where to start with parsing XML

[J. Kevin Robbins]

I'm finally able to consume web services through our proxy server and now I have a XML file. Where do I start with parsing? I'm confused by the plethora of parsers; SAX, DOM, XSLT, Xerces, etc., and don't know where to start.

If it makes a difference, I'm getting the XML from the National Weather Service to build a web page with the weather forecast. I don't want all our users constantly hitting the NWS website so I need to store this information. I'm thinking I need to populate a bean and store it in the context.

Any tips on how to get started? Am I on the right track?

[J. Kevin Robbins]

So I stumbled onto this site. It seems like a decent approach, but I'm confused by this code:

Finally, to create your objects you can use the JAXB unmarshaller.

JAXBContext jc = JAXBContext.newInstance("my.package.name");
Unmarshaller unmarshaller = jc.createUnmarshaller();
MyFile myFile = (MyFile) unmarshaller.unmarshal(new File( "myFile.xml"));

What is that MyFile object in the last line? The page doesn't explain where this came from.

[John Jai]

Jk Robbins wrote:I'm finally able to consume web services through our proxy server and now I have a XML file.

What is the XML file you are getting from the web services. Are you mentioning about the SOAP wsdl file?

SAX and DOM are popular XML programming interfaces. If it's like you need to parse an XML file and store it in a cache, you can use either of them and extract data from the desired nodes.

SAX and DOM examples will be plenty on the internet or if you search this forum.

[Paul Clapham]

But that site is just a quick overview of what you would do if you knew how to use JAXB. A proper treatment of JAXB would require... well, however many pages the JAXB tutorial requires. It's a lot. I thought I had a copy on my machine but I don't, but anyway I recommend having a look at it. Your google keywords are jaxb tutorial (of course).

[J. Kevin Robbins]

I should have been clearer. I'm using a REST call; no WSDL involved. This is what I have so far:

public class ApacheHttpRestClient1 {

    public static void main(String[] args) {
        DefaultHttpClient httpclient = new DefaultHttpClient();
        NTCredentials creds = new NTCredentials("userid", "pwd", "server", "domain");
        httpclient.getCredentialsProvider().setCredentials(AuthScope.ANY, creds);
        String getParams = "/xml/sample_products/browser_interface/ndfdXMLclient.php?zipCodeList=24540";
        getParams += "&product=time-series&begin=2012-07-10T00:00:00&end=2012-07-11T00:00:00";
        getParams += "&maxt=maxt&mint=mint&appt=appt&pop12=pop12&rh=rh&wx=wx&icons=icons&wwa=wwa";
        try {
            // specify the host, protocol, and port
            HttpHost target = new HttpHost("graphical.weather.gov", 80, "http");
            HttpContext localContext = new BasicHttpContext();

            // specify the get request
            HttpGet getRequest = new HttpGet(getParams);

            System.out.println("executing request to " + target);

            HttpResponse httpResponse = httpclient.execute(target, getRequest);
            HttpEntity entity = httpResponse.getEntity();

            System.out.println("----------------------------------------");
            System.out.println(httpResponse.getStatusLine());
            Header[] headers = httpResponse.getAllHeaders();
            for (int i = 0; i < headers.length; i++) {
                System.out.println(headers[i]);
            }
            System.out.println("----------------------------------------");

            JAXBContext jc = JAXBContext.newInstance("test");
            Unmarshaller unmarshaller = jc.createUnmarshaller();
            StringBuffer xmlStr = new StringBuffer(EntityUtils.toString(entity));
            Object obj = unmarshaller.unmarshal(new StreamSource(new StringReader(xmlStr.toString())));
            System.out.println("breakpoint");

        }
        catch (Exception e) {
            e.printStackTrace();
        }
        finally {
            // When HttpClient instance is no longer needed,
            // shut down the connection manager to ensure
            // immediate deallocation of all system resources
            httpclient.getConnectionManager().shutdown();
        }
    }
}

But now I'm not sure what to do with that Object created on line 34. I have a folder full of classes created by JAXB from the XSD file, including an ObjectFactory class, but don't know what the next step should be.

Any tips are welcome. Back to more tutorials...