用数据库编写快递e站（本文只写了idea方面的代码）

随着快递业的不断发展，快递e站也越来越多，我们来编写一个简单的快递e站小程序，本文就介绍了如何用数据库知识编写快递e站。

##成品如下：

一、IDEA如何连接数据库

第一种方法：直接在方法体中增加连接信息

优点：如果仅使用一次数据库操作可选择
缺点：多次数据库操作每次都需要写，麻烦

public void select() { Connection conn = null; Statement stmt = null; ResultSet rs = null; try { //1.注册驱动 Class.forName("com.mysql.jdbc.Driver"); //2.定义sql String sql = "select * from kuaidi"; //3.获取conn conn = DriverManager.getConnection("jdbc:mysql:///kuaidi", "root", "123"); //4.获取执行sql对象Statement stmt = conn.createStatement(); //5.执行sql rs = stmt.executeQuery(sql); //6处理结果 while (rs.next()) { int danhao = rs.getInt(1); int qujianma = rs.getInt(2); String gongsi = rs.getString("gongsi"); String guizi = rs.getString(4); System.out.println("单号为：" + danhao + " " + "取件码为：" + qujianma + " " + "公司是：" + gongsi + " " + "柜子在第" + guizi + "个"); } } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException throwables) { throwables.printStackTrace(); } finally { if (stmt != null) { try { stmt.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } if (rs != null) { try { rs.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } } }

方法二：

建立一个JDBCHelper和一个存储数据库账号密码的Properties，来帮助快速加载驱动以及释放内存
优点：只需要写一次，用的时候调用即可
缺点：一次要写很多

释放内存的时候可能传入两个或者三个参数需要释放，所以用重载形式来解决

private static String url; private static String user; private static String password; private static String driver; /** * 文件的读取，只需要读取一次即可 */ static { //读取资源文件，并获取值 try { //1.创建properties集合类 Properties pro = new Properties(); //2.加载文件 //获取src路径下的文件的方式--->ClassLoader类加载器 ClassLoader classLoader = JDBCHelper.class.getClassLoader(); URL res = classLoader.getResource("jdbc.properties"); String path = res.getPath(); //pro.load(new FileReader("src/jdbc.properties")); pro.load(new FileReader(path)); url = pro.getProperty("url"); user = pro.getProperty("user"); password = pro.getProperty("password"); driver = pro.getProperty("driver"); Class.forName(driver); } catch (IOException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } } /** * 获取连接 * * @return连接对象 */ public static Connection getConnection() throws SQLException { return DriverManager.getConnection(url, user, password); } /** * 释放资源 * * @param stmt * @param conn */ public static void close(Statement stmt, Connection conn) { if (stmt != null) { try { stmt.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } }//释放内存 public static void close(ResultSet rs, Statement stmt, Connection conn) { if (stmt != null) { try { stmt.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } if (rs != null) { try { rs.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } if (conn != null) { try { conn.close(); } catch (SQLException throwables) { throwables.printStackTrace(); } } }

二、方法代码的实现

1.快递员增加快递

代码如下：

public class Add { Connection conn = null; Statement stmt = null; Random r= new Random(); public void addq(int danhao,String gongsi){ try { conn = JDBCHelper.getConnection(); int qujianma = r.nextInt((999999)+1); String guizi = Integer.toString(r.nextInt(100)+1); String sql = "insert into kuaidi values(" + danhao + "," + qujianma+",'"+gongsi+"','"+guizi+"')"; stmt = conn.createStatement(); int a = stmt.executeUpdate(sql); System.out.println("取件码为："+qujianma); if(a>0){ System.out.println("添加成功"); } else { System.out.println("添加失败"); } } catch (SQLException throwables) { throwables.printStackTrace(); } } }

2.快递员删除快递

代码如下：

public class Delete { Connection conn = null; Statement stmt = null; public void delete(int danhao) { try { conn = JDBCHelper.getConnection(); String sql = "delete from kuaidi where danhao = "+danhao; stmt = conn.createStatement(); int a = stmt.executeUpdate(sql); if(a>0){ System.out.println("删除成功"); } else { System.out.println("删除失败"); } } catch (SQLException throwables) { throwables.printStackTrace(); } finally { JDBCHelper.close(stmt,conn); }}

主要内容代码：

public class Imp {public static void main(String[] args) {kuaidi();}public static void kuaidi() { System.out.println("====欢迎使用新职课快递柜===="); Scanner sc = new Scanner(System.in); Random r = new Random(); while (true) { System.out.println("请输入你的身份：1-快递员，2-用户"); try { int a = sc.nextInt(); if (a < 1 || a > 2) { System.out.println("输入有误，请重新输入"); } else if (a == 1) { System.out.println("====欢迎使用新职课快递柜===="); System.out.println("请选择操作：1-存快递 2-删除快递 3-修改快递信息 4-查看所有快递"); int b = sc.nextInt(); switch (b) { case 1: { System.out.println("====欢迎使用新职课快递柜===="); System.out.println("请输入快递单号："); int danhao = sc.nextInt(); System.out.println("请输入公司名称："); String gongsi = sc.next(); Add add = new Add(); add.addq(danhao, gongsi); break; } case 2: { System.out.println("====欢迎使用新职课快递柜===="); System.out.print("请输入要删除的订单号："); int dingdan = sc.nextInt(); Delete delete = new Delete(); delete.delete(dingdan); break; } case 3: { System.out.println("====欢迎使用新职课快递柜===="); System.out.print("请输入要修改的订单号："); int danhao = sc.nextInt(); Alter al = new Alter(); boolean q = al.select(danhao); if (q = true) { System.out.println("请输入更改后的单号"); int afdanhao = sc.nextInt(); al.alter(afdanhao, danhao); } else { System.out.println("请核实订单号"); } break; } case 4: { System.out.println("====欢迎使用新职课快递柜===="); SelectAll s = new SelectAll(); s.select(); } } } else if (a == 2) { System.out.println("====欢迎使用新职课快递柜===="); System.out.println("请输入取件码"); int qujianma = sc.nextInt(); Take t = new Take(); t.take(qujianma); } } catch (InputMismatchException e) { System.out.println(); System.out.println("请输入数字序号!!!!!!!!"); System.out.println(); kuaidi(); } }}}

别的几个代码块都大同小异，只需要修改sql语句即可

如有需要全部代码，或者有疑问的同学私信我就可以了

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