stockmidlet.java

用于移动设备上的java虚拟机源代码

/*
 * @(#)StockMIDlet.java	1.37 02/10/08 @(#)
 *
 * Copyright (c) 1999-2001 Sun Microsystems, Inc.  All rights reserved.
 * PROPRIETARY/CONFIDENTIAL
 * Use is subject to license terms.
 */

package example.stock;

import javax.microedition.rms.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.io.*;
import java.io.*;
import java.util.Timer;
import java.util.TimerTask;

/**
 * <p>The MIDlet application class that we'll run for the Stock Demo.</p>
 *
 * @author  Jeffrey Bacon
 */
public class StockMIDlet extends MIDlet {

    /**
     * Since there is no support in MIDP/CLDC for floating point numbers,
     * and all of the stock data comes in the form ##.### (usually) then we
     * have to find a way to store the decimals as well as the integer part
     * of the quote data.  Multiplying by the OFFSET will shift the decimal
     * place far enough over to make the number an integer which we can
     * store.  Every time we retrieve quote data from our
     * <code>RecordStore</code> we
     * must make sure that we divide by the OFFSET to correctly display and
     * use the value we actually want.
     */
    private static int OFFSET = 10000; // each 0 is one decimal place

    /**
     * The <code>MIDlet</code>'s display object
     */
    Display display = null;

    /**
     * The <code>Ticker</code> that scrolls along the top of the screen
     */
    private Ticker stockTicker = null;

    /**
     * A <code>List</code> of stocks
     */
    private List choose       = null;

    /**
     * The Stock Tracker menu
     */
    private List view         = null;

    /**
     * The Main menu
     */
    private List menu         = null;

    /**
     * The Alert menu
     */
    private List alertList    = null;

    /**
     * The Settings menu
     */
    private List settingsList = null;

    /**
     * The 'What If?' <code>Form</code> upon which we enter our query data
     */
    private Form whatif       = null;

    /**
     * The <code>Form</code> to display the different update intervals settings
     */
    private Form updatesForm  = null;

    /**
     * Used to input a stock symbol
     */
    private TextBox stockSymbolBox = null;

    /**
     * Used to enter the price at which the user wishes to be alerted to the
     * stocks's value
     */
    private TextBox alertPriceBox  = null;

    /**
     * The original price the user purchased the stock at, used on the What If?
     * <code>Form</code>
     */
    private TextField origPurchPriceField = null;

    /**
     * The number of shares the users wishes to sell, used on the What If?
     * <code>Form</code>
     */
    private TextField numSharesField      = null;

    /**
     * Back <code>Command</code>
     */
    private static final Command BACK_COMMAND     = 
	new Command("Back", Command.BACK, 0);

    /**
     * Main Menu <code>Command</code>
     */
    private static final Command MAIN_MENU_COMMAND = 
	new Command("Main", Command.SCREEN, 1);

    /**
     * Done <code>Command</code>
     */
    private static final Command DONE_COMMAND     = 
	new Command("Done", Command.OK,     2);

    /**
     * Set <code>Command</code>
     */
    private static final Command SET_COMMAND      = 
	new Command("Set", Command.OK,     4);

    /**
     * Exit <code>Command</code>
     */
    private static final Command EXIT_COMMAND     = 
	new Command("Exit", Command.STOP, 5);

    /**
     * Calc <code>Command</code>
     */
    private static final Command CALC_COMMAND     = 
	new Command("Calc", Command.OK,     6);

    /**
     * About <code>Command</code>
     */
    private static final Command ABOUT_COMMAND    = 
	new Command("About", Command.HELP,   1);

    /**
     * The radio buttons for the update interval time
     */
    private ChoiceGroup updatesChoices = null;

    /**
     * A textual reference to the current menu that is displayed
     * onscreen to
     * allow the <code>StockCommandListener</code> to decide what
     * action to perform upon
     * execution of a command
     */
    private String currentMenu = null;

    /**
     * A reference to the stock that has been chosen from a list of stocks
     * onscreen.  Using this we can extract the correct stock's data from
     * the <code>StockDatabase</code>
     */
    private String stockSymbol = null;

    /**
     * The reference to the <code>StockDatabase</code> that stores
     * the stock data
     */
    private StockDatabase stocks = null;

    /**
     * The reference to the <code>AlertDatabase</code> that stores the alerts
     */
    private AlertDatabase alerts = null;

    /**
     * The server from which the quotes are downloaded
     *
     * NOTE: Currently, only the quote.yahoo.com server is supported
     */
    private String quoteServerURL = "http://quote.yahoo.com/d/quotes.csv?s=";

    /**
     * The format parameter for the quote server to retrieve stock data
     *
     * NOTE: Currently, only this format is supported
     */
    private String quoteFormat = "&f=slc1wop";

    /**
     * The proxy server that must be negotiated
     *
     * NOTE: Proxy server is optional and a blank string indicates that
     *       no proxy should be used
     */
    // Initial default but read from settings file on subsequent runs
    private String proxyURL = null;

