Why is this not possible? It seems so simple but it does not behave as expected.
Summary: Class A uses an aggregated DataA bean whereas Class B (a subclass of Class A) is using an aggregated DataB bean (whereas DataB extends DataA).
I wrote these test classes to visualize and explain my question:
Class A:
package test;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlAccessorType(XmlAccessType.NONE)
@XmlRootElement(name="root")
public class A {
private DataA source = new DataA();
@XmlElement(name="source")
public DataA getSource() {
return source;
}
public void setSource(DataA source) {
this.source = source;
}
}
and its DataA class (I used the FIELD annotation so that all fields gets marshalled):
package test;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
@XmlAccessorType(XmlAccessType.FIELD)
public class DataA {
public String string1 = "1";
public String string2 = "2";
}
And now the Class B (subclass of Class A): My goal is to reuse functionalities of A and also reuse the properties from the DataA bean by using the DataB bean:
package test;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
@XmlAccessorType(XmlAccessType.NONE)
@XmlRootElement(name="root")
public class B extends A {
private DataB source = new DataB();
public DataB getSource() {
return this.source;
}
public void setSource(DataB source) {
this.source = source;
}
}
Its corresponding DataB bean looks like this:
package test;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
@XmlAccessorType(XmlAccessType.FIELD)
public class DataB extends DataA {
public String string3 = "3";
}
Now, when I marshall an instance of class A, it gives this output:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<source>
<string1>1</string1>
<string2>2</string2>
</source>
</root>
When I marshall an instance of class B, I get the very same result:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<source>
<string1>1</string1>
<string2>2</string2>
</source>
</root>
But I expected that also string3 would get marshalled, but it is only writing the properties of bean DataA! WHY? This is not really intuitive when thinking in terms of OOP.
When I set the @XmlElement annotation also on the Class B... like this:
@XmlElement
public DataB getSource() {
return this.source;
}
... then the property gets marshalled twice because it is once annotated by the parent class as well as by the child class. This is also what I do not want:
The output now is:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<source xsi:type="dataB" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<string1>1</string1>
<string2>2</string2>
<string3>3</string3>
</source>
<source>
<string1>1</string1>
<string2>2</string2>
<string3>3</string3>
</source>
</root>
What I expected from JAXB as a result is the following XML:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
<source>
<string1>1</string1>
<string2>2</string2>
<string3>3</string3>
</source>
</root>
Any hints how to tweak JAXB to produce the expected result?? Thanks for any feedback.
@XMLElementover fields rather than public method – Machine