数据库课程设计 银行数据库系统（模拟自动取款机）

package DB; import java.sql.ResultSet; import javax.swing.JOptionPane; public class DatabaseOperate { /** * @param args */ String sql, sql1; ResultSet rs = null; String account_number, branch_name, card_style, balance, customer_name, loan_number, card_number, branch_city, assets; String customer_street, customer_city, credit, amount, password; // 登录，根据用户输入卡号查询得到密码，并验证 public String[] login(String num) { DatabaseConn DB = new DatabaseConn(); this.card_number = num; String[] s = new String[4]; sql = "select * from login where card_number = " + Integer.parseInt(card_number) + " "; try { DB.OpenConn(); rs = DB.executeQuery(sql); if (rs.next()) { s[0] = rs.getString("customer_name"); s[1] = rs.getString("card_style"); s[2] = rs.getString("card_number"); s[3] = rs.getString("password"); } else s = null; } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return s; } // 查询存、取款账户相关信息 public String[] schbalance(String num) { DatabaseConn DB = new DatabaseConn(); this.card_number = num; String[] s = new String[6]; sql = "select * from depositor,account where (card_number = " + Integer.parseInt(card_number) + ") and depositor.account_number = account.account_number "; try { DB.OpenConn(); rs = DB.executeQuery(sql); if (rs.next()) { s[0] = rs.getString(1); // customer_name s[1] = rs.getString(2); // depositor.account_number s[2] = rs.getString(3); // card_number s[3] = rs.getString(4); // account.account_number s[4] = rs.getString(5); // branch_name s[5] = rs.getString(6); // balance } else s = null; } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return s; } // 查询贷款账户相关信息 public String[] schamount(String num) { DatabaseConn DB = new DatabaseConn(); this.card_number = num; String[] s = new String[6]; sql = "select * from borrower,loan where (card_number = " + Integer.parseInt(card_number) + ") and loan.loan_number = borrower.loan_number "; try { DB.OpenConn(); rs = DB.executeQuery(sql); if (rs.next()) { s[0] = rs.getString(1); // customer_name s[1] = rs.getString(2); // borrower.loan_number s[2] = rs.getString(3); // card_number s[3] = rs.getString(4); // loan.loan_number s[4] = rs.getString(5); // branch_name s[5] = rs.getString(6); // amount } else s = null; } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return s; } // 查询客户信用额度 public int schcredit(String name) { DatabaseConn DB = new DatabaseConn(); this.customer_name = name; int Credit = 0; sql = "select credit from customer where customer_name = '" + customer_name + "' "; try { DB.OpenConn(); rs = DB.executeQuery(sql); while (rs.next()) { Credit = rs.getInt(1); } } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return Credit; } // 存款，根据用户输的金额更新账户 public String[] deposit(String money, String num) { DatabaseConn DB = new DatabaseConn(); this.balance = money; this.card_number = num; String[] t = new String[6]; t = schbalance(card_number); double temp = Double.parseDouble(t[5].trim()) + Double.parseDouble(balance); sql = "update account set balance = " + temp + " where account_number = " + Integer.parseInt(t[1].trim()) + " "; try { DB.OpenConn(); DB.executeUpdate(sql); } catch (Exception e) { System.out.println(e); JOptionPane.showMessageDialog(null, "存款失败，请重新输入金额点击确定！", "错误", JOptionPane.ERROR_MESSAGE); } finally { DB.closeStmt(); DB.closeConn(); } return t; } // 取款 根据用户输的金额跟信用额度 更新账户 public String[] get(String money, String num) { DatabaseConn DB = new DatabaseConn(); this.card_number = num; this.balance = money; String[] t = new String[6]; t = schbalance(card_number); double temp = Double.parseDouble(t[5].trim()) - Double.parseDouble(balance); sql = "update account set balance = " + temp + " where account_number = " + Integer.parseInt(t[1].trim()) + " "; try { DB.OpenConn(); DB.executeUpdate(sql); } catch (Exception e) { System.out.println(e); JOptionPane.showMessageDialog(null, "取款失败，您取款金额过大请重新填写！", "错误", JOptionPane.ERROR_MESSAGE); } finally { DB.closeStmt(); DB.closeConn(); } return t; } // 贷款 ，根据用户输的金额跟信用额度、已经贷的金额 进行贷款 public void loan(String money, String num, String time, String rate) { DatabaseConn DB = new DatabaseConn(); this.amount = money; this.card_number = num; String loan_time = time; String interest_rate = rate; String[] t = new String[6]; t = schamount(card_number); // 更新数据库 double temp1 = Math.pow((1 + Double.parseDouble(interest_rate)), Double .parseDouble(loan_time)); double temp2 = Double.parseDouble(t[5].trim()) + Double.parseDouble(amount) * temp1; sql = "update loan set amount = " + temp2 + " where loan_number = " + Integer.parseInt(t[1].trim()) + " "; try { DB.OpenConn(); DB.executeUpdate(sql); } catch (Exception e) { System.out.println(e); JOptionPane.showMessageDialog(null, "贷款失败，请重新进行操作！", "警告", JOptionPane.ERROR_MESSAGE); } finally { DB.closeStmt(); DB.closeConn(); } } // 计算年利率 public Double interest_rate(String time) { String loan_time = time; double interest_rate = 0; // 计算年利率 if (Double.parseDouble(loan_time) <= 1) { interest_rate = 0.0612; } else if (Double.parseDouble(loan_time) <= 3) { interest_rate = 0.063; } else if (Double.parseDouble(loan_time) <= 5) { interest_rate = 0.0648; } else { interest_rate = 0.0684; } return interest_rate; } // 还贷 public void pay(String num) { DatabaseConn DB = new DatabaseConn(); this.card_number = num; String[] t = new String[6]; t = schamount(card_number); sql = "update loan set amount = 0 where loan_number = " + Integer.parseInt(t[1].trim()) + " "; try { DB.OpenConn(); DB.executeUpdate(sql); } catch (Exception e) { System.out.println(e); JOptionPane.showMessageDialog(null, "还贷失败，请重新进行操作！", "警告", JOptionPane.ERROR_MESSAGE); } finally { DB.closeStmt(); DB.closeConn(); } } // 验证卡号是否唯一，若不唯一，则生成新的卡号 public String CnPreclude(String testcn) { String a = testcn; DatabaseConn DB = new DatabaseConn(); String sql = "select * from login"; try { DB.OpenConn(); rs = DB.executeQuery(sql); while (rs.next()) { if ((testcn).equals(rs.getString("card_number").trim())) { String next = null; next = Integer.toString(Integer.parseInt(testcn) + 1); a = CnPreclude(next); } } } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return a; } // 验证存款账号是否唯一，若不唯一，则生成新的账号 public String depositorNum(String num) { String a = num; DatabaseConn DB = new DatabaseConn(); String sql = "select * from account"; try { DB.OpenConn(); rs = DB.executeQuery(sql); while (rs.next()) { if ((num).equals(rs.getString("account_number").trim())) { String next = null; next = Integer.toString(Integer.parseInt(num) + 1); a = depositorNum(next); } } } catch (Exception e) { } finally { DB.closeStmt(); DB.closeConn(); } return a; } // 验证贷款账号是否唯一，若不唯一，则生成新的账号 public String borrowerNum(String num) { String a = num; DatabaseConn DB = new DatabaseConn(