Java 在哪里放置hibernate注释？_Java_Hibernate_Annotations

Java 在哪里放置hibernate注释？

java hibernate

Java 在哪里放置hibernate注释？,java,hibernate,annotations,Java,Hibernate,Annotations,我应该把我的hibernate注释放在哪里是我的实例变量上面的那一行吗？还是在盖特之前？还是在二传手之前？或者这真的不重要吗非常感谢这取决于你的风格。你可以把它放在场前或getter之前。在严格的JPA中，setter上的注释被忽略，但我不确定Hibernate是否遵循这一点您需要在整个实体中保持一致，或者需要在类的顶部提供一个带有默认模式的@Access注释，并在希望偏离当前类模式的每个字段/属性之前提供另一个@Access注释。您可以将它们放在字段或getter上。从《Hibernat

我应该把我的hibernate注释放在哪里

是我的实例变量上面的那一行吗？还是在盖特之前？还是在二传手之前？或者这真的不重要吗

非常感谢

这取决于你的风格。你可以把它放在场前或getter之前。在严格的JPA中，setter上的注释被忽略，但我不确定Hibernate是否遵循这一点

您需要在整个实体中保持一致，或者需要在类的顶部提供一个带有默认模式的@Access注释，并在希望偏离当前类模式的每个字段/属性之前提供另一个@Access注释。

您可以将它们放在字段或getter上。从《Hibernate注释参考指南》中：

（……）

取决于是否注释字段或方法，访问类型 Hibernate将使用字段或财产。EJB3规范要求您可以在元素上声明注释将被访问的类型，即如果使用属性，则使用getter方法访问，如果使用字段，则为字段通道在两者中混合注释应避免使用字段和方法。 Hibernate将猜测访问类型从@Id或 @嵌入ID

您可能还想了解允许强制/覆盖访问类型的

@Access

注释（在Hibernate注释3.5和JPA 2.0之前，它是Hibernate注释扩展的一部分）：

默认情况下，类的访问类型层次结构由职位定义 @Id或@EmbeddedId注释的。如果这些注释位于字段上，然后只考虑字段持久性和状态被访问通过现场。如果有注释在一个吸气剂上，然后只有吸气剂考虑持久性和状态是通过盖特/塞特。这在中国很管用推荐的做法是接近

注意

类层次结构中注释的位置必须一致（字段或属性上）将能够确定默认访问权限类型。建议您坚持使用单个注释放置战略贯穿你的整个人生应用程序

但是在某些情况下，您需要致：

强制实体层次结构的访问类型
重写类层次结构中特定实体的访问类型
重写可嵌入类型的访问类型

最好的用例是可嵌入的由多个实体使用的类可能不使用相同的访问类型。在里面在这种情况下，最好强制可嵌入类的访问类型水平

（……）

关于两种风格的利弊，我建议阅读以下问题：

@Entity: declares the class as an entity (i.e. a persistent POJO class)

@Table: is set at the class level; it allows you to define the table, catalog, and schema names for your entity mapping. If no @Table is defined the default values are used: the unqualified class name of the entity.

@Id: declares the identifier property of this entity.

@Generated Value: annotation is used to specify the primary key generation strategy to use. If the strategy is not specified by default AUTO will be used.

@Column: annotation is used to specify the details of the column to which a field or property will be mapped. If the @Column annotation is not specified by default the property name will be used as the column name.

@Inheritance – Defines the inheritance strategy to be used for an entity class hierarchy. It is specified on the entity class that is the root of the entity class hierarchy.

@DiscriminatorColumn – Is used to define the discriminator column for the SINGLE_TABLE  inheritance mapping strategies. The strategy and the discriminator column are only specified in the root of an entity class hierarchy or sub hierarchy in which a different inheritance strategy is applied

If the @DiscriminatorColumn annotation is missing, and a discriminator column is required, the name of the discriminator column defaults to "DTYPE" and the discriminator type to DiscriminatorType.STRING.

