Taming XStream part 2

Continuing on from the previous article, we will now make some adjustments to the XML and demonstrate the changes required to deserialise it into a Java obect.

<?xml version="1.0" encoding="UTF-8"?>
<xml>
    <ips state="normal">
        <ip>192.168.*.1</ip>
        <ip>127.0.0.1</ip>
        <ip>10.0.*</ip>
    </ips>
    <ips state="active">
        <ip>126.111.*</ip>
        <ip>127.0.0.1</ip>
        <ip>99.99.1.1</ip>
    </ips>
</xml>

Here we have changed the structure by saying that the ips tag is actually a list item and contains an attribute. How does our Java object change to represent this structual change?

private class XML {
    private List<IPData> ips;
    public XML(List<IPData> ips) {
        
    }
}

private class IPData {
    String state;
    List<String> list = new ArrayList<String>();
}

// The following describes this to XStream
xstream.alias("xml", XML.class);
xstream.addImplicitCollection(XML.class, "ips", IPData.class);
xstream.alias("ips", IPData.class);
xstream.aliasAttribute(IPData.class, "state", "state");
xstream.addImplicitCollection(IPData.class, "list", "ip", String.class);

In this case, we have changed the constructor definition to a list of IPData instances. This is enough to get XStream to deserialise the ips tag correctly. Also we have added the attribute definiation to convert the attribute of ips to a field of the IPData class.

The complete code listing for this is below:

package xstream;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
import java.util.ArrayList;
import java.util.List;

public class Two {
    public static void main(String[] args) {
        XStream xstream = new XStream(new DomDriver());

        xstream.alias("xml", XML.class);
        xstream.addImplicitCollection(XML.class, "ips", IPData.class);
        xstream.alias("ips", IPData.class);
        xstream.aliasAttribute(IPData.class, "state", "state");
        xstream.addImplicitCollection(IPData.class, "list", "ip", String.class);

        XML data = (XML) xstream.fromXML(
                Two.class.getResourceAsStream("ip-ranges-two.xml"));

        for (IPData d : data.ips) {
            System.out.println("State: " + d.state);
            for (String s : d.list) {
                System.out.println(s);
            }
        }
    }

    private class XML {
        private List<IPData> ips;
        public XML(List<IPData> ips) {
            
        }
    }

    private class IPData {
        String state;
        List<String> list = new ArrayList<String>();
    }
}