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J2ME蓝牙手机应用程序开发实战入门


  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。
  
  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.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
  ("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.DiscoveryAgent;
  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 discoveryAgent;
  
  private UUID[] uuidSet;
  
  //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 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{
  //匿名内部Thread,访问远程服务。
  Thread fetchThread=new Thread()
  {
  public void run()
  {
  for(int i=0;i<records.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 result;
  }
  
  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[2];
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