I'm following a guid in Head First Android Development, and I can't seem to get this part right. The code is supposed to get a image with title and description from a Nasa RSS feed, but it does not retrieve the image. Any help would be awesome :)
package com.olshausen.nasadailyimage;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import android.os.Bundle;
import android.widget.ImageView;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Menu;
import android.widget.TextView;
public class DailyImage extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_daily_image);
IotdHandler handler = new IotdHandler ();
handler.processFeed();
resetDisplay (handler.getTitle(), handler.getDate(), handler.getImage(), handler.getDescription());
}
public class IotdHandler extends DefaultHandler {
private String url = "http://www.nasa.gov/rss/image_of_the_day.rss";
private boolean inUrl = false;
private boolean inTitle = false;
private boolean inDescription = false;
private boolean inItem = false;
private boolean inDate = false;
private Bitmap image = null;
private String title = null;
private StringBuffer description = new StringBuffer();
private String date = null;
public void processFeed() {
try {
SAXParserFactory factory =
SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLReader reader = parser.getXMLReader();
reader.setContentHandler(this);
InputStream inputStream = new URL(url).openStream();
reader.parse(new InputSource(inputStream));
} catch (Exception e) { }
}
private Bitmap getBitmap(String url) {
try {
HttpURLConnection connection = (HttpURLConnection)new URL(url).openConnection();
connection.setDoInput(true);
connection.connect();
InputStream input = connection.getInputStream();
Bitmap bilde = BitmapFactory.decodeStream(input);
input.close();
return bilde;
} catch (IOException ioe) { return null; }
}
public void startElement(String url, String localName, String qName, Attributes attributes) throws SAXException {
if (localName.endsWith(".jpg")) { inUrl = true; }
else { inUrl = false; }
if (localName.startsWith("item")) { inItem = true; }
else if (inItem) {
if (localName.equals("title")) { inTitle = true; }
else { inTitle = false; }
if (localName.equals("description")) { inDescription = true; }
else { inDescription = false; }
if (localName.equals("pubDate")) { inDate = true; }
else { inDate = false; }
}
}
public void characters(char ch[], int start, int length) { String chars = new String(ch).substring(start, start + length);
if (inUrl && url == null) { image = getBitmap(chars); }
if (inTitle && title == null) { title = chars; }
if (inDescription) { description.append(chars); }
if (inDate && date == null) { date = chars; }
}
public Bitmap getImage() { return image; }
public String getTitle() { return title; }
public StringBuffer getDescription() { return description; }
public String getDate() { return date; }
}
private void resetDisplay (String title, String date, Bitmap image, StringBuffer description) {
TextView titleView = (TextView) findViewById (R.id.image_title);
titleView.setText(title);
TextView dateView = (TextView) findViewById(R.id.image_date);
dateView.setText(date);
ImageView imageView = (ImageView) findViewById (R.id.image_display);
imageView.setImageBitmap(image);
TextView descriptionView = (TextView) findViewById (R.id.image_description);
descriptionView.setText(description);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_daily_image, menu);
return true;
}
}
I must honestly say that I copied most of this code without checking it, the parser was "ready bake code", so its not really what is supposed to be tought in this chapter :)
Try using a framework instead - even the simplistic built-in framework is better than that horrible kludge you found.
This example uses the RootElement / Element and associated listeners from the android.sax package.
class NasaParser {
private String mTitle;
private String mDescription;
private String mDate;
private String mImageUrl;
public void parse(InputStream is) throws IOException, SAXException {
RootElement rss = new RootElement("rss");
Element channel = rss.requireChild("channel");
Element item = channel.requireChild("item");
item.setElementListener(new ElementListener() {
public void end() {
onItem(mTitle, mDescription, mDate, mImageUrl);
}
public void start(Attributes attributes) {
mTitle = mDescription = mDate = mImageUrl = null;
}
});
item.getChild("title").setEndTextElementListener(new EndTextElementListener() {
public void end(String body) {
mTitle = body;
}
});
item.getChild("description").setEndTextElementListener(new EndTextElementListener() {
public void end(String body) {
mDescription = body;
}
});
item.getChild("pubDate").setEndTextElementListener(new EndTextElementListener() {
public void end(String body) {
mDate = body;
}
});
item.getChild("enclosure").setStartElementListener(new StartElementListener() {
public void start(Attributes attributes) {
mImageUrl = attributes.getValue("", "url");
}
});
Xml.parse(is, Encoding.UTF_8, rss.getContentHandler());
}
public void onItem(String title, String description, String date, String imageUrl) {
// This is where you handle the item in the RSS channel, etc. etc.
// (Left as an exercise for the reader)
System.out.println("title=" + title);
System.out.println("description=" + description);
System.out.println("date=" + date);
// This needs to be downloaded for instance
System.out.println("imageUrl=" + imageUrl);
}
}