目前，很多手機已經具備了藍牙功能。雖然MIDP2.0沒有包括藍牙API,但是JCP定義了JSR82, Java APIs for Bluetooth Wireless Technology (JABWT).這是一個可選API,很多支持MIDP2.0的手機已經實現了，比如Nokia 6600, Nokia 6670，Nokia7610等等。對于一個開發者來說,如果目標平臺支持JSR82的話，在制作聯網對戰類型游戲或者應用的時候，藍牙是一個相當不錯的選擇。本文給出了一個簡單的藍牙應用的J2ME程序，用以幫助開發者快速的掌握JSR82。該程序分別在2臺藍牙設備上安裝后，一臺設備作為服務端先運行，一臺設備作為客戶端后運行。在服務端上我們發布了一個服務，該服務的功能是把客戶端發過來的字符串轉變為大寫字符串。客戶端起動并搜索到服務端的服務后，我們就可以從客戶端的輸入框里輸入任意的字符串，發送到服務端去，同時觀察服務端的反饋結果。

　　本文并不具體講述藍牙的運行機制和JSR82的API結構，關于這些知識點，請參考本文的參考資料一節，這些參考資料會給你一個權威的精確的解釋

　　實例代碼

　　該程序包括3個java文件。一個是MIDlet,另外2個為服務端GUI和客戶端GUI。該程序已經在wtk22模擬器和Nokia 6600,Nokia 6670兩款手機上測試通過。

StupidBTMIDlet.java

import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.List;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

/**
* @author Jagie
*
* MIDlet
*/
public class StupidBTMIDlet extends MIDlet implements CommandListener {
List list;

ServerBox sb;

ClientBox cb;

/*
* (non-Javadoc)
*
* @see javax.microedition.midlet.MIDlet#startApp()
*/
protected void startApp() throws MIDletStateChangeException {
list = new List("傻瓜藍牙入門", List.IMPLICIT);
list.append("Client", null);
list.append("Server", null);
list.setCommandListener(this);
Display.getDisplay(this).setCurrent(list);

}

/**
* debug方法
* @param s 要顯示的字串
*/

public void showString(String s) {
Displayable dp = Display.getDisplay(this).getCurrent();
Alert al = new Alert(null, s, null, AlertType.INFO);
al.setTimeout(2000);
Display.getDisplay(this).setCurrent(al, dp);
}

/**
* 顯示主菜單
*
*/

public void showMainMenu() {
Display.getDisplay(this).setCurrent(list);
}


protected void pauseApp() {
// TODO Auto-generated method stub

}

public void commandAction(Command com, Displayable disp) {
if (com == List.SELECT_COMMAND) {
List list = (List) disp;
int index = list.getSelectedIndex();
if (index == 1) {
if (sb == null) {
sb = new ServerBox(this);
}
sb.setString(null);
Display.getDisplay(this).setCurrent(sb);
} else {
//每次都生成新的客戶端實例
cb = null;
System.gc();
cb = new ClientBox(this);

Display.getDisplay(this).setCurrent(cb);
}
}
}


protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
// TODO Auto-generated method stub

}

}


ClientBox.java

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import java.util.Vector;

import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.form;
import javax.microedition.lcdui.Gauge;
import javax.microedition.lcdui.StringItem;
import javax.microedition.lcdui.TextField;

//jsr082 API
import javax.bluetooth.BluetoothStateException;

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;

/**
* 客戶端GUI
* @author Jagie
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code style - Code Templates
*/
public class ClientBox extends form implements Runnable, CommandListener,
DiscoveryListener {


//字串輸入框
TextField input = new TextField(null, "", 50, TextField.ANY);
//loger
StringItem result = new StringItem("結果:", "");

private DiscoveryAgent discoveryAgent;


private UUID[] uuidSet;

//響應服務的UUID
private static final UUID ECHO_SERVER_UUID = new UUID(
"F0E0D0C0B0A000908070605040302010", false);

//設備集合
Vector devices = new Vector();
//服務集合
Vector records = new Vector();

//服務搜索的事務id集合
int[] transIDs;
StupidBTMIDlet midlet;

public ClientBox(StupidBTMIDlet midlet) {
super("");
this.midlet=midlet;

this.append(result);

this.addCommand(new Command("取消",Command.CANCEL,1));
this.setCommandListener(this);

new Thread(this).start();
}

public void commandAction(Command arg0, Displayable arg1) {
if(arg0.getCommandType()==Command.CANCEL){
midlet.showMainMenu();
}else{
//匿名內部Thread，訪問遠程服務。
Thread fetchThread=new Thread(){
public void run(){
for(int i=0;i<records.size();i++){
ServiceRecord sr=(ServiceRecord)records.elementAt(i);
if(accessService(sr)){
//訪問到一個可用的服務即可
break;
}
}
}
};
fetchThread.start();
}

