CHAPTER 6 n MAPPING WITH ANNOTATIONS 111 n (Christian web host)
CHAPTER 6 n MAPPING WITH ANNOTATIONS 111 n MAPPING WITH ANNOTATIONS 111 Listing 6-10. An Example of a Field Access Entity Mapped Across Two Tables package com.hibernatebook.annotations; import javax.persistence.*; @Entity @Table(name=”CUSTOMER”) @SecondaryTable(name=”CUSTOMER_DETAILS”) public class Customer { @Id public int id; public String name; @Column(table=”CUSTOMER_DETAILS”) public String address; } Columns in the primary or secondary tables can be marked as having unique values within their tables by adding one or more appropriate @UniqueConstraint annotations to @Table or @SecondaryTable s uniqueConstraints attribute. For example, to mark the name field in the preceding declaration as being unique, use the following: @Entity @Table( name=”CUSTOMER”, uniqueConstraints={@UniqueConstraint(columnNames=”name”)} ) @SecondaryTable(name=”CUSTOMER_DETAILS”) public class Customer { … } Persisting Basic Types with @Basic By default, properties and instance variables in your POJO are persistent Hibernate will store their values for you. The simplest mappings are therefore for the basic types. These include primitives, primitive wrappers, arrays of primitives or wrappers, enumerations, and any types that implement Serializable but are not themselves mapped entities. These are all mapped implicitly no annotation is needed. By default, such fields are mapped to a single column, and eager fetching is used to retrieve them (i.e., when the entity is retrieved from the database, all the basic fields and properties are retrieved). Also, when the field or property is not a primitive, it can be stored and retrieved as a null value. This default behavior can be overridden by applying the @Basic annotation to the appropriate class member. This annotation takes two optional attributes, and is itself entirely
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