samples/training/threadsample/src/com/example/android/threadsample/RSSPullService.java - platform/development - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.example.android.threadsample;

 import android.app.IntentService;
 import android.content.ContentValues;
 import android.content.Intent;
 import android.database.Cursor;

 import org.apache.http.HttpStatus;
 import org.xmlpull.v1.XmlPullParserException;

 import java.io.IOException;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.util.Date;
 import java.util.Vector;

 /**
  * This service pulls RSS content from a web site URL contained in the incoming Intent (see
  * onHandleIntent()). As it runs, it broadcasts its status using LocalBroadcastManager; any
  * component that wants to see the status should implement a subclass of BroadcastReceiver and
  * register to receive broadcast Intents with category = CATEGORY_DEFAULT and action
  * Constants.BROADCAST_ACTION.
  *
  */
 public class RSSPullService extends IntentService {
     // Used to write to the system log from this class.
     public static final String LOG_TAG = "RSSPullService";

     // Defines and instantiates an object for handling status updates.
     private BroadcastNotifier mBroadcaster = new BroadcastNotifier(this);

     /**
      * An IntentService must always have a constructor that calls the super constructor. The
      * string supplied to the super constructor is used to give a name to the IntentService's
      * background thread.
      */
     public RSSPullService() {

         super("RSSPullService");
     }

     /**
      * In an IntentService, onHandleIntent is run on a background thread.  As it
      * runs, it broadcasts its current status using the LocalBroadcastManager.
      * @param workIntent The Intent that starts the IntentService. This Intent contains the
      * URL of the web site from which the RSS parser gets data.
      */
     @Override
     protected void onHandleIntent(Intent workIntent) {
         // Gets a URL to read from the incoming Intent's "data" value
         String localUrlString = workIntent.getDataString();

         // Creates a projection to use in querying the modification date table in the provider.
         final String[] dateProjection = new String[]
         {
             DataProviderContract.ROW_ID,
             DataProviderContract.DATA_DATE_COLUMN
         };

         // A URL that's local to this method
         URL localURL;

         // A cursor that's local to this method.
         Cursor cursor = null;

         /*
          * A block that tries to connect to the Picasa featured picture URL passed as the "data"
          * value in the incoming Intent. The block throws exceptions (see the end of the block).
          */
         try {

             // Convert the incoming data string to a URL.
             localURL = new URL(localUrlString);

             /*
              * Tries to open a connection to the URL. If an IO error occurs, this throws an
              * IOException
              */
             URLConnection localURLConnection = localURL.openConnection();

             // If the connection is an HTTP connection, continue
             if ((localURLConnection instanceof HttpURLConnection)) {

                 // Broadcasts an Intent indicating that processing has started.
                 mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_STARTED);

                 // Casts the connection to a HTTP connection
                 HttpURLConnection localHttpURLConnection = (HttpURLConnection) localURLConnection;

                 // Sets the user agent for this request.
                 localHttpURLConnection.setRequestProperty("User-Agent", Constants.USER_AGENT);

                 /*
                  * Queries the content provider to see if this URL was read previously, and when.
                  * The content provider throws an exception if the URI is invalid.
                  */
                 cursor = getContentResolver().query(
                         DataProviderContract.DATE_TABLE_CONTENTURI,
                         dateProjection,
                         null,
                         null,
                         null);

                 // Flag to indicate that new metadata was retrieved
                 boolean newMetadataRetrieved;

                 /*
                  * Tests to see if the table contains a modification date for the URL
                  */
                 if (null != cursor && cursor.moveToFirst()) {

                     // Find the URL's last modified date in the content provider
                     long storedModifiedDate =
                             cursor.getLong(cursor.getColumnIndex(
                                     DataProviderContract.DATA_DATE_COLUMN)
                             )
                     ;

                     /*
                      * If the modified date isn't 0, sets another request property to ensure that
                      * data is only downloaded if it has changed since the last recorded
                      * modification date. Formats the date according to the RFC1123 format.
                      */
                     if (0 != storedModifiedDate) {
                         localHttpURLConnection.setRequestProperty(
                                 "If-Modified-Since",
                                 org.apache.http.impl.cookie.DateUtils.formatDate(
                                         new Date(storedModifiedDate),
                                         org.apache.http.impl.cookie.DateUtils.PATTERN_RFC1123));
                     }

                     // Marks that new metadata does not need to be retrieved
                     newMetadataRetrieved = false;

                 } else {

                     /*
                      * No modification date was found for the URL, so newmetadata has to be
                      * retrieved.
                      */
                     newMetadataRetrieved = true;

                 }

                 // Reports that the service is about to connect to the RSS feed
                 mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_CONNECTING);

                 // Gets a response code from the RSS server
                 int responseCode = localHttpURLConnection.getResponseCode();

                 switch (responseCode) {

                     // If the response is OK
                     case HttpStatus.SC_OK:

                         // Gets the last modified data for the URL
                         long lastModifiedDate = localHttpURLConnection.getLastModified();

