Java期末测试

//1.定义一个图形接口，一个有抽象方法求周长
interface Shape{
  double girth(int length);
}
//2.子类圆形实现接口
class Circle implements Shape{
  int r;
  //创建有参构造方法
  public Circle(int r) {
    super();
    //将r赋值给成员变量r,this.r调用成员变量
    this.r = r;
  }
  //重写girth()方法，求出周长
  @Override
  public double girth(int length) {
    // TODO Auto-generated method stub
    return 2*3.14*length;
  }
}
//3.测试类
public class ShapeTest {
  public static void main(String[] args) {
    //将长度2添加到Circle对象中
    Circle c = new Circle(2);
    //通过Circle对象调用girth()方法
    System.out.println(c.girth(c.r));
  }
}

public class RandomTest {
  public static void main(String[] args) {
    //1.创建数组
    int[] arr = new int[30];
    //2.创建随机数对象
    Random random = new Random();
    //3.for循环，将随机数存到数组
    for(int i = 0;i<arr.length;i++) {
      arr[i] = random.nextInt(61)+500;
    }
    //4.for-each全部输出,升序
    Arrays.sort(arr);
    for (int a : arr) {
      System.out.print("\t"+a);
    }
  }
}

public class ObjectTest {
  public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException {
    //创建有参对象
    Stu s1 = new Stu("11","aa");
    Stu s2 = new Stu("22","bb");
    Stu s3 = new Stu("11","cc");
    //创建集合，将对象添加进去
    HashSet hs = new HashSet();
    hs.add(s1);
    hs.add(s2);
    hs.add(s3);
    ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("D:\\a.txt"));
    //迭代器遍历
    Iterator iterator = hs.iterator();
    while(iterator.hasNext()) {
      Stu stu = (Stu)iterator.next();
      oos.writeObject(stu);
    }
    //关闭流
    oos.close();
    //对象输入流
    ObjectInputStream ois = new ObjectInputStream(new FileInputStream("D:\\a.txt"));
    //读数据
    Stu stu1 = (Stu)ois.readObject();
    Stu stu2 = (Stu)ois.readObject();
    //显示在控制台
    System.out.println(stu1);
    System.out.println(stu2);
    //关闭流
    ois.close();
  }
}
class Stu implements Serializable{
  String id,name;
  public Stu() {
    super();
    // TODO Auto-generated constructor stub
  }
  public Stu(String id, String name) {
    super();
    this.id = id;
    this.name = name;
  }
  @Override
  public String toString() {
    return "id=" + id + ", name=" + name ;
  }
  @Override
  public int hashCode() {
    // TODO Auto-generated method stub
    return this.id.hashCode();
  }
  @Override
  public boolean equals(Object obj) {
    Stu s = (Stu)obj;
    return this.id.equals(s.id);
  }
}

public class JframeLogin {
  public static void main(String[] args) {
    //创建窗口
    JFrame frame = new JFrame("窗口");
    //设置窗口
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setBounds(500,200,300,200);
    //创建面板
    JPanel panel = new JPanel();
    //创建组件
    Label label1 = new Label("账号：");
    JTextField textField1 = new JTextField(10);
    Label label2 = new Label("密码：");
    JPasswordField textField2 = new JPasswordField(10);
    JButton button = new JButton("登录");
    //将组件添加到面板上
    panel.add(label1);
    panel.add(textField1);
    panel.add(label2);
    panel.add(textField2);
    panel.add(button);
    //将面板添加到窗口上
    frame.add(panel);
    //可见窗口
    frame.setVisible(true);
    //事件处理
    button.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        //获取用户名输入框
        String username = textField1.getText();
        //获取密码框
        String pwd = new String(textField2.getPassword());
        //判断用户名和密码
        if(username.equals("123") && pwd.equals("123")) {
          //弹窗
          JOptionPane.showMessageDialog(frame, "登录成功");
        }else {
          JOptionPane.showMessageDialog(frame, "登录失败");
        }
      }
    });
  }
}

public class SelectTest {
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    JFrame jf = new JFrame("查询");
    jf.setBounds(500, 200, 400 ,300);
    jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    //窗体上放中间容器
    JPanel jp = new JPanel();
    //面板上摆放组件
    JLabel jl = new JLabel("请输入账号");
    JTextField field = new JTextField(15);
    JButton btn = new JButton("查找");
    //将组件添加到面板上
    jp.add(jl);
    jp.add(field);
    jp.add(btn);
    //将面板添加到窗体上
    jf.add(jp);
    jf.setVisible(true);
    //事件处理
    btn.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        Connection con = null;
        Statement sta = null;
        ResultSet rs = null;
        String url = "jdbc:mysql://localhost:3306/teacherinfo?serverTimezone=UTC&useSSL=false";
        String user = "root";
        String password = "123456";
        try {
          Class.forName("com.mysql.cj.jdbc.Driver");
          con = DriverManager.getConnection(url, user, password);
          sta = con.createStatement();
          rs = sta.executeQuery("select * from info");
          boolean flag = false;
          while(rs.next()) {
            int id = rs.getInt(1);
            String idTxt = field.getText();
            if (idTxt.equals(String.valueOf(id))) {
              flag = true;
              break;
            }
          }
          if (flag==true) {
            JOptionPane.showMessageDialog(jf, "查找到了");
          }else {
            JOptionPane.showMessageDialog(jf, "没有找到");
          }
        } catch (ClassNotFoundException e1) {
          // TODO Auto-generated catch block
          e1.printStackTrace();
        } catch (SQLException e1) {
          // TODO Auto-generated catch block
          e1.printStackTrace();
        }finally {
          if (rs!=null) {
            try {
              rs.close();
            } catch (SQLException e1) {
              // TODO Auto-generated catch block
              e1.printStackTrace();
            }
          }
          if (sta!=null) {
            try {
              sta.close();
            } catch (SQLException e1) {
              // TODO Auto-generated catch block
              e1.printStackTrace();
            }
          }
          if(con!=null) {
            try {
              con.close();
            } catch (SQLException e1) {
              // TODO Auto-generated catch block
              e1.printStackTrace();
            }
          }
        }
      }
    });
  }
}