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Difference between revisions of "EclipseLink/Examples/MOXy/JPA"

(New page: == Overview == This example demonstrates how to derive an XML representation from a set of JPA entities using JAXB. == JPA Entities == For this example the following JPA entities will b...)
 
(Converting JPA entities to/from XML (via JAXB))
 
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== Overview ==
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== Converting JPA entities to/from XML (via JAXB) ==
 
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JPA provides an easy and powerful means to use Java objects to interact with a relational databaseThese Java objects are called entities, and have their own characteristicsSome of these characteristics (bidirectional relationships, compound keys, embedded key classes, and lazy loading) can cause challenges when mapping these objects to XML.  This example demonstrates how to easily overcome these challenges using EclipseLink MOXy (JAXB):
This example demonstrates how to derive an XML representation from a set of JPA entities using JAXB.
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* [[EclipseLink/Examples/MOXy/JPA/Relationships | Binding JPA Relationships to XML]]
 
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* [[EclipseLink/Examples/MOXy/JPA/CompoundPrimaryKeys | Binding Compound Primay Keys to XML]]
== JPA Entities ==
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* [[EclipseLink/Examples/MOXy/JPA/EmbeddedIdClass | Binding Embedded ID Classes to XML]]
 
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For this example the following JPA entities will be usedIn order to save space package names, import statements, and the get /set methods have been omitted from the following code samplesAll annotations shown below are standard JPA annotations.
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<source lang="java">
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@Entity
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public class Department {
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    @Id
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    @Column(name="D_ID")
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    private BigDecimal dId;
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    private String name;
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    @ManyToMany
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    @JoinTable(name="DEPT_EMP", joinColumns =
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        @JoinColumn(name="D_ID", referencedColumnName = "D_ID"),  
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            inverseJoinColumns = @JoinColumn(name="E_ID",
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                referencedColumnName = "E_ID"))
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    private List<Employee> member;
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}
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</source>
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<source lang="java">
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@Entity
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public class Employee {
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    @Id
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    @Column(name="E_ID")
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    private BigDecimal eId;
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    private String name;
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    @OneToOne(mappedBy="resident")
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    private Address residence;
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    @OneToMany(mappedBy="contact")
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    private List<PhoneNumber> contactNumber;
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    @ManyToMany(mappedBy="member")
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    private List<Department> team;
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}
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</source>
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<source lang="java">
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@Entity
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public class Address {
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    @Id
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    @Column(name="E_ID", insertable=false, updatable=false)
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    private BigDecimal eId;
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    private String city;
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    private String street;
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    @OneToOne
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    @JoinColumn(name="E_ID")
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    private Employee resident;
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}
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</source>
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<source lang="java">
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@Entity
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@Table(name="PHONE_NUMBER")
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public class PhoneNumber {
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    @Id
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    @Column(name="P_ID")
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    private BigDecimal pId;
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    @ManyToOne
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    @JoinColumn(name="E_ID", referencedColumnName = "E_ID")
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    private Employee contact;
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    private String num;
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}
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</source>
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Latest revision as of 12:34, 29 January 2010

Converting JPA entities to/from XML (via JAXB)

JPA provides an easy and powerful means to use Java objects to interact with a relational database. These Java objects are called entities, and have their own characteristics. Some of these characteristics (bidirectional relationships, compound keys, embedded key classes, and lazy loading) can cause challenges when mapping these objects to XML. This example demonstrates how to easily overcome these challenges using EclipseLink MOXy (JAXB):