用java写一个学生管理系统，需要通过javaswing录入和更新学生信息到mysql里，并可以提示重复学号录入

好的，我可以为您提供一些思路和代码示例。首先，您需要安装MySQL数据库，并创建一个名为“studentdb”的数据库。然后，您可以创建一个名为“student”的表，其中包含学生ID、姓名、年龄和性别等信息。以下是一个示例表：

CREATE TABLE student (
  id INT NOT NULL AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  age INT NOT NULL,
  gender VARCHAR(10) NOT NULL,
  PRIMARY KEY (id)
);

接下来，您可以使用Java Swing创建一个图形用户界面（GUI），用于录入和更新学生信息。以下是一个示例GUI：

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.sql.*;

public class StudentManagementSystem extends JFrame implements ActionListener {
    private JLabel idLabel, nameLabel, ageLabel, genderLabel;
    private JTextField idField, nameField, ageField, genderField;
    private JButton addButton, updateButton;
    
    public StudentManagementSystem() {
        super("学生管理系统");
        
        idLabel = new JLabel("学号：");
        nameLabel = new JLabel("姓名：");
        ageLabel = new JLabel("年龄：");
        genderLabel = new JLabel("性别：");
        
        idField = new JTextField(10);
        nameField = new JTextField(10);
        ageField = new JTextField(10);
        genderField = new JTextField(10);
        
        addButton = new JButton("添加");
        updateButton = new JButton("更新");
        
        addButton.addActionListener(this);
        updateButton.addActionListener(this);
        
        JPanel panel = new JPanel(new GridLayout(5, 2));
        panel.add(idLabel);
        panel.add(idField);
        panel.add(nameLabel);
        panel.add(nameField);
        panel.add(ageLabel);
        panel.add(ageField);
        panel.add(genderLabel);
        panel.add(genderField);
        panel.add(addButton);
        panel.add(updateButton);
        
        setContentPane(panel);
        pack();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }
    
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == addButton) {
            addStudent();
        } else if (e.getSource() == updateButton) {
            updateStudent();
        }
    }
    
    private void addStudent() {
        String id = idField.getText();
        String name = nameField.getText();
        String age = ageField.getText();
        String gender = genderField.getText();
        
        if (id.equals("") || name.equals("") || age.equals("") || gender.equals("")) {
            JOptionPane.showMessageDialog(this, "请输入完整的学生信息！", "提示", JOptionPane.WARNING_MESSAGE);
            return;
        }
        
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/studentdb";
            String username = "root";
            String password = "123456";
            Connection conn = DriverManager.getConnection(url, username, password);
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM student WHERE id='" + id + "'");
            if (rs.next()) {
                JOptionPane.showMessageDialog(this, "学号已存在，请重新输入！", "提示", JOptionPane.WARNING_MESSAGE);
                return;
            }
            stmt.executeUpdate("INSERT INTO student (id, name, age, gender) VALUES ('" + id + "', '" + name + "', '" + age + "', '" + gender + "')");
            JOptionPane.showMessageDialog(this, "添加成功！", "提示", JOptionPane.INFORMATION_MESSAGE);
            idField.setText("");
            nameField.setText("");
            ageField.setText("");
            genderField.setText("");
            conn.close();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
    }
    
    private void updateStudent() {
        String id = idField.getText();
        String name = nameField.getText();
        String age = ageField.getText();
        String gender = genderField.getText();
        
        if (id.equals("") || name.equals("") || age.equals("") || gender.equals("")) {
            JOptionPane.showMessageDialog(this, "请输入完整的学生信息！", "提示", JOptionPane.WARNING_MESSAGE);
            return;
        }
        
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/studentdb";
            String username = "root";
            String password = "123456";
            Connection conn = DriverManager.getConnection(url, username, password);
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT * FROM student WHERE id='" + id + "'");
            if (!rs.next()) {
                JOptionPane.showMessageDialog(this, "学号不存在，请重新输入！", "提示", JOptionPane.WARNING_MESSAGE);
                return;
            }
            stmt.executeUpdate("UPDATE student SET name='" + name + "', age='" + age + "', gender='" + gender + "' WHERE id='" + id + "'");
            JOptionPane.showMessageDialog(this, "更新成功！", "提示", JOptionPane.INFORMATION_MESSAGE);
            idField.setText("");
            nameField.setText("");
            ageField.setText("");
            genderField.setText("");
            conn.close();
        } catch (ClassNotFoundException ex) {
            ex.printStackTrace();
        } catch (SQLException ex) {
            ex.printStackTrace();
        }
    }
    
    public static void main(String[] args) {
        new StudentManagementSystem();
    }
}

在上面的GUI中，我们使用了一个JPanel来包含所有的组件，然后将其作为内容面板设置到JFrame中。在添加和更新学生信息时，我们使用了JOptionPane来显示提示框。在数据库操作中，我们使用了JDBC API来连接和操作MySQL数据库。

希望这个示例可以帮助您完成学生管理系统的开发。如果您有任何问题，请随时向我提问！