XmlParsing Using XmlPullParser in Android Studio

Introduction

 

In this article, you will learn about XML parsing with the pull parser

 

XML Parsing

 

XML parsing is a process of converting data from a server in a machine-readable form.

 

XML pull parser

 

The XML pull parser is an interface that defines the parsing functionality. It provides two key methods next() that provide access to high-level parsing events. The current event state of the parser can be determined by the geteventType() method. Initially, the parser lies in the START_DOCUMENT state.

 

The following are the events seen by next():

• START_TAG: 
  an XML start tag was read.
  
  
• Text:
  Text content was read. The text content was retrieved using the getText() method.
  
  
• END_TAG:
  A tag was read.
  
  
• END_DOCUMENT:
  No more events are available.

Step 1

 

Create an XML file and write this:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">
    <ListView

            android:id="@android:id/list"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content"/>

</RelativeLayout>

Step 2

 

Create a Java file MainActivity.java and write this:

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;

import java.io.IOException;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;

public class MainActivity extends ListActivity {

    private static String BASE_URL = "http://maps.googleapis.com/maps/api/geocode/xml?address=NewDelhi&sensor=false";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        (new ProgressTask(MainActivity.this)).execute();
    }
@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public class ProgressTask extends AsyncTask<String, Void, Boolean> {

        private ProgressDialog dialog;
        private Context context;

        public ProgressTask(ListActivity activity) {
            Log.i("1", "Called");
            context = activity;

            dialog = new ProgressDialog(context);
        }
        protected void onPreExecute() {
            this.dialog.setMessage("Progress start");
            this.dialog.show();
        }
        @Override
        protected void onPostExecute(final Boolean success) {
            if (dialog.isShowing()) {
                dialog.dismiss();
            }
       }
         protected Boolean doInBackground(final String... args) {
            String xml = getXmlFromUrl(BASE_URL);
 //            useParserType1(xml);
            useParserType2(xml);
            return null;
       }
     }

   //DOM Parser
    public void useParserType1(String xml){
        XmlParsingType1 parser = new XmlParsingType1();
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList GeocodeResponse = doc.getElementsByTagName("location");

        for (int i = 0; i < GeocodeResponse.getLength(); i++) {
            Element e = (Element) GeocodeResponse.item(i);
            Log.i("xml", parser.getValue(e,"lat"));
            Log.i("xml", parser.getValue(e,"lng"));
        }
    }

    //XmlPull Parser
    public void useParserType2(String xml){
        try{
        Boolean flagLocation = false;
        Boolean flagLatitude = false;
        Boolean flagLongitude = false;
        XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
        factory.setNamespaceAware(true);
        XmlPullParser xpp = factory.newPullParser();

        xpp.setInput(new StringReader(xml));
        int eventType = xpp.getEventType();
        while (eventType != XmlPullParser.END_DOCUMENT) {
            if(eventType == XmlPullParser.START_DOCUMENT) {

            } else if(eventType == XmlPullParser.END_DOCUMENT) {

            } else if(eventType == XmlPullParser.START_TAG) {

                if (xpp.getName().equalsIgnoreCase("location")) flagLocation=true;
                if (flagLocation && xpp.getName().equalsIgnoreCase("lat")) flagLatitude=true;
                if (flagLocation && xpp.getName().equalsIgnoreCase("lng")) flagLongitude=true;

            } else if(eventType == XmlPullParser.END_TAG) {

                if (xpp.getName().equalsIgnoreCase("location")) flagLocation=false;
                if (flagLocation && xpp.getName().equalsIgnoreCase("lat")) flagLatitude=false;
                if (flagLocation && xpp.getName().equalsIgnoreCase("lng")) flagLongitude=false;

            } else if(eventType == XmlPullParser.TEXT) {


                if (flagLatitude)
                    Log.i("Latitude: ", xpp.getText());
                if (flagLongitude)
                    Log.i("Longitude: ", xpp.getText());
            }
            eventType = xpp.next();
        }

        }catch (XmlPullParserException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
    }
    public String getXmlFromUrl(String url) {
        String xml = null;

        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity);

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // return XML
        return xml;
    }

}

Step 3

 

Create another Java class file XMLParser.java and write this:

import android.util.Log;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.io.StringReader;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

/**
 * Created by naveen on 19/06/13.
 */
public class XmlParsingType1 {

    public Document getDomElement(String xml){
        Document doc = null;
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

        try {

            DocumentBuilder db = dbf.newDocumentBuilder();

            InputSource is = new InputSource();
            is.setCharacterStream(new StringReader(xml));
            doc = db.parse(is);

        } catch (ParserConfigurationException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (SAXException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        } catch (IOException e) {
            Log.e("Error: ", e.getMessage());
            return null;
        }
        // return DOM
        return doc;
    }

    public String getValue(Element item, String str) {
        NodeList n = item.getElementsByTagName(str);
        return this.getElementValue(n.item(0));
    }

    public final String getElementValue( Node elem ) {
        Node child;
        if( elem != null){
            if (elem.hasChildNodes()){
                for( child = elem.getFirstChild(); child != null; child = child.getNextSibling() ){
                    if( child.getNodeType() == Node.TEXT_NODE  ){
                        return child.getNodeValue();
                    }
                }
            }
        }
        return "";
    }
}

Output

 

 

See Logcat