Basics of XML Parsing

[subith86]

Hi friends,

I'm new to XML-Parsing. I'd require your help to start off. My project has the following XML (not full)

<privateIdentity>
	<privateId>h9tqv1s@vodafone-3gpp.org</privateId>
	<msisdn>989845682812</msisdn>
	<preferredDomain>IMS</preferredDomain>
	<preferredAuthScheme>AKA</preferredAuthScheme>
</privateIdentity>
<ImplicitRegesteredSet>
	<IrsName>IRS__1</IrsName>
	<registrationStatus>N</registrationStatus>
</ImplicitRegesteredSet>
<publicIdentity>
	<publicId>sip:sp123@vodafone-3gpp.org</publicId>
	<IrsName>IRS__1</IrsName>
	<isDefault>true</isDefault>
</publicIdentity>

I have the following classes where each of the values have to be populated. For example, I have PrivateIdentity.java where I have the following private variables defined.

	private String privateIdentifier;
	private int msisdn;
	private String prefDomain;
	private String prefAuthScheme;

I will also have the corresponding getters and setters. As it is very obvious my job is to get the value from the XML data, for example, from the XML, I should get MSISDN as 989845682812 and put this value in the msisdn variable in PrivateIdentity.java

I am not asking for a complete code. Just the right API to use for Parsing this XML would be enough for me.

Thanks in advance.

[KevinWorkman]

Are you looking for JAXB?

[subith86]

@KevinWorkman:
I'm not sure about what JAXB is.
I had a little bit of googling after posting this and from that I think I need to make use of DOMs here. I don't know how it is but I read that it has to do something with parsing.

[subith86]

Hi,
Now I definitely require somebody's help. I wrote a code which does the parsing fine and I'm able to fetch the values of each XML tag.
The contents of parseme.txt is exactly same as the XML I have posted in the first post.

public class DocumentTest {

	public static void main(String[] args) {
		String script = "D://premdas/Desktop/file_tutorials/parseme.txt";
		DocumentBuilderFactory obj = DocumentBuilderFactory.newInstance();
		try {
			DocumentBuilder db =obj.newDocumentBuilder();
			Document doc = db.parse(new File(script));
			if (doc != null) {
				NodeList nodes = doc.getChildNodes();
				if (nodes != null) {
					iterate(nodes);
				}
			}
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		} catch (SAXException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	private static void iterate(NodeList nodeList) {
		Node nodeitem;
		for (int i=0; (nodeitem = nodeList.item(i)) != null; i++) {
			if (nodeitem.getNodeType() == Document.ELEMENT_NODE) {
				iterate(nodeitem.getChildNodes());
			} else if (nodeitem.getNodeType() == Document.TEXT_NODE){
				System.out.print(nodeitem.getParentNode().getParentNode().getNodeName()+" : ");
				System.out.println(nodeitem.getParentNode().getNodeName()+"="+nodeitem.getNodeValue());
			}
		}
	}
}

When I run the above code I get the following result.

privateIdentity : privateId=h9tqv1s@vodafone-3gpp.org
privateIdentity : msisdn=989845682812
privateIdentity : preferredDomain=IMS
privateIdentity : preferredAuthScheme=AKA
ImplicitRegesteredSet : IrsName=IRS__1
ImplicitRegesteredSet : registrationStatus=N
publicIdentity : publicId=sip:sp123@vodafone-3gpp.org
publicIdentity : IrsName=IRS__1
publicIdentity : isDefault=true

Now I'm stuck with the mapping part. How do I map XML tag "privateId" to the privateIdentifier in PrivateIdentity.java and similarly XML tag publicId to be mapped to the corresponding String variable in PublicIdentity.java and so on.
I could have written if() statements for each XML tag, but I somehow felt there will be an easier and better approach. Can someone please help.

[KevinWorkman]

Are you just asking how to assign variables to the values you're printing out here?

By the way, JAXB would do all of this for you. Just saying. :p

[subith86]

Are you just asking how to assign variables to the values you're printing out here?

Yes. Thats exactly what I want. As mentioned in the first post I have a class called PrivateIdentity.java where I have getters and setters for private members. I need to put these values that I'm printing to these variables. This is for values under privateIdentity tag. For values under ImplicitRegesteredSet tag I have another class.

I'll also give a try on JAXB. Anywhere I get blocked i'll reply to this post. Meantime if there is any good links to study JAXB that you can share, it'll be great :)

[Fubarable]

Does your XML file have an associated schema file?

Here's one decent link on jaxb: JAXB Reference Implementation — Java.net

[KevinWorkman]

Yes. Thats exactly what I want. As mentioned in the first post I have a class called PrivateIdentity.java where I have getters and setters for private members. I need to put these values that I'm printing to these variables. This is for values under privateIdentity tag. For values under ImplicitRegesteredSet tag I have another class.

I guess I'm confused. Why can't you just call the setters with the values instead of printing them out?

[subith86]

@Fubarable: Thanks for the link. I'll go through it.
In the actual testbed, there is a schema. But I'm doing this in my local machine. I don't have a schema here. I have only the XML script stored in one text file.

[subith86]

Why can't you just call the setters with the values instead of printing them out?

I could have done that but, in that case I'd require lot of "if" statements for calling the corresponding setters. In future if a new tag is introduced, i'll have to change the code also. Maybe this is how it is done, but I just wanted to know if there is any better way.

[KevinWorkman]

I could have done that but, in that case I'd require lot of "if" statements for calling the corresponding setters. In future if a new tag is introduced, i'll have to change the code also. Maybe this is how it is done, but I just wanted to know if there is any better way.

Yeah, sorry to repeat myself, but it really sounds like you're looking for JAXB.

I guess you could somehow use a Map of tag names to values, but that would probably be a hack.

[subith86]

yeah:D Even I started to realise ;)
Let me learn JAXB. Then I'll repost here.
Thanks