Lombok @Builder 和 JPA 默认构造函数 [英] Lombok @Builder and JPA Default constructor
问题描述
我将 Lombok 项目与 Spring Data JPA 一起使用.有没有办法将 Lombok @Builder 与 JPA 默认构造函数连接起来?
I'm using project Lombok together with Spring Data JPA.
Is there any way to connect Lombok @Builder with JPA default constructor?
代码:
@Entity
@Builder
class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
}
据我所知，JPA 需要由 @Builder 注释覆盖的默认构造函数.有什么解决方法吗?
As far as I know JPA needs default constructor which is overriden by @Builder annotation. Is there any workaround for that?
这段代码给了我错误:org.hibernate.InstantiationException:实体没有默认构造函数::app.domain.model.Person
推荐答案
更新
根据反馈和约翰的答案，我更新了答案，不再使用 @Tolerate 或 @Data，而是通过 @Getter 和 @Setter 创建访问器和修改器，通过 创建默认构造函数>@NoArgsConstructor，最后我们通过@AllArgsConstructor创建构建器需要的所有参数构造函数.
Based on the feedback and John's answer I have updated the answer to no longer use @Tolerate or @Data and instead we create accessors and mutators via @Getter and @Setter, create the default constructor via @NoArgsConstructor, and finally we create the all args constructor that the builder requires via @AllArgsConstructor.
由于您想使用构建器模式，我想您想限制构造函数和修改器方法的可见性.为了实现这一点，我们通过 @NoArgsConstructor 和 @AllArgsConstructor 注释上的 access 属性将可见性设置为 package private以及 @Setter 注释上的 value 属性.
Since you want to use the builder pattern I imagine you want to restrict visibility of the constructor and mutators methods.
To achieve this we set the visibility to package private via the access attribute on the @NoArgsConstructor and @AllArgsConstructor annotations and the value attribute on the @Setterannotation.
重要
记得正确覆盖toString、equals 和hashCode.有关详细信息，请参阅 Vlad Mihalcea 的以下帖子:
Remember to properly override toString, equals, and hashCode.
See the following posts by Vlad Mihalcea for details:
- -best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
- 如何实施-equals-and-hashcode-using-the-jpa-entity-identifier
- hibernate-facts-equals-and-hashcode
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());
}
}
使用@Tolerate 和@Data 的旧版本:
Old Version using @Tolerate and @Data:
使用 @Tolerate 可以允许添加 noarg 构造函数.
Using @Tolerate worked to allow adding a noarg constructor.
既然你想使用构建器模式，我想你想控制 setter 方法的可见性.
Since you want to use the builder pattern I imagine you want to control visibility of the setter methods.
@Data 注释使生成的 setter public，将 @Setter(value = AccessLevel.PROTECTED) 应用于字段使它们 <代码>受保护.
The @Data annotation makes the generated setters public, applying @Setter(value = AccessLevel.PROTECTED) to the fields makes them protected.
记得正确覆盖toString、equals 和hashCode.有关详细信息，请参阅 Vlad Mihalcea 的以下帖子:
Remember to properly override toString, equals, and hashCode.
See the following posts by Vlad Mihalcea for details:
- -best-way-to-implement-equals-hashcode-and-tostring-with-jpa-and-hibernate
- 如何实施-equals-and-hashcode-using-the-jpa-entity-identifier
- hibernate-facts-equals-and-hashcode
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());
}
}
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