btimageclient.java

一个利用手机上的bluetooth来开发的小程序 也是很经典的例子

/*
 * @(#)BTImageClient.java	1.1 04/04/24
 *
 * Copyright (c) 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms
 */
package example.bluetooth.demo;

// jsr082 API
import javax.bluetooth.BluetoothStateException;
import javax.bluetooth.DataElement;
import javax.bluetooth.DeviceClass;
import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.DiscoveryListener;
import javax.bluetooth.LocalDevice;
import javax.bluetooth.RemoteDevice;
import javax.bluetooth.ServiceRecord;
import javax.bluetooth.UUID;

// midp/cldc API
import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.microedition.lcdui.Image;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

/**
 * Initialize BT device, search for BT services,
 * presents them to user and picks his/her choice,
 * finally download the choosen image and present
 * it to user.
 *
 * @author Vladimir K. Beliaev
 * @version 1.1, 04/24/04
 */
final class BTImageClient implements Runnable, DiscoveryListener {

    /** Describes this server - note, it's a "short" UUID. */
    private static final UUID PICTURES_SERVER_UUID = new UUID(0x12345);

    /** The attribute id of the record item with images names. */
    private static final int IMAGES_NAMES_ATTRIBUTE_ID = 0x4321;

    /** Shows the engine is ready to work. */
    private static final int READY = 0;

    /** Shows the engine is searching bluetooth devices. */
    private static final int DEVICE_SEARCH = 1;

    /** Shows the engine is searching bluetooth services. */
    private static final int SERVICE_SEARCH = 2;

    /** Keeps the current state of engine. */
    private int state = READY;

    /** Keeps the discovery agent reference. */
    private DiscoveryAgent discoveryAgent;

    /** Keeps the parent reference to process specific actions. */
    private GUIImageClient parent;

    /** Becomes 'true' when this component is finilized. */
    private boolean isClosed;

    /** Proccess the search/download requests. */
    private Thread processorThread;

    /** Collects the remote devices found during a search. */
    private Vector /* RemoteDevice */ devices = new Vector();

    /** Collects the services found during a search. */
    private Vector /* ServiceRecord */ records = new Vector();

    /** Keeps the device discovery return code. */
    private int discType;

    /** Keeps the services search IDs (just to be able to cancel them). */
    private int[] searchIDs;

    /** Keeps the image name to be load. */
    private String imageNameToLoad;

    /** Keeps the table of {name, Service} to process the user choice. */
    private Hashtable base = new Hashtable();

    /** Informs the thread the download should be canceled. */
    private boolean isDownloadCanceled;

    /** Optimization: keeps service search patern. */
    private UUID[] uuidSet;

    /** Optimization: keeps attributes list to be retrieved. */
    private int[] attrSet;

    /**
     * Constructs the bluetooth server, but it is initialized
     * in the different thread to "avoid dead lock".
     */
    BTImageClient(GUIImageClient parent) {
        this.parent = parent;

        // we have to initialize a system in different thread...
        processorThread = new Thread(this);
        processorThread.start();
    }

    /**
     * Process the search/download requests.
     */
    public void run() {

        // initialize bluetooth first
        boolean isBTReady = false;

        try {

            // create/get a local device and discovery agent
            LocalDevice localDevice = LocalDevice.getLocalDevice();
            discoveryAgent = localDevice.getDiscoveryAgent();

            // remember we've reached this point.
            isBTReady = true;
        } catch (Exception e) {
            System.err.println("Can't initialize bluetooth: " + e);
        }
        parent.completeInitialization(isBTReady);

        // nothing to do if no bluetooth available
        if (!isBTReady) {
            return;
        }

        // initialize some optimization variables
        uuidSet = new UUID[2];

        // ok, we are interesting in btspp services only
        uuidSet[0] = new UUID(0x1101);

        // and only known ones, that alllows pictures
        uuidSet[1] = PICTURES_SERVER_UUID;

