Android蓝牙通信聊天实现发送和接受功能

import java.util.arraylist;
import java.util.set;

import android.app.activity;
import android.app.alertdialog;
import android.bluetooth.bluetoothadapter;
import android.bluetooth.bluetoothdevice;
import android.content.broadcastreceiver;
import android.content.context;
import android.content.dialoginterface;
import android.content.intent;
import android.content.intentfilter;
import android.os.bundle;
import android.os.handler;
import android.os.message;
import android.util.log;
import android.view.menu;
import android.view.menuitem;
import android.view.view;
import android.view.view.onclicklistener;
import android.view.window;
import android.widget.button;
import android.widget.edittext;
import android.widget.textview;
import android.widget.toast;

public class bluetoothchat extends activity {

  // message types sent from the bluetoothchatservice handler
  public static final int message_state_change = 1;
  public static final int message_read = 2;
  public static final int message_write = 3;
  public static final int message_device_name = 4;
  public static final int message_toast = 5;

  // key names received from the bluetoothchatservice handler
  public static final string device_name = "device_name";
  public static final string toast = "toast";

  // intent request codes
  private static final int request_connect_device = 1;
  private static final int request_enable_bt = 2;

  private textview mtitle;
  private edittext text_chat;
  private edittext text_input;
  private button but_on_off;
  private button but_search; // ------> 在菜单中可以搜索
  private button but_create; // ------> 在菜单中设置"可被发现"
  private button msendbutton;
  // 连接到的蓝牙设备的名称
  private string mconnecteddevicename;
  // string buffer for outgoing messages
  private stringbuffer moutstringbuffer;
  // local bluetooth adapter
  private bluetoothadapter mbluetoothadapter = null;
  // member object for the chat services
  private bluetoothchatservice mchatservice = null;

  private arraylist<string> mpaireddeviceslist = new arraylist<string>();
  private arraylist<string> mnewdeviceslist = new arraylist<string>();
  private string[] strname;
  private string address;

  @override
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    requestwindowfeature(window.feature_custom_title);
    setcontentview(r.layout.main);

    mtitle = (textview) this.findviewbyid(r.id.text_title);
    text_chat = (edittext) this.findviewbyid(r.id.text_chat);
    text_input = (edittext) this.findviewbyid(r.id.text_input);
    but_on_off = (button) this.findviewbyid(r.id.but_off_on);
    but_search = (button) this.findviewbyid(r.id.but_search_div);
    but_create = (button) this.findviewbyid(r.id.but_cjlj);
    msendbutton = (button) this.findviewbyid(r.id.but_fsxx);

    // 获得本地的蓝牙适配器
    mbluetoothadapter = bluetoothadapter.getdefaultadapter();
    // 如果为null,说明没有蓝牙设备
    if (mbluetoothadapter == null) {
      toast.maketext(this, "没有蓝牙设备", toast.length_long).show();
      finish();
      return;
    }

    if (mbluetoothadapter.isenabled()) {
      but_on_off.settext("关闭蓝牙");
    } else {
      but_on_off.settext("开启蓝牙");
    }

    but_on_off.setonclicklistener(new onclicklistener() {

      @override
      public void onclick(view v) {
        if (!mbluetoothadapter.isenabled()) {
          mbluetoothadapter.enable();
          toast.maketext(bluetoothchat.this, "蓝牙已开启",
              toast.length_short).show();
          but_on_off.settext("关闭蓝牙");
        } else {
          mbluetoothadapter.disable();
          toast.maketext(bluetoothchat.this, "蓝牙已关闭",
              toast.length_short).show();
          but_on_off.settext("开启蓝牙");
        }
      }
    });

    but_search.setonclicklistener(new onclicklistener() {

      @override
      public void onclick(view v) {
        searchdevice();
      }
    });

    but_create.setonclicklistener(new onclicklistener() {

      @override
      public void onclick(view v) {

        final edittext et = new edittext(bluetoothchat.this);
        et.setsingleline();
        et.settext(mbluetoothadapter.getname());

        new alertdialog.builder(bluetoothchat.this)
            .settitle("请输入房间名：")
            .setview(et)
            .setpositivebutton("确定",
                new dialoginterface.onclicklistener() {

