Unmarshalling complex XML into java using Spring batch

Question

I use Spring batch in order to parse XML documents and act upon the data contained in the those XML documents.

I have documents such as the one below:

<rootDoc>
  <group id="13001L000001" box="13000B000001" operator="jsmith">
    <mail numMail="3A06049714560"/>
    <mail numMail="3A06049714561"/>
    <mail numMail="3A06049714562"/>
    <mail numMail="3A06049714565"/>
  </group>
  <group id="13001L000002" box="13000B000001" operator="jsmith">
    <mail numMail="3A06049714570"/>
    <mail numMail="3A06049714571"/>
    <mail numMail="3A06049714572"/>
    <mail numMail="3A06049714575"/>
  </group>
</rootDoc>

Ideally, for each document I want to be able to obtain a collection of groups and for each group a collection of mails

I am not sure how to use XStream for that purpose... Is it possible to achieve what I want to do with XStream or do I need JaxB?

Answer 1

XStream would be the 'easiest' imho - essentially allowing you to quickly construct a set of POJO's that would map the document and then use XStream configurations to parse the document into them. for instance for the rootDoc;

import java.io.Serializable;
import java.util.List;

public class Root implements Serializable {

private List<Group> groups;

//setters and getters...

}

for the Group

import java.io.Serializable;
import java.util.List;

public class Group implements Serializable {

private String id;

private String box;

private String operator;

private List<Mail> mailItems;

//setters and getters...

}

and for the Mail Item

import java.io.Serializable;

public class Mail implements Serializable {

private String numMail;

//setters and getters...

}

to setup XStream for this object the following configuration could be used

    XStream xstream = new XStream(new StaxDriver());
    xstream.alias("mail", Mail.class);
    xstream.useAttributeFor(Mail.class,"numMail");
    xstream.alias("group", Group.class);
    xstream.useAttributeFor(Group.class, "box");
    xstream.useAttributeFor(Group.class, "id");
    xstream.useAttributeFor(Group.class, "operator");
    xstream.addImplicitCollection(Group.class, "mailItems");
    xstream.alias("rootDoc", Root.class);
    xstream.addImplicitCollection(Root.class, "groups");

and to use it to read the document

Root result = (Root) xstream.fromXML(...source);

now you can use the Root POJO as you would any parent object and retrieve the corresponding Groups and Mail Items.