}


private boolean accessService(ServiceRecord sr){
boolean result=false;
try {
String url = sr.getConnectionURL(
ServiceRecord.NOAUTHENTICATE_NOENCRYPT, false);
StreamConnection conn = (StreamConnection) Connector.open(url);

DataOutputStream dos=conn.openDataOutputStream();
dos.writeUTF(input.getString());
dos.close();
DataInputStream dis=conn.openDataInputStream();
String echo=dis.readUTF();
dis.close();
showInfo("反饋結果是:"+echo);
result=true;

} catch (IOException e) {

}
return result;
}

public synchronized void run() {
//發現設備和服務的過程中，給用戶以Gauge
Gauge g=new Gauge(null,false,Gauge.INDEFINITE,Gauge.CONTINUOUS_RUNNING);
this.append(g);
showInfo("藍牙初始化...");
boolean isBTReady = false;

try {

LocalDevice localDevice = LocalDevice.getLocalDevice();
discoveryAgent = localDevice.getDiscoveryAgent();

isBTReady = true;
} catch (Exception e) {
e.printStackTrace();
}

if (!isBTReady) {
showInfo("藍牙不可用");
//刪除Gauge
this.delete(1);
return;
}

uuidSet = new UUID[2];

//標志我們的響應服務的UUID集合
uuidSet[0] = new UUID(0x1101);
uuidSet[1] = ECHO_SERVER_UUID;

try {
discoveryAgent.startInquiry(DiscoveryAgent.GIAC, this);
} catch (BluetoothStateException e) {

}

try {
//阻塞,由inquiryCompleted()回調方法喚醒
wait();
} catch (InterruptedException e1) {

e1.printStackTrace();
}
showInfo("設備搜索完畢,共找到"+devices.size()+"個設備,開始搜索服務");
transIDs = new int[devices.size()];
for (int i = 0; i < devices.size(); i++) {
RemoteDevice rd = (RemoteDevice) devices.elementAt(i);
try {
//記錄每一次服務搜索的事務id
transIDs[i] = discoveryAgent.searchServices(null, uuidSet,
rd, this);
} catch (BluetoothStateException e) {
continue;
}

}

try {
//阻塞,由serviceSearchCompleted()回調方法在所有設備都搜索完的情況下喚醒
wait();
} catch (InterruptedException e1) {
e1.printStackTrace();
}

showInfo("服務搜索完畢,共找到"+records.size()+"個服務,準備發送請求");
if(records.size()>0){
this.append(input);
this.addCommand(new Command("發送",Command.OK,0));
}

//刪除Gauge
this.delete(1);

}

/**
* debug
* @param s
*/

private void showInfo(String s){
StringBuffer sb=new StringBuffer(result.getText());
if(sb.length()>0){
sb.append("\n");
}
sb.append(s);
result.setText(sb.toString());

}

/**
* 回調方法
*/

public void deviceDiscovered(RemoteDevice btDevice, DeviceClass cod) {

if (devices.indexOf(btDevice) == -1) {
devices.addElement(btDevice);
}
}

/**
* 回調方法，喚醒初始化線程
*/
public void inquiryCompleted(int discType) {

synchronized (this) {
notify();
}
}
/**
* 回調方法
*/
public void servicesDiscovered(int transID, ServiceRecord[] servRecord) {
for (int i = 0; i < servRecord.length; i++) {
records.addElement(servRecord[i]);
}
}

/**
* 回調方法，喚醒初始化線程
*/

public void serviceSearchCompleted(int transID, int respCode) {

for (int i = 0; i < transIDs.length; i++) {
if (transIDs[i] == transID) {
transIDs[i] = -1;
break;
}
}

//如果所有的設備都已經搜索服務完畢，則喚醒初始化線程。

boolean finished = true;
for (int i = 0; i < transIDs.length; i++) {
if (transIDs[i] != -1) {
finished = false;
break;
}
}

if (finished) {
synchronized (this) {
notify();
}
}

}

}

ServerBox.java

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;

import java.util.Vector;

import javax.bluetooth.DiscoveryAgent;
import javax.bluetooth.LocalDevice;
import javax.bluetooth.ServiceRecord;
import javax.bluetooth.UUID;
import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.microedition.io.StreamConnectionNotifier;

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Displayable;

import javax.microedition.lcdui.TextBox;
import javax.microedition.lcdui.TextField;

/**
* 服務端GUI
* @author Jagie
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code style - Code Templates
*/
public class ServerBox extends TextBox implements Runnable, CommandListener {

Command com_pub = new Command("開啟服務", Command.OK, 0);

Command com_cancel = new Command("終止服務", Command.CANCEL, 0);

Command com_back = new Command("返回", Command.BACK, 1);

LocalDevice localDevice;

StreamConnectionNotifier notifier;

ServiceRecord record;

boolean isClosed;

ClientProcessor processor;

