Lombok @Builder和JPA默认构造函数

Question

我正在将Lombok项目与Spring Data JPA一起使用。有什么方法可以将Lombok @Builder与JPA默认构造函数连接？

码：

@Entity 
@Builder
class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
}

据我所知，JPA需要默认的构造函数，该构造函数被@Builder注解覆盖。有什么解决方法吗？

这段代码给我错误： org.hibernate.InstantiationException: No default constructor for entity: : app.domain.model.Person

Answer 1

更新

根据反馈和John的回答，我已更新了不再使用@Tolerateor的答案@Data，而是通过@Getter和创建访问器和变量，通过@Setter创建默认构造函数via@NoArgsConstructor，最后我们创建了构建器通过via所需的所有args构造函数@AllArgsConstructor。

因为您想使用构建器模式，所以我想您想限制构造函数和mutators方法的可见性。为此，我们package private通过和注释上的属性以及注释上的access属性将可见性设置为。@NoArgsConstructor``@AllArgsConstructor``value``@Setter

重要

记住要正确重写toString，equals和hashCode。有关详细信息，请参见Vlad Mihalcea的以下帖子：

• 最佳的实现方式，将哈希码和字符串与jpa并休眠
• 如何使用jpa实体标识符实现等于和哈希码
• 休眠事实等于哈希码

    package com.stackoverflow.SO34299054;

    import static org.junit.Assert.*;

    import java.util.Random;

    import javax.persistence.Entity;
    import javax.persistence.GeneratedValue;
    import javax.persistence.GenerationType;
    import javax.persistence.Id;

    import org.junit.Test;

    import lombok.AccessLevel;
    import lombok.AllArgsConstructor;
    import lombok.Builder;
    import lombok.Getter;
    import lombok.NoArgsConstructor;
    import lombok.Setter;

    @SuppressWarnings("javadoc")
    public class Answer {

        @Entity
        @Builder(toBuilder = true)
        @AllArgsConstructor(access = AccessLevel.PACKAGE)
        @NoArgsConstructor(access = AccessLevel.PACKAGE)
        @Setter(value = AccessLevel.PACKAGE)
        @Getter
        public static class Person {

            @Id
            @GeneratedValue(strategy = GenerationType.AUTO)
            private Long id;

            /*
             * IMPORTANT:
             * Set toString, equals, and hashCode as described in these
             * documents:
             * - https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/
             * - https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
             * - https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/
             */
        }

        /**
         * Test person builder.
         */
        @Test
        public void testPersonBuilder() {

            final Long expectedId = new Random().nextLong();
            final Person fromBuilder = Person.builder()
                .id(expectedId)
                .build();
            assertEquals(expectedId, fromBuilder.getId());

        }

        /**
         * Test person constructor.
         */
        @Test
        public void testPersonConstructor() {

            final Long expectedId = new Random().nextLong();
            final Person fromNoArgConstructor = new Person();
            fromNoArgConstructor.setId(expectedId);
            assertEquals(expectedId, fromNoArgConstructor.getId());
        }
    }

旧版本使用@Tolerate和@Data：

使用@Toleratework允许添加noarg构造函数。

因为您想使用构建器模式，所以我想您想控制setter方法的可见性。

该@Data注解使得生成的制定者public，应用@Setter(value =AccessLevel.PROTECTED)的领域，因此他们protected。

记住要正确重写toString，equals和hashCode。有关详细信息，请参见Vlad Mihalcea的以下帖子：

• 最佳的实现方式，将哈希码和字符串与jpa并休眠
• 如何使用jpa实体标识符实现等于和哈希码
• 休眠事实等于哈希码

    package lombok.javac.handlers.stackoverflow;

    import static org.junit.Assert.*;

    import java.util.Random;

    import javax.persistence.GenerationType;
    import javax.persistence.GeneratedValue;
    import javax.persistence.Id;

    import lombok.AccessLevel;
    import lombok.Builder;
    import lombok.Data;
    import lombok.Setter;
    import lombok.experimental.Tolerate;

    import org.junit.Test;

    public class So34241718 {

        @Builder
        @Data
        public static class Person {

            @Id
            @GeneratedValue(strategy = GenerationType.AUTO)
            @Setter(value = AccessLevel.PROTECTED)
            Long id;

            @Tolerate
            Person() {}

           /* IMPORTANT:
              Override toString, equals, and hashCode as described in these 
              documents:
              - https://vladmihalcea.com/the-best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate/
              - https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
              - https://vladmihalcea.com/hibernate-facts-equals-and-hashcode/
              */
        }

        @Test
        public void testPersonBuilder() {

            Long expectedId = new Random().nextLong();
            final Person fromBuilder = Person.builder()
                .id(expectedId)
                .build();
            assertEquals(expectedId, fromBuilder.getId());

        }

        @Test
        public void testPersonConstructor() {

            Long expectedId = new Random().nextLong();
            final Person fromNoArgConstructor = new Person();
            fromNoArgConstructor .setId(expectedId);
            assertEquals(expectedId, fromNoArgConstructor.getId());
        }
    }