                         // Reports that the service is parsing
                         mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_PARSING);

                         /*
                          * Instantiates a pull parser and uses it to parse XML from the RSS feed.
                          * The mBroadcaster argument send a broadcaster utility object to the
                          * parser.
                          */
                         RSSPullParser localPicasaPullParser = new RSSPullParser();

                         localPicasaPullParser.parseXml(
                             localURLConnection.getInputStream(),
                             mBroadcaster);

                         // Reports that the service is now writing data to the content provider.
                         mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_WRITING);

                         // Gets image data from the parser
                         Vector<ContentValues> imageValues = localPicasaPullParser.getImages();

                         // Stores the number of images
                         int imageVectorSize = imageValues.size();

                         // Creates one ContentValues for each image
                         ContentValues[] imageValuesArray = new ContentValues[imageVectorSize];

                         imageValuesArray = imageValues.toArray(imageValuesArray);

                         /*
                          * Stores the image data in the content provider. The content provider
                          * throws an exception if the URI is invalid.
                          */
                         getContentResolver().bulkInsert(
                                 DataProviderContract.PICTUREURL_TABLE_CONTENTURI, imageValuesArray);

                         // Creates another ContentValues for storing date information
                         ContentValues dateValues = new ContentValues();

                         // Adds the URL's last modified date to the ContentValues
                         dateValues.put(DataProviderContract.DATA_DATE_COLUMN, lastModifiedDate);

                         if (newMetadataRetrieved) {

                             // No previous metadata existed, so insert the data
                             getContentResolver().insert(
                                 DataProviderContract.DATE_TABLE_CONTENTURI,
                                 dateValues
                             );

                         } else {

                             // Previous metadata existed, so update it.
                             getContentResolver().update(
                                     DataProviderContract.DATE_TABLE_CONTENTURI,
                                     dateValues,
                                     DataProviderContract.ROW_ID + "=" +
                                             cursor.getString(cursor.getColumnIndex(
                                                             DataProviderContract.ROW_ID)), null);
                         }
                         break;

                 }

                 // Reports that the feed retrieval is complete.
                 mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_COMPLETE);
             }

         // Handles possible exceptions
         } catch (MalformedURLException localMalformedURLException) {

             localMalformedURLException.printStackTrace();

         } catch (IOException localIOException) {

             localIOException.printStackTrace();

         } catch (XmlPullParserException localXmlPullParserException) {

             localXmlPullParserException.printStackTrace();

         } finally {

             // If an exception occurred, close the cursor to prevent memory leaks.
             if (null != cursor) {
                 cursor.close();
             }
         }
     }

 }
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.example.android.threadsample;

	import android.app.IntentService;
	import android.content.ContentValues;
	import android.content.Intent;
	import android.database.Cursor;

	import org.apache.http.HttpStatus;
	import org.xmlpull.v1.XmlPullParserException;

	import java.io.IOException;
	import java.net.HttpURLConnection;
	import java.net.MalformedURLException;
	import java.net.URL;
	import java.net.URLConnection;
	import java.util.Date;
	import java.util.Vector;

	/**
	* This service pulls RSS content from a web site URL contained in the incoming Intent (see
	* onHandleIntent()). As it runs, it broadcasts its status using LocalBroadcastManager; any
	* component that wants to see the status should implement a subclass of BroadcastReceiver and
	* register to receive broadcast Intents with category = CATEGORY_DEFAULT and action
	* Constants.BROADCAST_ACTION.
	*
	*/
	public class RSSPullService extends IntentService {
	// Used to write to the system log from this class.
	public static final String LOG_TAG = "RSSPullService";

	// Defines and instantiates an object for handling status updates.
	private BroadcastNotifier mBroadcaster = new BroadcastNotifier(this);

	/**
	* An IntentService must always have a constructor that calls the super constructor. The
	* string supplied to the super constructor is used to give a name to the IntentService's
	* background thread.
	*/
	public RSSPullService() {

	super("RSSPullService");
	}

	/**
	* In an IntentService, onHandleIntent is run on a background thread. As it
	* runs, it broadcasts its current status using the LocalBroadcastManager.
	* @param workIntent The Intent that starts the IntentService. This Intent contains the
	* URL of the web site from which the RSS parser gets data.
	*/
	@Override
	protected void onHandleIntent(Intent workIntent) {
	// Gets a URL to read from the incoming Intent's "data" value
	String localUrlString = workIntent.getDataString();

	// Creates a projection to use in querying the modification date table in the provider.
	final String[] dateProjection = new String[]
	{
	DataProviderContract.ROW_ID,
	DataProviderContract.DATA_DATE_COLUMN
	};

	// A URL that's local to this method
	URL localURL;

	// A cursor that's local to this method.
	Cursor cursor = null;

	/*
	* A block that tries to connect to the Picasa featured picture URL passed as the "data"
	* value in the incoming Intent. The block throws exceptions (see the end of the block).
	*/
	try {

	// Convert the incoming data string to a URL.
	localURL = new URL(localUrlString);

