marshall attributes inside XML elements with JAXB - spring

Question

I work with Spring JPA and have the following entity:
#Entity
#Table(name = Constants.ENTITY_TABLE_PREFIX + "ENTRY")
#XmlAccessorType(XmlAccessType.NONE)
#XmlRootElement(name = "monObj_info")
public class EntryXML implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.IDENTITY)
#XmlAttribute
private long id;
#Column(name = "ip_address", nullable = true)
#XmlElement
private String ip_address;
#Column(name = "network_element_name", nullable = false)
#XmlElement
private String network_element_name;
public EntryXML() {}
public EntryXML(long id, String ip_address, String network_element_name) {
super();
this.id = id;
this.ip_address = ip_address;
this.network_element_name = network_element_name;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getIp_address() {
return ip_address;
}
public void setIp_address(String ip_address) {
this.ip_address = ip_address;
}
public String getNetwork_element_name() {
return network_element_name;
}
public void setNetwork_element_name(String network_element_name) {
this.network_element_name = network_element_name;
}
}
and the endpoint:
#RestController
public class EntryXMLEndpoint {
#Autowired
private IEntryXMLService service;
#RequestMapping(value = "/restxml", produces = { "application/xml" })
public EntryXML findEntries() {
EntryXML record = service.findById(1);
return record;
}
}
Now the requested response is:
<monObj_info id="1">
<atribute name="ip_address" value="xx.xxx.xxx.x"/>
<atribute name="network_element_name" value="xxxxxx"/>
</monObj_info>
Of course what I get is :
<monObj_info id="1">
<ip_address>xx.xxx.xxx.x</ip_address>
<network_element_name>xxxxxx</network_element_name>
</monObj_info>
I read similar posts , but the problem is I cannot create a List with the required elements inside my Entity Class, since it will not map with any column in the respective table, any suggestions?

Answer 1

You can achieve your goal in a straight-forward but somewhat hackish way.
Since you don't want the ip_address and network_element_name properties
to be marshalled and unmarshalled directly, you need to remove their #XmlElement annotation
and add #XmlTransient.
Instead, you want some <atribute name="..." value="..." /> elements marshalled and unmarshalled.
Therefore you need to add the following things to your EntryXML class:
an attributes property holding a list of attributes.
It is annotated with #XmlElement so that it will be part of XML marshalling and unmarshalling.
It is annotated with #Transient so that it will not be part of database persistence.
a simple helper class Attribute for holding name and value.
name and value are annotated with #XmlAttribute so that they will be part of XML marshalling and unmarshalling.
a Marshal Event Callback (beforeMarshal)
for doing the conversion from ip_address and network_element_name
to the attributes list.
an Unmarshal Event Callback (afterUnmarshal)
for doing the opposite conversion.
#XmlElement(name = "atribute")
#Transient // from package javax.persistence
private List<Attribute> attributes;
// there is no need for getAttributes and setAttributes methods
private static class Attribute {
#SuppressWarnings("unused") // called by the unmarshaller
Attribute() {
}
Attribute(String name, String value) {
this.name = name;
this.value = value;
}
#XmlAttribute
private String name;
#XmlAttribute
private String value;
}
#SuppressWarnings("unused") // this method is called only by the marshaller
private boolean beforeMarshal(Marshaller marshaller) {
attributes = new ArrayList<>();
attributes.add(new Attribute("ip_address", ip_address));
attributes.add(new Attribute("network_element_name", network_element_name));
return true;
}
#SuppressWarnings("unused") // this method is called only by the unmarshaller
private void afterUnmarshal(Unmarshaller unmarshaller, Object parent) {
if (attributes != null) {
for (Attribute attribute : attributes) {
switch (attribute.name) {
case "ip_address":
ip_address = attribute.value;
break;
case "network_element_name":
network_element_name = attribute.value;
break;
}
}
}
}
Then the XML output will look like this:
<monObj_info id="1">
<atribute name="ip_address" value="xx.xxx.xxx.x"/>
<atribute name="network_element_name" value="xxxxxx"/>
</monObj_info>