<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <LinearLayout android:orientation="horizontal" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content">
        <EditText android:id="@+id/symbol" android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:width="120dip"/>
        <Button android:id="@+id/addBtn" android:layout_width="wrap_content"
            android:layout_height="wrap_content" 
            android:text="@string/addBtnLbl"/>
    </LinearLayout>
    <LinearLayout android:orientation="horizontal" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content">
        <TextView android:layout_width="wrap_content" 
            android:layout_height="wrap_content" android:id="@+id/symList" />
        <Button android:id="@+id/dlBtn" android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:text="@string/dlBtnLbl"
        />
       </LinearLayout>
    <ListView android:id="@android:id/list" 
        android:layout_height="fill_parent" android:layout_width="fill_parent"
        android:layout_weight="1"
        />
</LinearLayout>

public class Main extends ListActivity {

    private int mode = XML; // default
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final EditText input = (EditText) findViewById(R.id.symbol);
        final TextView symbolsList = (TextView) findViewById(R.id.symList);
        final Button addButton = (Button) findViewById(R.id.addBtn);
        final Button dlButton = (Button) findViewById(R.id.dlBtn);
        addButton.setOnClickListener(new OnClickListener(){
            public void onClick(View v) {
                String newSymbol = input.getText().toString();
                if (symbolsList.getText() == null || 
                        symbolsList.getText().length() == 0){
                    symbolsList.setText(newSymbol);
                } else {
                    StringBuilder sb = 
                                  new StringBuilder(symbolsList.getText());
                    sb.append(",");
                    sb.append(newSymbol);
                    symbolsList.setText(sb.toString());
                }
                input.setText("");
            }
        });
        dlButton.setOnClickListener(new OnClickListener(){
            public void onClick(View v) {
                String symList = symbolsList.getText().toString();
                String[] symbols = symList.split(",");
                symbolsList.setText("");
                switch (mode){
                case JSON :
                    new StockJsonParser().execute(symbols);
                    break;
                case PROTOBUF :
                    new StockProtoBufParser().execute(symbols);
                    break;
                default :
                    new StockXmlParser().execute(symbols);
                    break;
                }
            }
        });
    }
}

public class StockBrokerServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, 
          HttpServletResponse response) throws IOException {
        String[] symbols = request.getParameterValues("stock");
        List<Stock> stocks = getStocks(symbols);
        String format = request.getParameter("format");
        String data = "";
        if (format == null || format.equalsIgnoreCase("xml")){
            data = Stock.toXml(stocks);
            response.setContentType("text/xml");    
        } else if (format.equalsIgnoreCase("json")){
            data = Stock.toJson(stocks);
            response.setContentType("application/json");
        } else if (format.equalsIgnoreCase("protobuf")){
            Portfolio p = Stock.toProtoBuf(stocks);
            response.setContentType("application/octet-stream");
            response.setContentLength(p.getSerializedSize());
            p.writeTo(response.getOutputStream());
            response.flushBuffer();
            return;
        }
        response.setContentLength(data.length());
        response.getWriter().print(data);
        response.flushBuffer();
        response.getWriter().close();
    }

    public List<Stock> getStocks(String... symbols) throws IOException{
        StringBuilder sb = new StringBuilder();
        for (String symbol : symbols){
            sb.append(symbol);
            sb.append('+');
        }
        sb.deleteCharAt(sb.length() - 1);
        String urlStr = 
                "http://finance.yahoo.com/d/quotes.csv?f=sb2n&s=" + 
                    sb.toString();
        URL url = new URL(urlStr);
        HttpURLConnection conn = 
                (HttpURLConnection) url.openConnection();
        BufferedReader reader = new BufferedReader(
                new InputStreamReader(conn.getInputStream()));
        String quote = reader.readLine();
        List<Stock> stocks = new ArrayList<Stock>(symbols.length);
        while (quote != null){
            String[] values = quote.split(",");
            Stock s = 
                      new Stock(values[0], values[2],
                           Double.parseDouble(values[1]));
            stocks.add(s);
            quote = reader.readLine();
        }
        return stocks;
    }
}

public class Stock {    
    private final String symbol;
    private final String name;
    private final double price;
      //getters and setters omitted

    public String toXml(){
        return "<stock><symbol>" + symbol + 
"</symbol><name><![CDATA[" +
            name + "]]></name><price>" + price + 
"</price></stock>";
    }

    public String toJson(){
        return "{ 'stock' : { 'symbol' : " +symbol +", 'name':" + name + 
            ", 'price': '" + price + "'}}";
    }

    public static String toXml(List<Stock> stocks){
        StringBuilder xml = new StringBuilder("<stocks>");
        for (Stock s : stocks){
            xml.append(s.toXml());
        }
        xml.append("</stocks>");
        return xml.toString();
    }

    public static String toJson(List<Stock> stocks){
        StringBuilder json = new StringBuilder("{'stocks' : [");
        for (Stock s : stocks){
            json.append(s.toJson());
            json.append(',');
        }
        json.deleteCharAt(json.length() - 1);
        json.append("]}");
        return json.toString();
    }
}

