addressbookmidlet.java

j2me开发的一些例子

/*
 * Copyright (c) 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
 */

package examples.addressbook;

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

/**
 * This MIDlet implements a simple address book with
 * the following functionality: browsing, entry,
 * deletion, and searching (both on device and over
 * the network).
 */
public class AddressBookMIDlet extends MIDlet
    implements CommandListener, ItemStateListener {

    private RecordStore addrBook;

    private static final int FN_LEN = 10;
    private static final int LN_LEN = 20;
    private static final int PN_LEN = 15;
    final private static int ERROR = 0;
    final private static int INFO = 1;

    private Display display;
    private Alert alert;
    private Command cmdAdd;
    private Command cmdBack;
    private Command cmdCancel;
    private Command cmdDial;
    private Command cmdExit;
    private Command cmdSelect;
    private Command cmdSearchNetwork;
    private Command cmdSearchLocal;
    private List mainScr;
    private String[] mainScrChoices = {"Search",
                                       "Add New",
                                       "Browse",
                                       "Options" };

    private Form searchScr;
    private TextField s_lastName;
    private TextField s_firstName;

    private Form entryScr;
    private TextField e_lastName;
    private TextField e_firstName;
    private TextField e_phoneNum;

    private List nameScr;
    private Vector phoneNums;

    private Form optionScr;
    private ChoiceGroup sortChoice;
    private TextBox dialScr;

    private int sortOrder = 1;

    /**
     * Public no-argument constructor. Called by the system to
     * instantiate our class. Caches reference to
     * the display, allocate commands, and tries to open
     * the address book.
     */
    public AddressBookMIDlet() {
        display = Display.getDisplay(this);

        cmdAdd = new Command("Add", Command.OK, 1);
        cmdBack = new Command("Back", Command.BACK, 2);
        cmdCancel = new Command("Cancel", Command.BACK, 2);
        cmdDial = new Command("Dial", Command.OK, 1);
        cmdExit = new Command("Exit", Command.EXIT, 2);
        cmdSelect = new Command("Select", Command.OK, 1);
        cmdSearchNetwork = new Command("Network",
                                       Command.SCREEN, 4);
        cmdSearchLocal = new Command("Local", Command.SCREEN, 3);

        alert = new Alert("", "", null, AlertType.INFO);
        alert.setTimeout(2000);

        try {
            addrBook = RecordStore.openRecordStore("TheAddressBook",
                                                true);
        } catch (RecordStoreException e) {
            addrBook = null;
        }
    }

    /**
     * Called by the system to start our MIDlet.
     * If the open of the address book fails, display
     * an alert and continue.
     *
     */
	protected void startApp() {
        if (addrBook == null) {
            displayAlert(ERROR,
                         "Could not open address book", null);
        } else {
            genMainScr();
        }
    }

    /**
     * Called by the system to pause our MIDlet.
     * No actions required by our MIDlet.
     */
    protected void pauseApp() {}

    /**
     * Called by the system to end our MIDlet.
     * No actions required by our MIDlet.
     */
    protected void destroyApp(boolean unconditional) {
        if (addrBook != null) {
            try {
                addrBook.closeRecordStore();
            } catch (Exception e) { }
        }
    }

    /**
     * Display an Alert on the screen
     *
	 * @param	type	One of the following: ERROR, INFO
	 * @param	msg		Message to display
	 * @param	s		screen to change to after displaying alert.
     *         if null, revert to main screen
     */
    private void displayAlert(int type, String msg, Screen s) {
        alert.setString(msg);

        switch (type) {
        case ERROR:
            alert.setTitle("Error!");
            alert.setType(AlertType.ERROR);
            break;
        case INFO:
            alert.setTitle("Info");
            alert.setType(AlertType.INFO);
            break;
        }
        display.setCurrent(alert,
                           s == null ? display.getCurrent() : s);
    }

    /**
     * Notify the system that we are exiting.
     */
    private void midletExit() {
        destroyApp(false);
        notifyDestroyed();
    }

    /**
     * Create the first screen of our MIDlet.
     * This screen is a list.
     */
    private Screen genMainScr() {
        if (mainScr == null) {
            mainScr = new List("Menu",
                               List.IMPLICIT,
                               mainScrChoices,
                               null);
            mainScr.addCommand(cmdSelect);
            mainScr.addCommand(cmdExit);
            mainScr.setCommandListener(this);
        }
        display.setCurrent(mainScr);
        return mainScr;
    }