                  @override
                  public void onclick(dialoginterface dialog,
                      int which) {
                    string name = et.gettext().tostring()
                        .trim();
                    if (name.equals("")) {
                      toast.maketext(bluetoothchat.this,
                          "请输入房间名",
                          toast.length_short).show();
                      return;
                    }
                    // 设置房间名
                    mbluetoothadapter.setname(name);
                  }

                })
            .setnegativebutton("取消",
                new dialoginterface.onclicklistener() {

                  @override
                  public void onclick(dialoginterface dialog,
                      int which) {

                  }
                }).create().show();

        // 创建连接，也就是设备本地蓝牙设备可被其他用户的蓝牙搜到
        ensurediscoverable();
      }
    });

    // 获得一个已经配对的蓝牙设备的set集合
    set<bluetoothdevice> paireddevices = mbluetoothadapter
        .getbondeddevices();
    if (paireddevices.size() > 0) {
      for (bluetoothdevice device : paireddevices) {
        mpaireddeviceslist.add("已配对：" + device.getname() + "\n"
            + device.getaddress());
      }
    } else {
      toast.maketext(this, "没有已配对的设备", toast.length_short).show();
    }

    // 当发现一个新的蓝牙设备时注册广播
    intentfilter filter = new intentfilter(bluetoothdevice.action_found);
    this.registerreceiver(mreceiver, filter);

    // 当搜索完毕后注册广播
    filter = new intentfilter(bluetoothadapter.action_discovery_finished);
    this.registerreceiver(mreceiver, filter);

  }

  @override
  public void onstart() {
    super.onstart();
    // if bt is not on, request that it be enabled.
    // setupchat() will then be called during onactivityresult
    if (!mbluetoothadapter.isenabled()) {
      intent enableintent = new intent(
          bluetoothadapter.action_request_enable);
      startactivityforresult(enableintent, request_enable_bt);
      // otherwise, setup the chat session
    } else {
      if (mchatservice == null)
        setupchat();
    }
  }

  @override
  public synchronized void onresume() {
    super.onresume();
    // performing this check in onresume() covers the case in which bt was
    // not enabled during onstart(), so we were paused to enable it...
    // onresume() will be called when action_request_enable activity
    // returns.
    if (mchatservice != null) {
      // only if the state is state_none, do we know that we haven't
      // started already
      if (mchatservice.getstate() == bluetoothchatservice.state_none) {
        // start the bluetooth chat services
        mchatservice.start();
      }
    }
  }

  private void setupchat() {

    msendbutton.setonclicklistener(new onclicklistener() {
      public void onclick(view v) {
        // send a message using content of the edit text widget
        string message = text_input.gettext().tostring();
        sendmessage(message);
      }
    });

    // initialize the bluetoothchatservice to perform bluetooth connections
    mchatservice = new bluetoothchatservice(this, mhandler);

    // initialize the buffer for outgoing messages
    moutstringbuffer = new stringbuffer("");
  }

  @override
  public void ondestroy() {
    super.ondestroy();
    // stop the bluetooth chat services
    if (mchatservice != null)
      mchatservice.stop();

    // make sure we're not doing discovery anymore
    if (mbluetoothadapter != null) {
      mbluetoothadapter.canceldiscovery();
    }
    // unregister broadcast listeners
    this.unregisterreceiver(mreceiver);
  }

  /** 使本地的蓝牙设备可被发现 */
  private void ensurediscoverable() {
    if (mbluetoothadapter.getscanmode() != bluetoothadapter.scan_mode_connectable_discoverable) {
      intent discoverableintent = new intent(
          bluetoothadapter.action_request_discoverable);
      discoverableintent.putextra(
          bluetoothadapter.extra_discoverable_duration, 300);
      startactivity(discoverableintent);
    }
  }