    /**
     * The <code>Timer</code> object that refreshes the stock
     * quotes periodically
     */
    private Timer stockRefresh = null;

    /**
     * The <code>TimerTask</code> that the <code>Timer</code>
     * performs periodically.
     * It refreshes the stock quotes
     */
    private StockRefreshTask stockRefreshTask = null;

    /**
     * How often are the stocks' data updated off of the server?
     */
    // Initial default but read from settings file on subsequent runs
    private int refresh_interval = 900000; // 1000 = 1 second

    /**
     * <p>Default constructor that is called by the application
     * manager to create a new instance of this <code>MIDlet</code> after
     * which the <code>MIDlet</code> enters the <code>Paused</code> state.</p>
     */
    public StockMIDlet() {}

    /**
     * <p>This method is invoked when the <code>MIDlet</code> 
     * is ready to run and
     * starts/resumes execution after being in the <code>Paused</code>
     * state. The
     * <code>MIDlet</code> acquires any resources it needs, 
     * enters the
     * <code>Active</code> state and begins to perform its service, 
     * which in this
     * case means it displays the main menu on the screen.</p>
     *
     * <p>The method proceeds like so:</p>
     *  <li> open the <code>StockDatabase</code> and the 
     * <code>AlertDatabase</code></li>
     *  <li> read the settings data from the settings 
     * <code>RecordStore</code></li>
     *  <li> create the string to be scrolled across the <code>Ticker</code> on
     *       the top of the screens and instantiate the Ticker object using that
     *       string.  That string will be constructed of the names and prices of
     *       the stocks in our database</li>
     *  <li> get and store the <code>MIDlet</code>'s
     *  <code>Display</code> object</li>
     *  <li> create and show the main menu</li>
     *  <li> instantiate the <code>TimerTask</code> and <code>Timer</code> and
     *       associate the two setting the refresh interval to the value of
     *       the refresh_interval variable</li>
     *
     * @throws <code>MIDletStateChangeException</code> is thrown if the
     *         <code>MIDlet</code> cannot start now but might be able to
     *         start at a later time.
     * @see javax.microedition.midlet.MIDlet
     */
    public void startApp() throws MIDletStateChangeException {
        synchronized (this) {
            display = Display.getDisplay(this);
            
            // Open the Stocks file
            stocks = new StockDatabase();
            try {
                stocks.open("Stocks");
            } catch (Exception e) {
                try {
                    stocks.cleanUp("Stocks");
                } catch (Exception e2) {}
            }
            
            // Open the Alerts file
            alerts = new AlertDatabase();
            try {
                alerts.open("Alerts");
            } catch (Exception e) {
                try {
                    alerts.cleanUp("Alerts");
                } catch (Exception e2) {}
            }
            
            // Open the Settings file
            try {
                RecordStore settings = 
                    RecordStore.openRecordStore("Settings", true);
                refresh_interval = 
                    Integer.valueOf(new String(settings.getRecord(1)))
                    .intValue();
                settings.closeRecordStore();
                
                // No settings file existed
            } catch (Exception e) {
                refresh_interval = 900000;
            }
            
            // Make the ticker
            stockTicker = new Ticker(makeTickerString());
            
            // Create all the menus and forms
            origPurchPriceField = 
                new TextField("Original Purchase Price:",     "", 5,  
                              TextField.NUMERIC);
            numSharesField      = 
                new TextField("Number Of Shares:",            "", 9,  
                              TextField.NUMERIC);
            
            menu = new List("Stock Menu", Choice.IMPLICIT);
            menu.append("Stock Tracker", null);
            menu.append("What If?", null);
            menu.append("Alerts", null);
            menu.append("Settings", null);
            menu.addCommand(EXIT_COMMAND);
            menu.addCommand(ABOUT_COMMAND);
            menu.setCommandListener(new StockCommandListener());
            menu.setTicker(stockTicker);
            
            whatif = new Form("What If?");
            whatif.setTicker(stockTicker);
            whatif.append(origPurchPriceField);
            whatif.append(numSharesField);
            whatif.addCommand(BACK_COMMAND);
            whatif.addCommand(CALC_COMMAND);
            whatif.setCommandListener(new StockCommandListener());
            
            alertList = new List("Alert Menu", Choice.IMPLICIT);
            alertList.setTicker(stockTicker);
            alertList.append("Add", null);
            alertList.append("Remove", null);
            alertList.addCommand(BACK_COMMAND);
            alertList.setCommandListener(new StockCommandListener());
            
            settingsList = new List("Settings", Choice.IMPLICIT);
            settingsList.setTicker(stockTicker);
            settingsList.append("Updates", null);
            settingsList.append("Add Stock", null);
            settingsList.append("Remove Stock", null);
            settingsList.addCommand(BACK_COMMAND);
            settingsList.setCommandListener(new StockCommandListener());