Bean类实现(Part31) public void withdraw( String accountName int amount) throws Banker Failure Exception try System. out printIn (" Entry withdraw"; conn= ds. getconnectiono Statement stmt= conn. createStatemento; Resultset res stmt execute Query( SELECT FROM accounts WHERE accountname = accountName+) //从账户上减去相应的金额 int new Balance if(res nexto if(amount res getInt( balance")) throw new BankerFailure Exception ("no enough balance "); newBalance res getInt("balance")-amount; tmt. execute ( "UPDATE accounts sET balance =" new Balance ); elset throw new Banker Failure Exception(" invalid accountName ) conn.close System. out. printIn (accountName+s balance changed to"+ new Balance); System. out println("pushing cash.. ) ∥操纵取款机为用户吐出现金 push Cash(amount) 数据库操作 System. out. printin( withdraw finished succes Scatch(sQLException er 首先利用数据源获取数 throw new Banker FailureException( "operatior据库连接,操作账户记录,从当 前账户上扣除所取金额Bean类实现(Part 3_1) public void withdraw(String accountName, int amount) throws BankerFailureException{ try{ System.out.println("Entry withdraw"); conn = ds.getConnection(); Statement stmt = conn.createStatement(); ResultSet res = stmt.executeQuery( "SELECT * FROM accounts WHERE accountname = '" + accountName + "'"); //从账户上减去相应的金额 int newBalance; if(res.next()){ if(amount > res.getInt("balance")){ throw new BankerFailureException("no enough balance"); } newBalance = res.getInt("balance") - amount; stmt.execute("UPDATE accounts SET balance = " + newBalance); } else{ throw new BankerFailureException("invalid accountName"); } conn.close(); System.out.println(accountName + "'s balance changed to " + newBalance); System.out.println("pushing cash..."); //操纵取款机为用户吐出现金 pushCash(amount); System.out.println("withdraw finished successfully"); }catch(SQLException e){ throw new BankerFailureException("operation failed"); } } 数据库操作： 首先利用数据源获取数 据库连接，操作账户记录，从当 前账户上扣除所取金额