  /**
   * sends a message.
   * 
   * @param message
   *      a string of text to send.
   */
  private void sendmessage(string message) {
    // check that we're actually connected before trying anything
    if (mchatservice.getstate() != bluetoothchatservice.state_connected) {
      toast.maketext(this, "没有连接上", toast.length_short).show();
      return;
    }

    // check that there's actually something to send
    if (message.length() > 0) {
      // get the message bytes and tell the bluetoothchatservice to write
      byte[] send = message.getbytes();
      mchatservice.write(send);

      // reset out string buffer to zero and clear the edit text field
      moutstringbuffer.setlength(0);
      text_input.settext(moutstringbuffer);
    }
  }

  // the handler that gets information back from the bluetoothchatservice
  private final handler mhandler = new handler() {

    @override
    public void handlemessage(message msg) {
      switch (msg.what) {
      case message_state_change:
        switch (msg.arg1) {
        case bluetoothchatservice.state_connected:
          mtitle.settext("已经连接");
          mtitle.append(mconnecteddevicename);
          // mconversationarrayadapter.clear();
          break;
        case bluetoothchatservice.state_connecting:
          mtitle.settext("正在连接中...");
          break;
        case bluetoothchatservice.state_listen:
        case bluetoothchatservice.state_none:
          mtitle.settext("未连接上");
          break;
        }
        break;
      case message_write:
        byte[] writebuf = (byte[]) msg.obj;
        // construct a string from the buffer
        string writemessage = new string(writebuf);
        // mconversationarrayadapter.add("me: " + writemessage);
        text_chat.append("我：" + writemessage + "\n");
        break;
      case message_read:
        byte[] readbuf = (byte[]) msg.obj;
        // construct a string from the valid bytes in the buffer
        string readmessage = new string(readbuf, 0, msg.arg1);
        // mconversationarrayadapter.add(mconnecteddevicename+": " +
        // readmessage);
        text_chat.append(mconnecteddevicename + "：" + readmessage
            + "\n");
        break;
      case message_device_name:
        // save the connected device's name
        mconnecteddevicename = msg.getdata().getstring(device_name);
        toast.maketext(getapplicationcontext(),
            "连接到 " + mconnecteddevicename, toast.length_short)
            .show();
        break;
      case message_toast:
        toast.maketext(getapplicationcontext(),
            msg.getdata().getstring(toast), toast.length_short)
            .show();
        break;
      }
    }
  };

  // 连接蓝牙设备
  private void linkdevice() {
    if (mbluetoothadapter.isdiscovering()) {
      mbluetoothadapter.canceldiscovery();
    }
    int cou = mpaireddeviceslist.size() + mnewdeviceslist.size();
    if (cou == 0) {
      toast.maketext(bluetoothchat.this, "没有搜索到可用的蓝牙设备",
          toast.length_short).show();
      return;
    }

    // 把已经配对的蓝牙设备和新发现的蓝牙设备的名称都放入数组中，以便在对话框列表中显示
    strname = new string[cou];
    for (int i = 0; i < mpaireddeviceslist.size(); i++) {
      strname[i] = mpaireddeviceslist.get(i);
    }
    for (int i = mpaireddeviceslist.size(); i < strname.length; i++) {
      strname[i] = mnewdeviceslist.get(i - mpaireddeviceslist.size());
    }
    address = strname[0].substring(strname[0].length() - 17);
    new alertdialog.builder(bluetoothchat.this)
        .settitle("搜索到的蓝牙设备：")
        .setsinglechoiceitems(strname, 0,
            new dialoginterface.onclicklistener() {

              @override
              public void onclick(dialoginterface dialog,
                  int which) {
                // 当用户点击选中的蓝牙设备时，取出选中的蓝牙设备的mac地址
                address = strname[which].split("\\n")[1].trim();
              }
            })
        .setpositivebutton("连接", new dialoginterface.onclicklistener() {

