如何用idea数据库编写快递e站

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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