§ 概述

目前，很多手机已经具备了蓝牙功能。虽然MIDP2.0没有包括蓝牙API,但是JCP定义了JSR82, Java APIs for Bluetooth Wireless Technology (JABWT).这是一个可选API,很多支持MIDP2.0的手机已经实现了，比如Nokia 6600, Nokia 6670，Nokia7610等等。对于一个开发者来说,如果目标平台支持JSR82的话，在制作联网对战类型游戏或者应用的时候，蓝牙是一个相当不错的选择。本文给出了一个最简单的蓝牙应用的J2ME程序，用以帮助开发者快速的掌握JSR82。该程序分别在2台蓝牙设备上安装后，一台设备作为服务端先运行，一台设备作为客户端后运行。在服务端上我们发布了一个服务，该服务的功能是把客户端发过来的字符串转变为大写字符串。客户端起动并搜索到服务端的服务后，我们就可以从客户端的输入框里输入任意的字符串，发送到服务端去，同时观察服务端的反馈结果。

本文并不具体讲述蓝牙的运行机制和JSR82的API结构，关于这些知识点，请参考本文的参考资料一节，这些参考资料会给你一个权威的精确的解释。

§ 实例代码

该程序包括3个java文件。一个是MIDlet,另外2个为服务端GUI和客户端GUI。该程序已经在wtk22模拟器和Nokia 6600,Nokia 6670两款手机上测试通过。

StupidBTMIDlet.java

import javax.microedition.lcdui.Aler

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.Lis

import javax.microedition.midlet.MIDle

import javax.microedition.midlet.MIDletStateChangeException;

/**

* @author Jagie

*

*　MIDlet

*/

public class StupidBTMIDlet extends MIDlet implements CommandListener {

List lis

ServerBox sb;

ClientBox cb;

/*

* (non-Javadoc)

*

* @see javax.microedition.midlet.MIDlet#startApp()

*/

protected void startApp() throws MIDletStateChangeException {

list = new List("傻瓜蓝牙入门", List.IMPLICIT);

list.append("Client", null);

list.append("Server", null);

list.setCommandListener(this);

Display.getDisplay(this).setCurrent(list);

}

/**

* debug方法

* @param s 要显示的字串

*/

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);

}

/**

* 显示主菜单

*

*/

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 {

//每次都生成新的客户端实例

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.DiscoveryAgen

import javax.bluetooth.DiscoveryListener;

import javax.bluetooth.LocalDevice;

import javax.bluetooth.RemoteDevice;

import javax.bluetooth.ServiceRecord;

import javax.bluetooth.UUID;

/**

* 客户端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 {

//字串输入框

TextField input = new TextField(null, "", 50, TextField.ANY);

//loger

StringItem result = new StringItem("结果:", "");

private DiscoveryAgent discoveryAgen

private UUID【】 uuidSe

//响应服务的UUID

private static final UUID ECHO_SERVER_UUID = new UUID(

"F0E0D0C0B0A000908070605040302010", false);

//设备集合

Vector devices = new Vector();

//服务集合

Vector records = new Vector();

//服务搜索的事务id集合

int【】 transIDs;

StupidBTMIDlet midle

public ClientBox(StupidBTMIDlet midlet) {

super("");

this.midlet=midle

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{

//匿名内部Thread，访问远程服务。

Thread fetchThread=new Thread(){

public void run(){

for(int i=0;irecords.size();i++){

ServiceRecord sr=(ServiceRecord)records.elementAt(i);

if(accessService(sr)){

//访问到一个可用的服务即可

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("反馈结果是:"+echo);

result=true;

} catch (IOException e) {

}

return resul

}

public synchronized void run() {

//发现设备和服务的过程中，给用户以Gauge

Gauge g=new Gauge(null,false,Gauge.INDEFINITE,Gauge.CONTINUOUS_RUNNING);

this.append(g);

showInfo("蓝牙初始化...");

boolean isBTReady = false;

try {

LocalDevice localDevice = LocalDevice.getLocalDevice();

discoveryAgent = localDevice.getDiscoveryAgent();

isBTReady = true;

} catch (Exception e) {

e.printStackTrace();

}

if (!isBTReady) {

showInfo("蓝牙不可用");

//删除Gauge

this.delete(1);

return;

}

uuidSet = new UUID;

//标志我们的响应服务的UUID集合

uuidSet【0】 = new UUID(0x1101);

uuidSet = ECHO_SERVER_UUID;

try {

discoveryAgent.startInquiry(DiscoveryAgent.GIAC, this);

} catch (BluetoothStateException e) {

}

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