          @override
          public void onclick(dialoginterface dialog, int which) {
            if (address == null) {
              toast.maketext(bluetoothchat.this, "请先连接外部蓝牙设备",
                  toast.length_short).show();
              return;
            }

            log.i("sxd", "address:" + address);
            // get the bluetoothdevice object
            bluetoothdevice device = mbluetoothadapter
                .getremotedevice(address);
            // attempt to connect to the device
            mchatservice.connect(device);
          }
        })
        .setnegativebutton("取消", new dialoginterface.onclicklistener() {

          @override
          public void onclick(dialoginterface dialog, int which) {

          }
        }).create().show();
  }

  // 搜索蓝牙设备蓝牙设备
  private void searchdevice() {
    mtitle.settext("正在努力搜索中...");
    setprogressbarindeterminatevisibility(true);
    if (mbluetoothadapter.isdiscovering()) {
      mbluetoothadapter.canceldiscovery();
    }
    mnewdeviceslist.clear();
    mbluetoothadapter.startdiscovery();
  }

  @override
  public boolean oncreateoptionsmenu(menu menu) {
    menu.add(0, 1, 0, "搜索设备");
    menu.add(0, 2, 0, "可被发现");
    return true;
  }

  private final broadcastreceiver mreceiver = new broadcastreceiver() {
    @override
    public void onreceive(context context, intent intent) {
      string action = intent.getaction();
      // 当发现一个新的蓝牙设备时
      if (bluetoothdevice.action_found.equals(action)) {
        bluetoothdevice device = intent
            .getparcelableextra(bluetoothdevice.extra_device);
        // if it's already paired, skip it, because it's been listed
        // already
        if (device.getbondstate() != bluetoothdevice.bond_bonded) {
          string s = "未配对： " + device.getname() + "\n"
              + device.getaddress();
          if (!mnewdeviceslist.contains(s))
            mnewdeviceslist.add(s);
        }
        // when discovery is finished, change the activity title
      } else if (bluetoothadapter.action_discovery_finished
          .equals(action)) {
        setprogressbarindeterminatevisibility(false);
        if (mnewdeviceslist.size() == 0) {
          toast.maketext(bluetoothchat.this, "没有发现新设备",
              toast.length_short).show();
        }
        mtitle.settext("未连接");
        linkdevice();
      }
    }
  };

  @override
  public boolean onoptionsitemselected(menuitem item) {
    switch (item.getitemid()) {
    case 1:
      searchdevice();
      return true;
    case 2:
      // ensure this device is discoverable by others
      ensurediscoverable();
      return true;
    }
    return false;
  }

}

package com.it2388.bluetooth;

/*
 * copyright (c) 2009 the android open source project
 *
 * licensed under the apache license, version 2.0 (the "license");
 * you may not use this file except in compliance with the license.
 * you may obtain a copy of the license at
 *
 *   http://www.apache.org/licenses/license-2.0
 *
 * unless required by applicable law or agreed to in writing, software
 * distributed under the license is distributed on an "as is" basis,
 * without warranties or conditions of any kind, either express or implied.
 * see the license for the specific language governing permissions and
 * limitations under the license.
 */

import java.io.ioexception;
import java.io.inputstream;
import java.io.outputstream;
import java.util.uuid;

import android.bluetooth.bluetoothadapter;
import android.bluetooth.bluetoothdevice;
import android.bluetooth.bluetoothserversocket;
import android.bluetooth.bluetoothsocket;
import android.content.context;
import android.os.bundle;
import android.os.handler;
import android.os.message;
import android.util.log;

/**
 * this class does all the work for setting up and managing bluetooth
 * connections with other devices. it has a thread that listens for incoming
 * connections, a thread for connecting with a device, and a thread for
 * performing data transmissions when connected.
 * 
 * *这个类做所有的工作，建立和管理蓝牙 与其他设备的连接。它有一个线程监听 传入的连接，一个用于连接一个设备的线程，和一个 当连接时执行数据传输的线程。
 */
public class bluetoothchatservice {
  // debugging
  private static final string tag = "bluetoothchatservice";
  private static final boolean d = true;

