从数据库读取@瞬态字段

import java.io.Serializable;

public class User implements Serializable {
    private static final long serialVersionUID = 1L;

    private String username;
    private String email;
    private transient String tempToken; // 瞬态字段

    // 构造函数、getter和setter方法
    public User(String username, String email) {
        this.username = username;
        this.email = email;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getTempToken() {
        return tempToken;
    }

    public void setTempToken(String tempToken) {
        this.tempToken = tempToken;
    }
}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class UserDao {
    private Connection getConnection() throws SQLException {
        // 假设这里是获取数据库连接的代码
        return DriverManager.getConnection("jdbc:mysql://localhost:3306/mydb", "user", "password");
    }

    public User getUserByUsername(String username) {
        String sql = "SELECT username, email FROM users WHERE username = ?";
        try (Connection conn = getConnection();
             PreparedStatement ps = conn.prepareStatement(sql)) {
            ps.setString(1, username);
            ResultSet rs = ps.executeQuery();
            if (rs.next()) {
                User user = new User(rs.getString("username"), rs.getString("email"));
                // 手动设置瞬态字段的值
                user.setTempToken(generateTempToken());
                return user;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

    private String generateTempToken() {
        // 生成临时令牌的逻辑
        return "tempToken-" + System.currentTimeMillis();
    }
}