	/*
	* Tries to open a connection to the URL. If an IO error occurs, this throws an
	* IOException
	*/
	URLConnection localURLConnection = localURL.openConnection();

	// If the connection is an HTTP connection, continue
	if ((localURLConnection instanceof HttpURLConnection)) {

	// Broadcasts an Intent indicating that processing has started.
	mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_STARTED);

	// Casts the connection to a HTTP connection
	HttpURLConnection localHttpURLConnection = (HttpURLConnection) localURLConnection;

	// Sets the user agent for this request.
	localHttpURLConnection.setRequestProperty("User-Agent", Constants.USER_AGENT);

	/*
	* Queries the content provider to see if this URL was read previously, and when.
	* The content provider throws an exception if the URI is invalid.
	*/
	cursor = getContentResolver().query(
	DataProviderContract.DATE_TABLE_CONTENTURI,
	dateProjection,
	null,
	null,
	null);

	// Flag to indicate that new metadata was retrieved
	boolean newMetadataRetrieved;

	/*
	* Tests to see if the table contains a modification date for the URL
	*/
	if (null != cursor && cursor.moveToFirst()) {

	// Find the URL's last modified date in the content provider
	long storedModifiedDate =
	cursor.getLong(cursor.getColumnIndex(
	DataProviderContract.DATA_DATE_COLUMN)
	)
	;

	/*
	* If the modified date isn't 0, sets another request property to ensure that
	* data is only downloaded if it has changed since the last recorded
	* modification date. Formats the date according to the RFC1123 format.
	*/
	if (0 != storedModifiedDate) {
	localHttpURLConnection.setRequestProperty(
	"If-Modified-Since",
	org.apache.http.impl.cookie.DateUtils.formatDate(
	new Date(storedModifiedDate),
	org.apache.http.impl.cookie.DateUtils.PATTERN_RFC1123));
	}

	// Marks that new metadata does not need to be retrieved
	newMetadataRetrieved = false;

	} else {

	/*
	* No modification date was found for the URL, so newmetadata has to be
	* retrieved.
	*/
	newMetadataRetrieved = true;

	}

	// Reports that the service is about to connect to the RSS feed
	mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_CONNECTING);

	// Gets a response code from the RSS server
	int responseCode = localHttpURLConnection.getResponseCode();

	switch (responseCode) {

	// If the response is OK
	case HttpStatus.SC_OK:

	// Gets the last modified data for the URL
	long lastModifiedDate = localHttpURLConnection.getLastModified();

	// Reports that the service is parsing
	mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_PARSING);

	/*
	* Instantiates a pull parser and uses it to parse XML from the RSS feed.
	* The mBroadcaster argument send a broadcaster utility object to the
	* parser.
	*/
	RSSPullParser localPicasaPullParser = new RSSPullParser();

	localPicasaPullParser.parseXml(
	localURLConnection.getInputStream(),
	mBroadcaster);

	// Reports that the service is now writing data to the content provider.
	mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_WRITING);

	// Gets image data from the parser
	Vector<ContentValues> imageValues = localPicasaPullParser.getImages();

	// Stores the number of images
	int imageVectorSize = imageValues.size();

	// Creates one ContentValues for each image
	ContentValues[] imageValuesArray = new ContentValues[imageVectorSize];

	imageValuesArray = imageValues.toArray(imageValuesArray);

	/*
	* Stores the image data in the content provider. The content provider
	* throws an exception if the URI is invalid.
	*/
	getContentResolver().bulkInsert(
	DataProviderContract.PICTUREURL_TABLE_CONTENTURI, imageValuesArray);

	// Creates another ContentValues for storing date information
	ContentValues dateValues = new ContentValues();

	// Adds the URL's last modified date to the ContentValues
	dateValues.put(DataProviderContract.DATA_DATE_COLUMN, lastModifiedDate);

	if (newMetadataRetrieved) {

	// No previous metadata existed, so insert the data
	getContentResolver().insert(
	DataProviderContract.DATE_TABLE_CONTENTURI,
	dateValues
	);

	} else {

	// Previous metadata existed, so update it.
	getContentResolver().update(
	DataProviderContract.DATE_TABLE_CONTENTURI,
	dateValues,
	DataProviderContract.ROW_ID + "=" +
	cursor.getString(cursor.getColumnIndex(
	DataProviderContract.ROW_ID)), null);
	}
	break;

	}

	// Reports that the feed retrieval is complete.
	mBroadcaster.broadcastIntentWithState(Constants.STATE_ACTION_COMPLETE);
	}

	// Handles possible exceptions
	} catch (MalformedURLException localMalformedURLException) {

	localMalformedURLException.printStackTrace();

	} catch (IOException localIOException) {

	localIOException.printStackTrace();

	} catch (XmlPullParserException localXmlPullParserException) {

	localXmlPullParserException.printStackTrace();

	} finally {

	// If an exception occurred, close the cursor to prevent memory leaks.
	if (null != cursor) {
	cursor.close();
	}
	}
	}

	}