        // we need an only service attribute actually
        attrSet = new int[1];

        // it's "images names" one
        attrSet[0] = IMAGES_NAMES_ATTRIBUTE_ID;

        // start processing the images search/download
        processImagesSearchDownload();
    }

    /**
     * Invoked by system when a new remote device is found -
     * remember the found device.
     */
    public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {

        // same device may found several times during single search
        if (devices.indexOf(btDevice) == -1) {
            devices.addElement(btDevice);
        }
    }

    /**
     * Invoked by system when device discovery is done.
     * <p>
     * Use a trick here - just remember the discType
     * and process its evaluation in another thread.
     */
    public void inquiryCompleted(int discType) {
        this.discType = discType;

        synchronized (this) {
            notify();
        }
    }

    public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
        for (int i = 0; i < servRecord.length; i++) {
            records.addElement(servRecord[i]);
        }
    }

    public void serviceSearchCompleted(int transID, int respCode) {

        // first, find the service search transaction index
        int index = -1;

        for (int i = 0; i < searchIDs.length; i++) {
            if (searchIDs[i] == transID) {
                index = i;
                break;
            }
        }

        // error - unexpected transaction index
        if (index == -1) {
            System.err.println("Unexpected transaction index: " + transID);

            // FIXME: process the error case
        } else {
            searchIDs[index] = -1;
        }

        /*
         * Actually, we do not care about the response code -
         * if device is not reachable or no records, etc.
         */

        // make sure it was the last transaction
        for (int i = 0; i < searchIDs.length; i++) {
            if (searchIDs[i] != -1) {
                return;
            }
        }

        // ok, all of the transactions are completed
        synchronized (this) {
            notify();
        }
    }

    /** Sets the request to search the devices/services. */
    void requestSearch() {
        synchronized (this) {
            notify();
        }
    }

    /** Cancel's the devices/services search. */
    void cancelSearch() {
        synchronized (this) {
            if (state == DEVICE_SEARCH) {
                discoveryAgent.cancelInquiry(this);
            } else if (state == SERVICE_SEARCH) {
                for (int i = 0; i < searchIDs.length; i++) {
                    discoveryAgent.cancelServiceSearch(searchIDs[i]);
                }
            }
        }
    }

    /** Sets the request to search the devices/services. */
    void requestLoad(String name) {
        synchronized (this) {
            imageNameToLoad = name;
            notify();
        }
    }

    /** Cancel's the image downlaod. */
    void cancelLoad() {

        /*
         * The image download process is done by
         * this class's thread (not by a system one),
         * so no need to wake up the current thread -
         * it's running already.
         */
        isDownloadCanceled = true;
    }

    /**
     * Destroy a work with bluetooth - exits the accepting
     * thread and close notifier.
     */
    void destroy() {
        synchronized (this) {
            isClosed = true;
            isDownloadCanceled = true;
            notify();

            // FIXME: implement me
        }

        // wait for acceptor thread is done
        try {
            processorThread.join();
        } catch (InterruptedException e) {} // ignore
    }

    /**
     * Processes images seach/download until component is closed
     * or system error has happen.
     */
    private synchronized void processImagesSearchDownload() {
        while (!isClosed) {

            // wait for new search request from user
            state = READY;

            try {
                wait();
            } catch (InterruptedException e) {
                System.err.println("Unexpected interuption: " + e);
                return;
            }

            // check the component is destroyed
            if (isClosed) {
                return;
            }

            // search for devices
            if (!searchDevices()) {
                return;
            } else if (devices.size() == 0) {
                continue;
            }

            // search for services now
            if (!searchServices()) {
                return;
            } else if (records.size() == 0) {
                continue;
            }

            // ok, something was found - present the result to user now
            if (!presentUserSearchResults()) {

                // services are found, but no names there
                continue;
            }

            // the several download requests may be processed
            while (true) {

                // this download is not canceled, right?