StupidBTMIDlet midlet;
//響應服務的uuid
private static final UUID ECHO_SERVER_UUID = new UUID(
"F0E0D0C0B0A000908070605040302010", false);

public ServerBox(StupidBTMIDlet midlet) {
super(null, "", 500, TextField.ANY);
this.midlet = midlet;
this.addCommand(com_pub);
this.addCommand(com_back);
this.setCommandListener(this);
}


public void run() {
boolean isBTReady = false;

try {

localDevice = LocalDevice.getLocalDevice();

if (!localDevice.setDiscoverable(DiscoveryAgent.GIAC)) {
showInfo("無法設置設備發現模式");
return;
}

// prepare a URL to create a notifier
StringBuffer url = new StringBuffer("btspp://");

// indicate this is a server
url.append("localhost").append(':');

// add the UUID to identify this service
url.append(ECHO_SERVER_UUID.toString());

// add the name for our service
url.append(";name=Echo Server");

// request all of the client not to be authorized
// some devices fail on authorize=true
url.append(";authorize=false");

// create notifier now
notifier = (StreamConnectionNotifier) Connector
.open(url.toString());

record = localDevice.getRecord(notifier);

// remember we've reached this point.
isBTReady = true;
} catch (Exception e) {
e.printStackTrace();

}

// nothing to do if no bluetooth available
if (isBTReady) {
showInfo("初始化成功，等待連接");
this.removeCommand(com_pub);
this.addCommand(com_cancel);
} else {
showInfo("初始化失敗,退出");
return;

}

// 生成服務端服務線程對象
processor = new ClientProcessor();

// ok, start accepting connections then
while (!isClosed) {
StreamConnection conn = null;

try {
conn = notifier.acceptAndOpen();
} catch (IOException e) {
// wrong client or interrupted - continue anyway
continue;
}
processor.addConnection(conn);
}

}

public void publish() {
isClosed = false;
this.setString(null);
new Thread(this).start();

}

public void cancelService() {
isClosed = true;
showInfo("服務終止");
this.removeCommand(com_cancel);
this.addCommand(com_pub);
}

/*
* (non-Javadoc)
*
* @see javax.microedition.lcdui.CommandListener#commandAction(javax.microedition.lcdui.Command,
* javax.microedition.lcdui.Displayable)
*/
public void commandAction(Command arg0, Displayable arg1) {
if (arg0 == com_pub) {
//發布service
publish();
} else if (arg0 == com_cancel) {
cancelService();
} else {
cancelService();
midlet.showMainMenu();
}

}

/**
* 內部類，服務端服務線程。
* @author Jagie
*
* TODO To change the template for this generated type comment go to
* Window - Preferences - Java - Code style - Code Templates
*/
private class ClientProcessor implements Runnable {
private Thread processorThread;

private Vector queue = new Vector();

private boolean isOk = true;

ClientProcessor() {
processorThread = new Thread(this);
processorThread.start();
}

public void run() {
while (!isClosed) {

synchronized (this) {
if (queue.size() == 0) {
try {
//阻塞，直到有新客戶連接
wait();
} catch (InterruptedException e) {

}
}
}

//處理連接隊列

StreamConnection conn;

synchronized (this) {

if (isClosed) {
return;
}
conn = (StreamConnection) queue.firstElement();
queue.removeElementAt(0);
processConnection(conn);
}
}
}

/**
* 往連接隊列添加新連接，同時喚醒處理線程
* @param conn
*/

void addConnection(StreamConnection conn) {
synchronized (this) {
queue.addElement(conn);
notify();
}
}

}

/**
* 從StreamConnection讀取輸入
* @param conn
* @return
*/
private String readInputString(StreamConnection conn) {
String inputString = null;

try {

DataInputStream dis = conn.openDataInputStream();
inputString = dis.readUTF();
dis.close();
} catch (Exception e) {
e.printStackTrace();
}
return inputString;
}

/**
* debug
* @param s
*/

private void showInfo(String s) {
StringBuffer sb = new StringBuffer(this.getString());
if (sb.length() > 0) {
sb.append("\n");
}

sb.append(s);
this.setString(sb.toString());

}


/**
* 處理客戶端連接
* @param conn
*/
private void processConnection(StreamConnection conn) {

// 讀取輸入
String inputString = readInputString(conn);
//生成響應
String outputString = inputString.toUpperCase();
//輸出響應
sendOutputData(outputString, conn);

try {
conn.close();
} catch (IOException e) {
} // ignore
showInfo("客戶端輸入:" + inputString + ",已成功響應!");
}

/**
* 輸出響應
* @param outputData
* @param conn
*/

private void sendOutputData(String outputData, StreamConnection conn) {

try {
DataOutputStream dos = conn.openDataOutputStream();
dos.writeUTF(outputData);
dos.close();
} catch (IOException e) {
}

}
}
　　小結

　　本文給出了一個簡單的藍牙服務的例子。旨在幫助開發者快速掌握JSR82.如果該文能對你有所啟發,那就很好了。