java - Hibernate 5 字节码增强关联管理仅朝一个方向工作

Question

我有 2 个 JPA 实体，如下所示:

@MappedSuperclass
public class AbstractEntity {

    private static final String INCREMENT_STRATEGY = "increment";

    private static final String INCREMENT_ID_GENERATOR_NAME = "INCREMENT_ID_GENERATOR";
    
    @Id
    @GenericGenerator(name = INCREMENT_ID_GENERATOR_NAME, strategy = INCREMENT_STRATEGY)
    @GeneratedValue(generator = INCREMENT_ID_GENERATOR_NAME)
    private Long id;

    public AbstractEntity() {
        super();
    }
    
    public Long getId() {
        return id;
    }
}

@Entity
public class Department extends AbstractEntity{
    
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "department")
    private List<Employee> employees = new ArrayList<Employee>();

    public void setEmployees(List<Employee> employees) {
        this.employees = employees;
    }
    
    public List<Employee> getEmployees() {
        return employees;
    }

}

@Entity
public class Employee extends AbstractEntity {

    @ManyToOne(optional = true, cascade= CascadeType.ALL)
    @JoinColumn(name = "DEPARTMENT_ID")
    private Department department;

    public void setDepartment(Department department) {
        this.department = department;
    }

    public Department getDepartment() {
        return department;
    }

}

所有类均使用 hibernate 增强 maven 插件进行字节码增强:

<build>
    <plugins>
        <plugin>
            <groupId>org.hibernate.orm.tooling</groupId>
            <artifactId>hibernate-enhance-maven-plugin</artifactId>
            <version>5.2.2.Final</version>
            <dependencies>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-entitymanager</artifactId>
                    <version>5.2.2.Final</version>
                </dependency>
            </dependencies>
            <configuration>
                <enableDirtyTracking>true</enableDirtyTracking>
                <enableLazyInitialization>true</enableLazyInitialization>
                <enableAssociationManagement>true</enableAssociationManagement>
            </configuration>
        </plugin>
    </plugins>
</build>

我运行了两个测试来验证增强类是否正常工作:

@Test
public void test1() {
    Department department = new Department();
    Employee employee = new Employee();
    department.getEmployees().add(employee);
    assertThat(employee.getDepartment(), is(not(nullValue())));
}

@Test
public void test2() {
    Department department = new Department();
    Employee employee = new Employee();
    employee.setDepartment(department);
    assertThat(department.getEmployees().size(), is(1));
    assertThat(department.getEmployees().get(0), is(employee));
}

只有第二个测试成功通过，因此当通过父级集合操作关联时，子级的父级字段不会更新，而在 Hibernate ORM 5.2.3.Final User Guide 中据说

Bytecode-enhanced bi-directional association management makes that first example work by managing the "other side" of a bi-directional association whenever one side is manipulated.

引用“第一个示例”的位置

Example 204. Incorrect normal Java usage

为什么在我的 test1 案例中关联管理不起作用？我做错了什么？

Answer 1

在单元测试中，类可能没有得到增强，特别是当您通过 IDE 运行它们时。

确保增强类包含在您在进行测试的项目中导入的不同模块中。

或者您可以运行增强过程，验证类是否已增强，然后才运行单元测试。

总而言之，我猜您可能正在运行实体类的未增强版本。

无论如何，我认为这个功能并不是真的有必要。 Syncing both ends of the associations is the way to go ，并且只需要您提供addChild和removeChild方法。