  // name for the sdp record when creating server socket 对于sdp记录名称创建服务器套接字时
  private static final string name = "bluetoothchat";

  // unique uuid for this application
  private static final uuid my_uuid = uuid
      .fromstring("fa87c0d0-afac-11de-8a39-0800200c9a66");

  // member fields
  private final bluetoothadapter madapter;
  private final handler mhandler;
  private acceptthread macceptthread;
  private connectthread mconnectthread;
  private connectedthread mconnectedthread;
  private int mstate;

  // constants that indicate the current connection state
  public static final int state_none = 0; // we're doing nothing 我们什么都不做
  public static final int state_listen = 1; // now listening for incoming 现在监听
                        // connections
  public static final int state_connecting = 2; // now initiating an outgoing
                          // 启动一个外向
                          // connection
  public static final int state_connected = 3; // now connected to a remote
                          // 连接到一个远程
                          // device

  /**
   * constructor. prepares a new bluetoothchat session.
   * 
   * @param context
   *      the ui activity context
   * @param handler
   *      a handler to send messages back to the ui activity
   */
  public bluetoothchatservice(context context, handler handler) {
    madapter = bluetoothadapter.getdefaultadapter();
    mstate = state_none;
    mhandler = handler;
  }

  /**
   * set the current state of the chat connection
   * 
   * @param state
   *      an integer defining the current connection state
   */
  private synchronized void setstate(int state) {
    if (d)
      log.d(tag, "setstate() " + mstate + " -> " + state);
    mstate = state;

    // give the new state to the handler so the ui activity can update
    mhandler.obtainmessage(bluetoothchat.message_state_change, state, -1)
        .sendtotarget();
  }

  /**
   * return the current connection state.
   */
  public synchronized int getstate() {
    return mstate;
  }

  /**
   * start the chat service. specifically start acceptthread to begin a
   * session in listening (server) mode. called by the activity onresume()
   */
  public synchronized void start() {
    if (d)
      log.d(tag, "start");

    // cancel any thread attempting to make a connection
    if (mconnectthread != null) {
      mconnectthread.cancel();
      mconnectthread = null;
    }

    // cancel any thread currently running a connection
    if (mconnectedthread != null) {
      mconnectedthread.cancel();
      mconnectedthread = null;
    }

    // start the thread to listen on a bluetoothserversocket
    if (macceptthread == null) {
      macceptthread = new acceptthread();
      macceptthread.start();
    }
    setstate(state_listen);
  }

  /**
   * start the connectthread to initiate a connection to a remote device.
   * 
   * @param device
   *      the bluetoothdevice to connect
   */
  public synchronized void connect(bluetoothdevice device) {
    if (d)
      log.d(tag, "connect to: " + device);

    // cancel any thread attempting to make a connection
    if (mstate == state_connecting) {
      if (mconnectthread != null) {
        mconnectthread.cancel();
        mconnectthread = null;
      }
    }

    // cancel any thread currently running a connection
    if (mconnectedthread != null) {
      mconnectedthread.cancel();
      mconnectedthread = null;
    }

    // start the thread to connect with the given device
    mconnectthread = new connectthread(device);
    mconnectthread.start();
    setstate(state_connecting);
  }

  /**
   * start the connectedthread to begin managing a bluetooth connection
   * 
   * @param socket
   *      the bluetoothsocket on which the connection was made
   * @param device
   *      the bluetoothdevice that has been connected
   */
  public synchronized void connected(bluetoothsocket socket,
      bluetoothdevice device) {
    if (d)
      log.d(tag, "connected");

    // cancel the thread that completed the connection
    if (mconnectthread != null) {
      mconnectthread.cancel();
      mconnectthread = null;
    }

    // cancel any thread currently running a connection
    if (mconnectedthread != null) {
      mconnectedthread.cancel();
      mconnectedthread = null;
    }