    /**
     * Sort order option screen.
     * Allows us to set sort order to either sorting by
     * last name (default), or first name.
     */
    private Screen genOptionScr() {
        if (optionScr == null) {
            optionScr = new Form("Options");
            optionScr.addCommand(cmdBack);
            optionScr.setCommandListener(this);

            sortChoice = new ChoiceGroup("Sort by",
                                         Choice.EXCLUSIVE);
            sortChoice.append("First name", null);
            sortChoice.append("Last name", null);
            sortChoice.setSelectedIndex(sortOrder, true);
            optionScr.append(sortChoice);
            optionScr.setItemStateListener(this);
        }
        display.setCurrent(optionScr);
        return optionScr;
    }

    /**
     * Search screen.
     *
	 * Displays two <code>TextField</code>s: one for
     * first name, and one for last name.
     * These are used for searching the address book.
     *
     * @see AddressBookMIDlet#genNameScr
     */
    private Screen genSearchScr() {
        if (searchScr == null) {
            searchScr = new Form("Search");
            searchScr.addCommand(cmdBack);
            searchScr.addCommand(cmdSearchNetwork);
            searchScr.addCommand(cmdSearchLocal);
            searchScr.setCommandListener(this);
            s_firstName = new TextField("First name:", "",
                                        FN_LEN, TextField.ANY);
            s_lastName = new TextField("Last name:", "",
                                       LN_LEN, TextField.ANY);
            searchScr.append(s_firstName);
            searchScr.append(s_lastName);
        }

        s_firstName.delete(0, s_firstName.size());
        s_lastName.delete(0, s_lastName.size());
        display.setCurrent(searchScr);
        return searchScr;
    }

    /**
     * Name/Phone number entry screen
     *
	 * Displays three <code>TextField</code>s: one for
     * first name, one for last name, and one for phone number.
     * These are used to capture data to add to the address book.
     *
     * @see AddressBookMIDlet#addEntry
     */
    private Screen genEntryScr() {
        if (entryScr == null) {
            entryScr = new Form("Add new");
            entryScr.addCommand(cmdCancel);
            entryScr.addCommand(cmdAdd);
            entryScr.setCommandListener(this);

            e_firstName = new TextField("First name:", "",
                                        FN_LEN, TextField.ANY);
            e_lastName = new TextField("Last name:", "",
                                       LN_LEN, TextField.ANY);
            e_phoneNum = new TextField("Phone Number", "",
                                       PN_LEN, TextField.PHONENUMBER);
            entryScr.append(e_firstName);
            entryScr.append(e_lastName);
            entryScr.append(e_phoneNum);
        }

        e_firstName.delete(0, e_firstName.size());
        e_lastName.delete(0, e_lastName.size());
        e_phoneNum.delete(0, e_phoneNum.size());

        display.setCurrent(entryScr);
        return entryScr;
    }

    /**
     * Generates a list of first/last/phone numbers.
     * Can be called as a result of a browse command
     * (genBrowseScr) or a search command
     * (genSearchScr).
     *
     *  title  title of this screen (since it can be called
     *         from a browse or a search command.
     *  f      if not null, first name to search on
     *  l      if not null, last name to search on
     */
    private Screen genNameScr(String title,
                              String f,
                              String l,
                              boolean local) {
        SimpleComparator sc;
        SimpleFilter sf = null;
        RecordEnumeration re;
        phoneNums = null;

        if (local) {
            sc = new SimpleComparator(sortOrder == 0 ?
                         SimpleComparator.SORT_BY_FIRST_NAME :
                         SimpleComparator.SORT_BY_LAST_NAME);

            if (f != null || l != null) {
                sf = new SimpleFilter(f, l);
            }

            try {
                re = addrBook.enumerateRecords(sf, sc, false);
            } catch (Exception e) {
                displayAlert(ERROR, 
                    "Could not create enumeration: " + e, null);
                return null;
            }
        } else {
            re = new NetworkQuery(f,l, sortOrder);
        }

