gistfile1.java

package com.google.gwt.sample.stockwatcher.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.JsArray;

import com.google.gwt.http.client.URL;
import com.google.gwt.http.client.Request;
import com.google.gwt.http.client.RequestBuilder;
import com.google.gwt.http.client.RequestCallback;
import com.google.gwt.http.client.RequestException;
import com.google.gwt.http.client.Response;

import com.google.code.gwt.storage.client.Storage;
import com.google.code.gwt.storage.client.StorageEvent;
import com.google.code.gwt.storage.client.StorageEventHandler;

import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyPressEvent;
import com.google.gwt.event.dom.client.KeyPressHandler;

import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.Random;

import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.RootPanel;

import com.google.gwt.i18n.client.NumberFormat;
import com.google.gwt.i18n.client.DateTimeFormat;

import java.util.ArrayList;
import java.util.Date;
import java.util.Iterator;

public class StockWatcher implements EntryPoint {

    private static final int REFRESH_INTERVAL = 5000; // ms
    // Should be able to use GWT.getModuleBaseURL() but that returns a 404
    private static final String JSON_URL = "http://localhost/StockWatcher/war/stockPrices.php?q=";

    private VerticalPanel main_panel = new VerticalPanel();
    private FlexTable stocks_flex_table = new FlexTable();
    private HorizontalPanel add_panel = new HorizontalPanel();
    private TextBox new_symbol_text_box = new TextBox();
    private Button add_stock_button = new Button("Add");
    private Label last_updated_label = new Label();
    private ArrayList<String> stocks = new ArrayList<String>();
    private Storage local_storage = Storage.getLocalStorage();
    private Label error_msg_label = new Label();

    /**
     * Entry point method
     */
    public void onModuleLoad()
    {
        // Create table for stock data
        stocks_flex_table.setText(0, 0, "Symbol");
        stocks_flex_table.setText(0, 1, "Price");
        stocks_flex_table.setText(0, 2, "Change");
        stocks_flex_table.setText(0, 3, "Remove");

        // Add styles to elements in the stock list table
        stocks_flex_table.setCellPadding(6);
        stocks_flex_table.getRowFormatter().addStyleName(0, "watchListHeader");
        stocks_flex_table.addStyleName("watchList");
        stocks_flex_table.getCellFormatter().addStyleName(0, 1, "watchListNumericColumn");
        stocks_flex_table.getCellFormatter().addStyleName(0, 2, "watchListNumericColumn");
        stocks_flex_table.getCellFormatter().addStyleName(0, 3, "watchListRemoveColumn");

        // Assemble Add Stock panel
        add_panel.add(new_symbol_text_box);
        add_panel.add(add_stock_button);
        add_panel.addStyleName("addPanel");
        
        // Assemble Main panel
        error_msg_label.setStyleName("errorMessage");
        error_msg_label.setVisible(false);

        main_panel.add(error_msg_label);
        main_panel.add(stocks_flex_table);
        main_panel.add(add_panel);
        main_panel.add(last_updated_label);

        // Associate the Main panel with the HTML host page
        RootPanel.get("stockList").add(main_panel);
        
        // Move cursor focus to the input box
        new_symbol_text_box.setFocus(true);

        // Setup timer to refresh list automatically
        Timer refresh_timer = new Timer() {
            @Override
            public void run()
            {
                refreshWatchList();
            }
        };

        refresh_timer.scheduleRepeating(REFRESH_INTERVAL);

        // Listen for click events on the "Add" button
        add_stock_button.addClickHandler(new ClickHandler() 
        {
            public void onClick(ClickEvent event)
            {
                addStock();
            }
        });

        // Listen for keyboard events in the input box
        new_symbol_text_box.addKeyPressHandler(new KeyPressHandler()
        {
            public void onKeyPress(KeyPressEvent event)
            {
                if (event.getCharCode() == KeyCodes.KEY_ENTER)
                {
                    addStock();
                }
            }
        });

        readLocalStorage();
    }

    private void addStock()
    {
        final String symbol = new_symbol_text_box.getText().toUpperCase().trim();

        if (this.validateStock(symbol))
        {
            addStock(symbol, true);
        }
    }

    private void addStock(final String symbol,
                          boolean write_local_storage)
    {
        new_symbol_text_box.setFocus(true);
        new_symbol_text_box.setText("");

        // Add the stock to the table
        int row = stocks_flex_table.getRowCount();

        stocks.add(symbol);
        stocks_flex_table.setText(row, 0, symbol);
        stocks_flex_table.setWidget(row, 2, new Label());
        stocks_flex_table.getCellFormatter().addStyleName(0, 1, "watchListNumericColumn");
        stocks_flex_table.getCellFormatter().addStyleName(0, 2, "watchListNumericColumn");
        stocks_flex_table.getCellFormatter().addStyleName(0, 3, "watchListRemoveColumn");

