您可以
XmlAdapter在此用例中使用：
package forum7278406;import javax.xml.bind.annotation.adapters.XmlAdapter;public class TargetAdapter extends XmlAdapter<Long, Target> { @Override public Long marshal(Target target) throws Exception { return target.getId(); } @Override public Target unmarshal(Long id) throws Exception { Target target = new Target(); target.setId(id); return target; }}该
XmlAdapter登记在
Dependency使用类
@XmlJavaTypeAdapter注释：
package forum7278406;import javax.persistence.*;import javax.xml.bind.annotation.*;import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;@Entity@XmlRootElement@XmlAccessorType(XmlAccessType.FIELD)public class Dependency { @Id @GeneratedValue private Long id; @ManyToOne(optional=false) @Column(name="target_id") @XmlJavaTypeAdapter(TargetAdapter.class) private Target target; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public Target getTarget() { return target; } public void setTarget(Target target) { this.target = target; }}走得更远
除了创建新的实例外，
Target我们还可以使用
EntityManager从数据库查询相应的实例。我们
XmlAdapter将更改为如下所示：
package forum7278406;import javax.persistence.EntityManager;import javax.xml.bind.annotation.adapters.XmlAdapter;public class TargetAdapter extends XmlAdapter<Long, Target> { EntityManager entityManager; public TargetAdapter() { } public TargetAdapter(EntityManager entityManager) { this.entityManager = entityManager; } @Override public Long marshal(Target target) throws Exception { return target.getId(); } @Override public Target unmarshal(Long id) throws Exception { Target target = null; if(null != entityManager) { target = entityManager.find(Target.class, id); } if(null == target) { target = new Target(); target.setId(id); } return target; }}现在设置的情况下
EntityManager我们的
XmlAdapter，我们可以做到以下几点：
Unmarshaller umarshaller = jaxbContext.createUnmarshaller();TargetAdapter targetAdatper = new TargetAdapter(entityManager);unmarshaller.setAdapter(targetAdapter);
