jpa使用uuid策略后无法手动设置id的问题

实体对象定义如下：

@Data
@Entity
@Table(name = "sys_user")
public class UserDO {

	/** 用户id */
	@Id
	@GenericGenerator(name = "uuid", strategy = "org.hibernate.id.UUIDGenerator")
	@GeneratedValue(generator = "uuid")
	@Column(length = 36, nullable = false)
	private String userId;
	....
}

调用jpa的save方法，即使手动设置了id，手动设置的这个id也会被覆盖。

要求：当用户手动设置了id，以用户设置的id为准，否则使用uuid

解决方案如下：使用自定义id生成策略，判断id非空

import cn.hutool.core.util.StrUtil;
import lombok.extern.slf4j.Slf4j;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.id.UUIDGenerator;

import javax.persistence.Id;
import java.io.Serializable;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 * 自定义uuid生成策略, 扩展 {@link org.hibernate.id.UUIDGenerator}
 * 当用户设置了id，以用户设置的id为主，为空则生成uuid
 * {@link javax.persistence.Id} 注解的字段只处理第一个
 *
 * @author qiudw
 * @date 7/7/2023
 */
@Slf4j
public class CustomerUuidGenerator extends UUIDGenerator {

	@Override
	public Serializable generate(SharedSessionContractImplementor session, Object obj) {
		Class<?> clazz = obj.getClass();
		log.debug("generate id class: {}", clazz.getName());
		Field[] fields = clazz.getDeclaredFields();
		try {
			for (Field field : fields) {
				Id idAnnotation = field.getAnnotation(Id.class);
				if (idAnnotation == null) {
					continue;
				}
				String fieldName = field.getName();
				log.debug("field name: {}", fieldName);
				String getMethodName = generateGetMethodName(fieldName);
				log.debug("get method name: {}", getMethodName);
				Method declaredMethod = clazz.getDeclaredMethod(getMethodName);
				String idValue = (String) declaredMethod.invoke(obj);
				if (StrUtil.isNotBlank(idValue)) {
					log.debug("use set value: {}", idValue);
					return idValue;
				}
			}
		} catch (NoSuchMethodException e) {
			log.error("no such method", e);
		} catch (InvocationTargetException | IllegalAccessException e) {
			log.error("invoke exception", e);
		}

		return super.generate(session, obj);
	}

	/**
	 * 生成get和set的方法名称
	 * type + 首字母大写(fieldName)
	 *
	 * @param fieldName userId
	 * @return type = set, fieldName = userId, 返回 setUserId
	 */
	private String generateGetMethodName(String fieldName) {
		return "get" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);
	}

}

实体对象使用自定的策略

@Data
@Entity
@Table(name = "sys_user")
public class UserDO {

	/** 用户id */
	@Id
	@GenericGenerator(name = "uuid", strategy = "com.user.CustomerUuidGenerator")
	@GeneratedValue(generator = "uuid")
	@Column(length = 36, nullable = false)
	private String userId;
	....
}

现在可以手动设置id了

不设置则自动生成uuid