) ()。BookDetail bookDetails = (BookDetail) ()。amount += () * ()。}return roundOff(amount)。}private double roundOff(double x) {long val = (x*100)。return val/。}public synchronized void clear() {()。numberOfItems = 0。}}3． 該網上書店系統(tǒng)是使用JDBC訪問MS Access數(shù)據(jù)庫。它是通過JDBCODBC驅動類型鏈接數(shù)據(jù)庫，所以需要先建立ODBC數(shù)據(jù)源。在這里ODBC數(shù)據(jù)源的名稱為BookShopDB。 ，包括數(shù)據(jù)庫鏈接、斷開數(shù)據(jù)庫鏈接、查詢數(shù)據(jù)庫紀錄和修改數(shù)據(jù)庫紀錄等方法。：getConnection方法實現(xiàn)數(shù)據(jù)庫鏈接；getBookDetail方法實現(xiàn)讀取書籍列表的詳細信息；buyBooks方法實現(xiàn)購買書籍；order方法實現(xiàn)了下訂單的處理。其代碼實現(xiàn)主要部分如下所示：package bookshop。import .*。import .*。public class BookDB {private ArrayList alBooks。private String dbUrl=jdbc:odbc:BookShopDB。private String orderId。public BookDB () throws Exception{()。}public Connection getConnection()throws Exception{return (dbUrl)。}public void closeConnection(Connection con){try{if(con!=null) ()。}catch(Exception e){()。}}public void closePrepStmt(PreparedStatement prepStmt){try{if(prepStmt!=null) ()。}catch(Exception e){()。}}public void closeResultSet(ResultSet rs){try{if(rs!=null) ()。}catch(Exception e){()。}}public int getNumberOfBooks() throws Exception {Connection con=null。PreparedStatement prepStmt=null。ResultSet rs=null。alBooks = new ArrayList()。try {con=getConnection()。String strSql = select * + from book。prepStmt = (strSql)。rs = ()。while (()) {BookDetail bd = new BookDetail((bookID), (title),(name),(time), (info),(pie),(price),(saleAmount))。(bd)。}}finally{closeResultSet(rs)。closePrepStmt(prepStmt)。closeConnection(con)。}return ()。}public Collection getBookList()throws Exception{Connection con=null。PreparedStatement prepStmt=null。ResultSet rs =null。alBooks = new ArrayList()。try {con=getConnection()。String strSql = select * + from book order by bookID。prepStmt = (strSql)。rs = ()。while (()) {BookDetail bd = new BookDetail((bookID), (title),(name),(time), (info),(pie),(price),(saleAmount))。(bd)。}}finally{closeResultSet(rs)。closePrepStmt(prepStmt)。closeConnection(con)。}(alBooks)。return alBooks。}public BookDetail getBookDetail(String bookId) throws Exception {Connection con=null。PreparedStatement prepStmt=null。ResultSet rs =null。try {con=getConnection()。(getConnection)。String strSql = select * from book where bookID = ? 。prepStmt = (strSql)。(1, bookId)。rs = ()。if (()) {BookDetail bd = new BookDetail((bookID), (title),(name),(time), (info),(pie),(price),(saleAmount))。()。return bd。}else {return null。}}finally{closeResultSet(rs)。closePrepStmt(prepStmt)。closeConnection(con)。}}public void buyBooks(ShopCar car)throws Exception {Connection con=null。Collection items = ()。Iterator i = ()。try {con=getConnection()。(false)。while (()) {ShopCarItem sci = (ShopCarItem)()。BookDetail bd = (BookDetail)()。String bookId=()。int quantity = ()。buyBook(bookId, quantity,con)。orderDetail(bd, quantity,con)。}()。(true)。} catch (Exception ex) {()。throw ex。}finally{closeConnection(con)。}}public void buyBook(String bookId, int quantity,Connection con) throws Exception {PreparedStatement prepStmt=null。ResultSet rs=null。try{String strSql = select * + from book where bookID = ? 。prepStmt = (strSql)。(1, bookId)。rs = ()。if (()) {()。strSql =update book set saleamount = saleamount + ? where bookID = ?。prepStmt = (strSql)。(1, quantity)。(2, bookId)。()。()。}}finally{closeResultSet(rs)。closePrepStmt(prepStmt)。}}public void orderDetail(BookDetail bd, int quantity,Connection con) throws Exception {PreparedStatement prepStmt=null。try{String strSql =insert into orderDetail(orderID,bookId,price,amount,moneys) + values(?,?,?,?,?)。prepStmt = (strSql)。(orderId)。(1,orderId)。(2, ())。(3, ())。(4, quantity)。(5, ()*quantity)。()。()。}finally{closePrepStmt(prepStmt)。}}public void order(Order order) throws Exception{Connection con=null。PreparedStatement prepStmt=null。try {con=getConnection()。String strSql = insert into orderList(orderID,status,allAmount,allMoney,name,phone,address,code,info) + values(?,?,?,?,?,?,?,?,?)。prepStmt = (strSql)。orderId=getNowTime()。(orderId)。(1, orderId)。(2, 有效)。(3, ())。(4, ())。(5, ())。(6, ())。(7, ())。(8, ())。(9, ())。()。}finally{closePrepStmt(prepStmt)。closeConnection(con)。}}public static String getNowTime() { ctime = new ()。String rTime = 。 cf = new (yyyyMMddHHmmss)。rTime = (ctime)。return rTime。}}4. 是用戶注冊信息的實體類，通過這個類將用戶輸入的注冊信息錄入數(shù)據(jù)庫中。其代碼如下：package bookshop。import .*。public class Linkdatabase { private Connection con=null。 private String sID = null。 private String sex = null。 private String sname = null。 private String spwd = null。 private String sbir = null。 private String sclass = null。 private String sadr = null。 private String stel = null。 private String s = null。 private String JDBC_DRIVER = 。 private String url = jdbc:odbc:bookDB。 public Linkdatabase(){ this(null)。 } //接收三個參數(shù)的構造方法并且調用空構造函數(shù)添加驅動 public Linkdatabase(String ID){ = ID。 //添加驅動的構造方法 try{ (JDBC_DRIVER)。 } catch(Exception e){ (類錯誤)。 (())。 } try{ con = (url,sa,)。 } catch(Exception e){ (連接錯誤)。 (())。 } } //返回帳號 public String getID(){ return 。 } //接收性別 public void setSex(String sex){ = sex。 } //接收姓名 public void setName(String name){ = name。 } //接收密碼 public void setPassword(String pwd){ = pwd。 } //接收出生年月 public void setBirthday(String bir){ = bir。 } //