深入理解Spring Data JPA查询方法中的Is关键字：功能与实践

import jakarta.persistence.Entity;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import java.util.Date;

@Entity
public class Reservation {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private Date reservationDate; // 使用reservationDate以避免与Date类型冲突

    // 构造函数
    public Reservation() {}

    public Reservation(String username, Date reservationDate) {
        this.username = username;
        this.reservationDate = reservationDate;
    }

    // Getters and Setters
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getUsername() { return username; }
    public void setUsername(String username) { this.username = username; }
    public Date getReservationDate() { return reservationDate; }
    public void setReservationDate(Date reservationDate) { this.reservationDate = reservationDate; }

    @Override
    public String toString() {
        return "Reservation{" +
               "id=" + id +
               ", username='" + username + '\'' +
               ", reservationDate=" + reservationDate +
               '}';
    }
}

import org.springframework.data.jpa.repository.JpaRepository;
import java.util.Date;
import java.util.List;

public interface ReservationRepository extends JpaRepository<Reservation, Long> {

    /**
     * 查询指定用户在指定日期之后或当天预订的所有记录（不使用Is关键字）
     * @param username 用户名
     * @param date 日期
     * @return 预订列表
     */
    List<Reservation> findByUsernameAndReservationDateGreaterThanEqual(String username, Date date);

    /**
     * 查询指定用户在指定日期之后或当天预订的所有记录（使用Is关键字）
     * 功能上与上一个方法完全相同
     * @param username 用户名
     * @param date 日期
     * @return 预订列表
     */
    List<Reservation> findByUsernameAndReservationDateIsGreaterThanEqual(String username, Date date);

    // 另一个常见例子：布尔类型字段
    // 假设User实体有一个boolean active字段
    // List<User> findByActiveTrue();    // 查询active为真的用户
    // List<User> findByIsActiveTrue();  // 功能相同，可能更具可读性
}

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.Date;
import java.util.List;

@Service
public class ReservationService {

    @Autowired
    private ReservationRepository reservationRepository;

    public List<Reservation> getUpcomingReservationsForUser(String username, Date currentDate) {
        // 两种调用方式均可，效果一致
        System.out.println("使用 findByUsernameAndReservationDateGreaterThanEqual:");
        List<Reservation> reservations1 = reservationRepository.findByUsernameAndReservationDateGreaterThanEqual(username, currentDate);
        reservations1.forEach(System.out::println);

        System.out.println("\n使用 findByUsernameAndReservationDateIsGreaterThanEqual:");
        List<Reservation> reservations2 = reservationRepository.findByUsernameAndReservationDateIsGreaterThanEqual(username, currentDate);
        reservations2.forEach(System.out::println);

        // 返回其中一个即可，因为它们结果相同
        return reservations1;
    }
}