@DiscriminatorValue – Is used to specify the value of the discriminator column for entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete entity class. If the DiscriminatorValue annotation is not specified and a discriminator column is used, a provider-specific function will be used to generate a value representing the entity type. If the DiscriminatorType is STRING, the discriminator value default is the entity name.

@InheritanceType – Defines inheritance strategy options. JOINED is a strategy in which fields that are specific to a subclass are mapped to a separate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass. 

@PrimaryKeyJoinColumn – This annotation specifies a primary key column that is used as a foreign key to join to another table.

@InheritanceType – Defines inheritance strategy options. TABLE_PER_CLASS is a strategy to map table per concrete class.
@AttributeOverrides – This annotation is used to override mappings of multiple properties or fields.

@AttributeOverride – The AttributeOverride annotation is used to override the mapping of a Basic (whether explicit or default) property or field or Id property or field.

@Inheritance – Defines the inheritance strategy to be used for an entity class hierarchy. It is specified on the entity class that is the root of the entity class hierarchy.

@DiscriminatorColumn – Is used to define the discriminator column for the SINGLE_TABLE  inheritance mapping strategies. The strategy and the discriminator column are only specified in the root of an entity class hierarchy or sub hierarchy in which a different inheritance strategy is applied

If the @DiscriminatorColumn annotation is missing, and a discriminator column is required, the name of the discriminator column defaults to "DTYPE" and the discriminator type to DiscriminatorType.STRING.

@DiscriminatorValue – Is used to specify the value of the discriminator column for entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete entity class. If the DiscriminatorValue annotation is not specified and a discriminator column is used, a provider-specific function will be used to generate a value representing the entity type. If the DiscriminatorType is STRING, the discriminator value default is the entity name.

@InheritanceType – Defines inheritance strategy options. JOINED is a strategy in which fields that are specific to a subclass are mapped to a separate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass. 

@PrimaryKeyJoinColumn – This annotation specifies a primary key column that is used as a foreign key to join to another table.

@InheritanceType – Defines inheritance strategy options. TABLE_PER_CLASS is a strategy to map table per concrete class.
@AttributeOverrides – This annotation is used to override mappings of multiple properties or fields.

@AttributeOverride – The AttributeOverride annotation is used to override the mapping of a Basic (whether explicit or default) property or field or Id property or field.

@Inheritance – Defines the inheritance strategy to be used for an entity class hierarchy. It is specified on the entity class that is the root of the entity class hierarchy.

@DiscriminatorColumn – Is used to define the discriminator column for the SINGLE_TABLE  inheritance mapping strategies. The strategy and the discriminator column are only specified in the root of an entity class hierarchy or sub hierarchy in which a different inheritance strategy is applied

If the @DiscriminatorColumn annotation is missing, and a discriminator column is required, the name of the discriminator column defaults to "DTYPE" and the discriminator type to DiscriminatorType.STRING.

@DiscriminatorValue – Is used to specify the value of the discriminator column for entities of the given type. The DiscriminatorValue annotation can only be specified on a concrete entity class. If the DiscriminatorValue annotation is not specified and a discriminator column is used, a provider-specific function will be used to generate a value representing the entity type. If the DiscriminatorType is STRING, the discriminator value default is the entity name.

@InheritanceType – Defines inheritance strategy options. JOINED is a strategy in which fields that are specific to a subclass are mapped to a separate table than the fields that are common to the parent class, and a join is performed to instantiate the subclass. 

@PrimaryKeyJoinColumn – This annotation specifies a primary key column that is used as a foreign key to join to another table.

@InheritanceType – Defines inheritance strategy options. TABLE_PER_CLASS is a strategy to map table per concrete class.
@AttributeOverrides – This annotation is used to override mappings of multiple properties or fields.

@AttributeOverride – The AttributeOverride annotation is used to override the mapping of a Basic (whether explicit or default) property or field or Id property or field.

@Id@GeneratedValue

getId（）

Id