package stocks;

option java_package = "org.developerworks.stocks";

message Quote{
    required string symbol = 1;
    required string name = 2;
    required double price = 3;
}

message Portfolio{
    repeated Quote quote = 1;
}

public static Stocks.Portfolio toProtoBuf(List<Stock> stocks){
    List<Stocks.Quote> quotes = new ArrayList<Stocks.Quote>(stocks.size());
    for (Stock s : stocks){
        Quote q = 
            Quote.newBuilder()
                .setName(s.name)
                .setSymbol(s.symbol)
                .setPrice(s.price)
                .build();
        quotes.add(q);
    }
    return Portfolio.newBuilder().addAllQuote(quotes).build();
}

abstract class BaseStockParser extends AsyncTask<String, Integer, Stock[]>{
    String urlStr = "http://protostocks.appspot.com/stockbroker?format=";

    protected BaseStockParser(String format){
        urlStr += format;
    }

    private String makeUrlString(String... symbols) {
        StringBuilder sb = new StringBuilder(urlStr);
        for (int i=0;i<symbols.length;i++){
            sb.append("&stock=");
            sb.append(symbols[i]);
        }
        return sb.toString();
    }

    protected InputStream getData(String[] symbols) throws Exception{
        HttpClient client = new DefaultHttpClient();
        HttpGet request = new HttpGet(new URI(makeUrlString(symbols)));

        HttpResponse response = client.execute(request);
        return response.getEntity().getContent();
    }

    @Override
    protected void onPostExecute(Stock[] stocks){
        ArrayAdapter<Stock> adapter = 
            new ArrayAdapter<Stock>(Main.this, R.layout.stock, 
                      stocks );
        setListAdapter(adapter);
    }
}

private class StockXmlParser extends BaseStockParser{
    public StockXmlParser(){
        super("xml");
    }

    @Override
    protected Stock[] doInBackground(String... symbols) {
        ArrayList<Stock> stocks = new ArrayList<Stock>(symbols.length);
        try{
            ContentHandler handler = newHandler(stocks);
            Xml.parse(getData(symbols), Xml.Encoding.UTF_8, handler);
        } catch (Exception e){
            Log.e("DayTrader", "Exception getting XML data", e);
        }
        Stock[] array = new Stock[symbols.length];
        return stocks.toArray(array);
    }

    private ContentHandler newHandler(final ArrayList<Stock> stocks){
        RootElement root = new RootElement("stocks");
        Element stock = root.getChild("stock");
        final Stock currentStock = new Stock();
        stock.setEndElementListener(
            new EndElementListener(){
                public void end() {
                    stocks.add((Stock) currentStock.clone());
                }
            }
        );
        stock.getChild("name").setEndTextElementListener(
            new EndTextElementListener(){
                public void end(String body) {
                    currentStock.setName(body);
                }
            }
        );
        stock.getChild("symbol").setEndTextElementListener(
            new EndTextElementListener(){
                public void end(String body) {
                    currentStock.setSymbol(body);
                }
            }
        );
        stock.getChild("price").setEndTextElementListener(
            new EndTextElementListener(){
                public void end(String body) {
                            currentStock.setPrice(Double.parseDouble(body));
                }
            }
        );
        return root.getContentHandler();
    }
}

private class StockJsonParser extends BaseStockParser{
    public StockJsonParser(){
        super("json");
    }
    @Override
    protected Stock[] doInBackground(String... symbols) {
        Stock[] stocks = new Stock[symbols.length];
        try{
            StringBuilder json = new StringBuilder();
            BufferedReader reader = 
                new BufferedReader(
                            new InputStreamReader(getData(symbols)));
            String line = reader.readLine();
            while (line != null){
                json.append(line);
                line = reader.readLine();
            }
            JSONObject jsonObj = new JSONObject(json.toString());
            JSONArray stockArray = jsonObj.getJSONArray("stocks");
            for (int i=0;i<stocks.length;i++){
                JSONObject object = 
                    stockArray.getJSONObject(i).getJSONObject("stock");
                stocks[i] = new Stock(object.getString("symbol"), 
                        object.getString("name"), 
                        object.getDouble("price"));
            }
        } catch (Exception e){
            Log.e("DayTrader", "Exception getting JSON data", e);
        }
        return stocks;
    }
}

private class StockProtoBufParser extends BaseStockParser{
    public StockProtoBufParser(){
        super("protobuf");
    }

    @Override
    protected Stock[] doInBackground(String... symbols) {
        Stock[] stocks = new Stock[symbols.length];
        try{
            Stocks.Portfolio portfolio = 
                Stocks.Portfolio.parseFrom(getData(symbols));
            for (int i=0;i<symbols.length;i++){
                stocks[i] = Stock.fromQuote(portfolio.getQuote(i));
            }
        } catch (Exception e){
            Log.e("DayTrader", "Exception getting ProtocolBuffer data", e);
        }
        return stocks;
    }
}