        nameScr = null;
        if (re.hasNextElement()) {
            nameScr = new List(title, List.IMPLICIT);
            nameScr.addCommand(cmdBack);
            nameScr.addCommand(cmdDial);
            nameScr.setCommandListener(this);
            phoneNums = new Vector(6);

            try {
                while (re.hasNextElement()) {
                    byte[] b = re.nextRecord();
                    String pn = SimpleRecord.getPhoneNum(b);
                    nameScr.append(SimpleRecord.getFirstName(b) +
                        " " + SimpleRecord.getLastName(b) +
                        " " + SimpleRecord.getPhoneNum(b), null);
                    phoneNums.addElement(pn);
                }
            } catch (Exception e) {
                displayAlert(ERROR,
                    "Error while building name list: " + e, null);
                return null;
            }
            display.setCurrent(nameScr);

        } else {
            displayAlert(INFO, "No names found", null);
        }

        return nameScr;
    }

    /**
     * Generate a screen with which to dial the phone.
     * Note: this may or may not be implemented
     * on a given implementation.
     */
    private void genDialScr() {
        dialScr =  new TextBox("Dialing",
                               (String)phoneNums.elementAt(
                                   nameScr.getSelectedIndex()),
                               PN_LEN,
                               TextField.PHONENUMBER);
        dialScr.addCommand(cmdCancel);
        dialScr.setCommandListener(this);
        display.setCurrent(dialScr);
    }

    /**
     * Add an entry to the address book.
     * Called after the user selects the addCmd
     * while in the genEntryScr screen.
     */
    private void addEntry() {
        String f = e_firstName.getString();
        String l = e_lastName.getString();
        String p = e_phoneNum.getString();

        byte[] b = SimpleRecord.createRecord(f,l,p);
        try {
            addrBook.addRecord(b, 0, b.length);
            displayAlert(INFO, "Record added", mainScr);
        } catch (RecordStoreException rse) {
            displayAlert(ERROR, "Could not add record" + rse, 
                         mainScr);
        }
    }

    /***
     * This method implements a state machine that drives the
     * MIDlet from one state (screen) to the next.
     */
    public void commandAction(Command c,
                              Displayable d) {
        if (d == mainScr) {
            // Handle main sceen
            if (c == cmdExit) {
                midletExit(); // exit
            } else if ((c == List.SELECT_COMMAND) 
                        || (c == cmdSelect)) {
                switch (mainScr.getSelectedIndex()) {
                case 0:
                    // display search screen
                    genSearchScr();
                    break;
                case 1:
                    // display name entry screen
                    genEntryScr();
                    break;
                case 2:
                    // display all names
                    genNameScr("Browse", null, null, true);
                    break;
                case 3:
                    // display option screen
                    genOptionScr();
                    break;
                default:
                    displayAlert(ERROR, "Unexpected index!",
                                 mainScr);
                }
            }
        } else if (d == nameScr) {
            // Handle a screen with names displayed, either
            // from a browse or a search
            if (c == cmdBack) {
                // display main screen
                genMainScr();
            } else if (c == cmdDial) {
                // dial the phone screen
                genDialScr();
            }
        } else if (d == entryScr) {
            // Handle the name entry screen
            if (c == cmdCancel) {
                // display main screen
                genMainScr();
            } else if (c == cmdAdd) {
                // display name entry screen
                addEntry();
            }
        } else if (d == optionScr) {
            // Handle the option screen
            if (c == cmdBack) {
                // display main screen
                genMainScr();
            }
        } else if (d == searchScr) {
            // Handle the search screen
            if (c == cmdBack) {
                // display main screen
                genMainScr();
            } else if (c == cmdSearchNetwork ||
                       c == cmdSearchLocal) {

                // display search of local addr book
                genNameScr("Search Result",
                           s_firstName.getString(),
                           s_lastName.getString(),
                           c == cmdSearchLocal);
            }
        } else if (d == dialScr) {
            if (c == cmdCancel) {
                 // display main screen
                 genMainScr();
            }
        }
    }

    /**
     * Gets called when the user is viewing the sort options
     * in the optionScr. Takes the new selected index and
     * changes the sort order (how names are displayed
     * from a search or a browse).
     *
     *  item   An item list
     */
    public void itemStateChanged(Item item) {
        if (item == sortChoice) {
            sortOrder = sortChoice.getSelectedIndex();
        }
    }
}