    // cancel the accept thread because we only want to connect to one
    // device
    if (macceptthread != null) {
      macceptthread.cancel();
      macceptthread = null;
    }

    // start the thread to manage the connection and perform transmissions
    mconnectedthread = new connectedthread(socket);
    mconnectedthread.start();

    // send the name of the connected device back to the ui activity
    message msg = mhandler.obtainmessage(bluetoothchat.message_device_name);
    bundle bundle = new bundle();
    bundle.putstring(bluetoothchat.device_name, device.getname());
    msg.setdata(bundle);
    mhandler.sendmessage(msg);

    setstate(state_connected);
  }

  /**
   * stop all threads
   */
  public synchronized void stop() {
    if (d)
      log.d(tag, "stop");
    if (mconnectthread != null) {
      mconnectthread.cancel();
      mconnectthread = null;
    }
    if (mconnectedthread != null) {
      mconnectedthread.cancel();
      mconnectedthread = null;
    }
    if (macceptthread != null) {
      macceptthread.cancel();
      macceptthread = null;
    }
    setstate(state_none);
  }

  /**
   * write to the connectedthread in an unsynchronized manner
   * 
   * @param out
   *      the bytes to write
   * @see connectedthread#write(byte[])
   */
  public void write(byte[] out) {
    // create temporary object
    connectedthread r;
    // synchronize a copy of the connectedthread
    synchronized (this) {
      if (mstate != state_connected)
        return;
      r = mconnectedthread;
    }
    // perform the write unsynchronized
    r.write(out);
  }

  /**
   * indicate that the connection attempt failed and notify the ui activity.
   */
  private void connectionfailed() {
    setstate(state_listen);

    // send a failure message back to the activity
    message msg = mhandler.obtainmessage(bluetoothchat.message_toast);
    bundle bundle = new bundle();
    bundle.putstring(bluetoothchat.toast, "不能连接到设备");
    msg.setdata(bundle);
    mhandler.sendmessage(msg);
  }

  /**
   * indicate that the connection was lost and notify the ui activity.
   */
  private void connectionlost() {
    setstate(state_listen);

    // send a failure message back to the activity
    message msg = mhandler.obtainmessage(bluetoothchat.message_toast);
    bundle bundle = new bundle();
    bundle.putstring(bluetoothchat.toast, "设备连接中断");
    msg.setdata(bundle);
    mhandler.sendmessage(msg);
  }

  /**
   * this thread runs while listening for incoming connections. it behaves
   * like a server-side client. it runs until a connection is accepted (or
   * until cancelled).
   */
  private class acceptthread extends thread {
    // the local server socket
    private final bluetoothserversocket mmserversocket;

    public acceptthread() {
      bluetoothserversocket tmp = null;
      // create a new listening server socket
      try {
        tmp = madapter
            .listenusingrfcommwithservicerecord(name, my_uuid);
      } catch (ioexception e) {
        log.e("sxd", " ======== ufcomm exception =======", e);
      }
      mmserversocket = tmp;
    }

    public void run() {
      if (d)
        log.d(tag, "begin macceptthread" + this);
      setname("acceptthread");
      bluetoothsocket socket = null;

      // listen to the server socket if we're not connected
      while (mstate != state_connected) {
        try {
          // this is a blocking call and will only return on a
          // successful connection or an exception
          socket = mmserversocket.accept();
        } catch (ioexception e) {
          log.e("sxd", "---> accept socket failed <---", e);
          break;
        }

        // if a connection was accepted
        if (socket != null) {
          synchronized (bluetoothchatservice.this) {
            switch (mstate) {
            case state_listen:
            case state_connecting:
              // situation normal. start the connected thread.
              connected(socket, socket.getremotedevice());
              break;
            case state_none:
            case state_connected:
              // either not ready or already connected. terminate
              // new socket.
              try {
                socket.close();
              } catch (ioexception e) {
                log.e(tag, "could not close unwanted socket", e);
              }
              break;
            }
          }
        }
      }
      if (d)
        log.i(tag, "end macceptthread");
    }

    public void cancel() {
      if (d)
        log.d(tag, "cancel " + this);
      try {
        mmserversocket.close();
      } catch (ioexception e) {
        log.e(tag, "close() of server failed", e);
      }
    }
  }

