如何更新JAXB中的特殊元素？

Question

I used Jaxb for read and write from my XML File.I want update spacial element in my XML, but I don't know how can do that in my code,any body you can till me how I can do that. That my update method

public boolean Update(Layer entity) {
  try {
  File file = new File(Test.PathXMl);
   //read from my xml
  JAXBContext jaxbContext = JAXBContext.newInstance(Project.class);
  Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
  Project project = (Project) jaxbUnmarshaller.unmarshal(file);
   // here update my XML new value but not special element
   Layer layer = new Layer();   
  layer.setLayerName(entity.getLayerName());
  layer.setOrder(entity.getOrder());
  layer.setVisible(entity.isVisible());
  project.getLayer().add(layer);
  //write in xml file 
  ObjectFactory objectFactory = new ObjectFactory();
  javax.xml.bind.Marshaller marshaller = jaxbContext.createMarshaller();
  marshaller.setProperty(marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);
  marshaller.marshal(project, new FileOutputStream(Test.PathXMl));
  } catch (FileNotFoundException e) {
    e.printStackTrace();
  } catch (JAXBException e) {
    e.printStackTrace();
  }
     return false;
 }

My XML file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Project xmlns="http://www.example.org/ProjectDataBase" name="name1">
    <Layer idLayer="2">
        <LayerName>a</LayerName>
        <Order>2</Order>
        <Visible>false</Visible>
    </Layer>
    <Layer idLayer="1">
        <LayerName>add</LayerName>
        <Order>1</Order>
        <Visible>true</Visible>
    </Layer>
</Project>

NOTE: For example I need change value in LayerName from a -->b but just in IdLayer="2" (In my code I can't select my element which I want update).Please any way for do that!!!!

Answer 1

Once you have unmarshalled the XML, you should perform the following check

// unmarshal Project
for(Layer layer : project.getLayer()) {
    if (layer.getIdLayer().equals("2")) {
        layer.setLayerName("b");
    }
}
// marshal Project back to XML