Android Open Source - rest_loader_tutorial R E S T Loader Activity

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License

The source code is released under:

Copyright (C) 2011 Neil Goodman Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Softw...

Java Source Code

package net.neilgoodman.android.restloadertutorial;
/* w  ww . j  a  va 2  s . c  om*/
import java.util.ArrayList;
import java.util.List;

import net.neilgoodman.android.restloadertutorial.loader.RESTLoader;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONTokener;

import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.app.ListFragment;
import android.support.v4.app.LoaderManager.LoaderCallbacks;
import android.support.v4.content.Loader;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.Toast;

/**
 * A simple ListActivity that display Tweets that contain the word
 * Android in them.
 * 
 * @author Neil Goodman
 *
 */
public class RESTLoaderActivity extends FragmentActivity implements LoaderCallbacks<RESTLoader.RESTResponse> {
    private static final String TAG = RESTLoaderActivity.class.getName();
    
    private static final int LOADER_TWITTER_SEARCH = 0x1;
    
    private static final String ARGS_URI    = "net.neilgoodman.android.restloadertutorial.ARGS_URI";
    private static final String ARGS_PARAMS = "net.neilgoodman.android.restloadertutorial.ARGS_PARAMS";
    
    private ArrayAdapter<String> mAdapter;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_rest_loader);
        
        // Since we are using the Android Compatibility library
        // we have to use FragmentActivity. So, we use ListFragment
        // to get the same functionality as ListActivity.
        FragmentManager fm = getSupportFragmentManager();
        
        
        ListFragment list =(ListFragment) fm.findFragmentById(R.id.fragment_content); 
        if (list == null){
          list = new ListFragment();
          FragmentTransaction ft = fm.beginTransaction();
          ft.add(R.id.fragment_content, list);
          ft.commit();
        }
        
        mAdapter = new ArrayAdapter<String>(this, R.layout.item_label_list);
        
        // Let's set our list adapter to a simple ArrayAdapter.
        list.setListAdapter(mAdapter);
        
        // This is our REST action.
        Uri twitterSearchUri = Uri.parse("http://search.twitter.com/search.json");
        
        // Here we are going to place our REST call parameters. Note that
        // we could have just used Uri.Builder and appendQueryParameter()
        // here, but I wanted to illustrate how to use the Bundle params.
        Bundle params = new Bundle();
        params.putString("q", "android");
        
        // These are the loader arguments. They are stored in a Bundle because
        // LoaderManager will maintain the state of our Loaders for us and
        // reload the Loader if necessary. This is the whole reason why
        // we have even bothered to implement RESTLoader.
        Bundle args = new Bundle();
        args.putParcelable(ARGS_URI, twitterSearchUri);
        args.putParcelable(ARGS_PARAMS, params);
        
        // Initialize the Loader.
        getSupportLoaderManager().initLoader(LOADER_TWITTER_SEARCH, args, this);
    }

    @Override
    public Loader<RESTLoader.RESTResponse> onCreateLoader(int id, Bundle args) {
        if (args != null && args.containsKey(ARGS_URI) && args.containsKey(ARGS_PARAMS)) {
            Uri    action = args.getParcelable(ARGS_URI);
            Bundle params = args.getParcelable(ARGS_PARAMS);
            
            return new RESTLoader(this, RESTLoader.HTTPVerb.GET, action, params);
        }
        
        return null;
    }

    @Override
    public void onLoadFinished(Loader<RESTLoader.RESTResponse> loader, RESTLoader.RESTResponse data) {
        int    code = data.getCode();
        String json = data.getData();
        
        // Check to see if we got an HTTP 200 code and have some data.
        if (code == 200 && !json.equals("")) {
            
            // For really complicated JSON decoding I usually do my heavy lifting
            // Gson and proper model classes, but for now let's keep it simple
            // and use a utility method that relies on some of the built in
            // JSON utilities on Android.
            List<String> tweets = getTweetsFromJson(json);
            
            // Load our list adapter with our Tweets.
            mAdapter.clear();
            for (String tweet : tweets) {
                mAdapter.add(tweet);
            }
        }
        else {
            Toast.makeText(this, "Failed to load Twitter data. Check your internet settings.", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onLoaderReset(Loader<RESTLoader.RESTResponse> loader) {
    }
    
    private static List<String> getTweetsFromJson(String json) {
        ArrayList<String> tweetList = new ArrayList<String>();
        
        try {
            JSONObject tweetsWrapper = (JSONObject) new JSONTokener(json).nextValue();
            JSONArray  tweets        = tweetsWrapper.getJSONArray("results");
            
            for (int i = 0; i < tweets.length(); i++) {
                JSONObject tweet = tweets.getJSONObject(i);
                tweetList.add(tweet.getString("text"));
            }
        }
        catch (JSONException e) {
            Log.e(TAG, "Failed to parse JSON.", e);
        }
        
        return tweetList;
    }
}

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