  /**
   * this thread runs while attempting to make an outgoing connection with a
   * device. it runs straight through; the connection either succeeds or
   * fails.
   */
  private class connectthread extends thread {
    private final bluetoothsocket mmsocket;
    private final bluetoothdevice mmdevice;

    public connectthread(bluetoothdevice device) {
      mmdevice = device;
      bluetoothsocket tmp = null;

      // get a bluetoothsocket for a connection with the
      // given bluetoothdevice
      try {
        tmp = device.createrfcommsockettoservicerecord(my_uuid);
      } catch (ioexception e) {
        log.e(tag, "create() failed", e);
      }
      mmsocket = tmp;
    }

    public void run() {
      log.i(tag, "begin mconnectthread");
      setname("connectthread");

      // always cancel discovery because it will slow down a connection
      madapter.canceldiscovery();

      // make a connection to the bluetoothsocket
      try {
        // this is a blocking call and will only return on a
        // successful connection or an exception
        mmsocket.connect();
      } catch (ioexception e) {
        log.e("sxd", "链接发生了异常", e);
        connectionfailed();
        // close the socket
        try {
          mmsocket.close();
        } catch (ioexception e2) {
          log.e(tag,
              "unable to close() socket during connection failure",
              e2);
        }
        // start the service over to restart listening mode
        bluetoothchatservice.this.start();
        return;
      }

      // reset the connectthread because we're done
      synchronized (bluetoothchatservice.this) {
        mconnectthread = null;
      }

      // start the connected thread
      connected(mmsocket, mmdevice);
    }

    public void cancel() {
      try {
        mmsocket.close();
      } catch (ioexception e) {
        log.e(tag, "close() of connect socket failed", e);
      }
    }
  }

  /**
   * this thread runs during a connection with a remote device. it handles all
   * incoming and outgoing transmissions.
   * 
   * 和已经建立连接的设置进行数据的传输
   */
  private class connectedthread extends thread {
    private final bluetoothsocket mmsocket;
    private final inputstream mminstream;
    private final outputstream mmoutstream;

    public connectedthread(bluetoothsocket socket) {
      log.d(tag, "create connectedthread");
      mmsocket = socket;
      inputstream tmpin = null;
      outputstream tmpout = null;

      // get the bluetoothsocket input and output streams
      try {
        tmpin = socket.getinputstream();
        tmpout = socket.getoutputstream();
      } catch (ioexception e) {
        log.e(tag, "temp sockets not created", e);
      }

      mminstream = tmpin;
      mmoutstream = tmpout;
    }

    public void run() {
      log.i(tag, "begin mconnectedthread");
      byte[] buffer = new byte[1024];
      int bytes;

      // keep listening to the inputstream while connected
      while (true) {
        try {
          // read from the inputstream
          bytes = mminstream.read(buffer);

          // send the obtained bytes to the ui activity
          mhandler.obtainmessage(bluetoothchat.message_read, bytes,
              -1, buffer).sendtotarget();
        } catch (ioexception e) {
          log.e(tag, "disconnected", e);
          connectionlost();
          break;
        }
      }
    }

    /**
     * write to the connected outstream.
     * 
     * @param buffer
     *      the bytes to write
     */
    public void write(byte[] buffer) {
      try {
        mmoutstream.write(buffer);

        // share the sent message back to the ui activity
        mhandler.obtainmessage(bluetoothchat.message_write, -1, -1,
            buffer).sendtotarget();
      } catch (ioexception e) {
        log.e(tag, "exception during write", e);
      }
    }

    public void cancel() {
      try {
        mmsocket.close();
      } catch (ioexception e) {
        log.e(tag, "close() of connect socket failed", e);
      }
    }
  }
}