        // Add the stock to localStorage
        if (!(local_storage == null))
        {
            if (write_local_storage)
                local_storage.setItem("row-" + (new Integer(row).toString()), symbol);
        }
        
        // Add a button to remove this stock from the table
        Button remove_stock_button = new Button("X");
        remove_stock_button.addStyleDependentName("remove");

        remove_stock_button.addClickHandler(new ClickHandler()
        {
            public void onClick(ClickEvent event)
            {
                int removed_index = stocks.indexOf(symbol);

                stocks.remove(removed_index);
                stocks_flex_table.removeRow(removed_index + 1);
            }
        });

        stocks_flex_table.setWidget(row, 3, remove_stock_button);

        // Get the stock price
        refreshWatchList();
    }

    private boolean validateStock(final String symbol)
    {
        // Stock code must be between 1 and 10 characters that are
        // numbers, letters, or dots.
        if (!symbol.matches("^[0-9A-Z\\.]{1,10}$"))
        {
            Window.alert("'" + symbol + "' is not a valid symbol.");
            new_symbol_text_box.selectAll();

            return false;
        }

        // Don't add the stock if it's already in the table
        if (stocks.contains(symbol))
            return false;

        return true;
    }

    // Refresh prices on list of stocks
    private void refreshWatchList()
    {
        if (stocks.size() == 0)
        {
            return;
        }

        String url = JSON_URL;

        // Append watch list stock symbols to query URL
        Iterator iter = stocks.iterator();

        while (iter.hasNext())
        {
            url += iter.next();

            if (iter.hasNext())
            {
                url += "+";
            }
        }

        url = URL.encode(url);

        // Send request to server and handle errors
        RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, url);

        try {
            Request request = builder.sendRequest(null, new RequestCallback()
            {
                public void onError(Request request, Throwable exception)
                {
                    displayError("Couldn't retrieve JSON");
                }
                public void onResponseReceived(Request request, Response response)
                {
                    if (200 == response.getStatusCode())
                    {
                        updateTable(asArrayOfStockData(response.getText()));
                    } else {
                        displayError("Couldn't retrieve JSON (" + response.getStatusText() + ")");
                    }
                }
            });
        } catch (RequestException e) {
            displayError("Couldn't retrieve JSON");
        }
    }

    /**
     * Update the Price and Change for all fields in the stock table
     *
     * @param prices Stock data for all rows
     */
    private void updateTable(JsArray<StockData> prices)
    {
        for (int i = 0; i < prices.length(); i++)
        {
            updateTable(prices.get(i));
        }

        // Display timestamp showing last refresh
        last_updated_label.setText("Last update: "
            + DateTimeFormat.getMediumDateTimeFormat().format(new Date()));

        // Clear any errors
        error_msg_label.setVisible(false);
    }

    /**
     * Update a single row in the stock table
     *
     * @param price Stock data for a single row
     */
    private void updateTable(StockData price)
    {
        // Make sure the stock is still in the stock table
        if (!stocks.contains(price.getSymbol()))
        {
            return;
        }

        int row = stocks.indexOf(price.getSymbol()) + 1;

        // Format the data in the Price and Change fields
        String price_text = NumberFormat.getFormat("#,##0.00").format(
            price.getPrice());
        NumberFormat change_format = NumberFormat.getFormat("+#,##0.00;-#,##0.00");
        String change_text = change_format.format(price.getChange());
        String change_percent_text = change_format.format(price.getChangePercent());

        // Populate the Price and Change fields with new data
        stocks_flex_table.setText(row, 1, price_text);
        Label change_widget = (Label)stocks_flex_table.getWidget(row, 2);
        change_widget.setText(change_text + " (" + change_percent_text + "%)");

        // Change color of text in the Change field based on it's value
        String change_style_name = "noChange";

        if (price.getChangePercent() < -0.1f)
        {
            change_style_name = "negativeChange";
        } else if (price.getChangePercent() > 0.1f) {
            change_style_name = "positiveChange";
        }

        change_widget.setStyleName(change_style_name);
    }

    /**
     * Read localStorage for row-N keys and push each out to the
     * stocks list
     */
    private void readLocalStorage()
    {
        for (int i = 0; i < local_storage.getLength(); i++)
        {
            String current_key = local_storage.key(i);
            final String symbol = local_storage.getItem(current_key);

            if (this.validateStock(symbol))
               this.addStock(symbol, false);
        }
    }

    /**
     * If can't get JSON, display error message
     *
     * @param error
     */
    private void displayError(String error)
    {
        error_msg_label.setText("Error: " + error);
        error_msg_label.setVisible(true);
    }

    /**
     * Convert the string of JSON into JavaScript object
     */
    private final native JsArray<StockData> asArrayOfStockData(String json) /*-{ return eval(json); }-*/;
}