一.安卓蓝牙开发基本流程
- 获取本地蓝牙适配器，打开蓝牙，获得已配对蓝牙设备列表
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
mBtAdapter.enable();
Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();
- 扫描未配对设备，通过广播（BluetoothDevice.ACTION_FOUND）接收列表出未配对的设备
mBtAdapter.startDiscovery();
- 从列表设备选择某个蓝牙进行连接，获得BluetoothDevice 对象
device.getName()
device.getAddress()
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address)
- 开始连接线程，获得BluetoothSocket
private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
BluetoothSocket bluetoothSocket= device.createRfcommSocketToServiceRecord(MY_UUID)
- 开始已连接线程，由BluetoothSocket获得输入输出流从而收发数据
二.权限申明
1 <!--蓝牙权限--> 2 <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" /> 3 <uses-permission android:name="android.permission.BLUETOOTH" />
三.布局文件
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 xmlns:tools="http://schemas.android.com/tools" 4 android:id="@+id/activity_main" 5 android:layout_width="match_parent" 6 android:layout_height="match_parent" 7 android:orientation="vertical" 8 > 9 <!--标题栏--> 10 <LinearLayout 11 android:layout_width="match_parent" 12 android:layout_height="wrap_content" 13 android:background="#CDC9C9"> 14 <TextView 15 android:id="@+id/DeviceTextView" 16 android:layout_width="wrap_content" 17 android:layout_weight="1" 18 android:layout_height="wrap_content" 19 android:text="设备：" 20 android:textColor="#FFFFFF" 21 android:textSize="20dp" 22 /> 23 <TextView 24 android:id="@+id/StateTextView" 25 android:layout_width="wrap_content" 26 android:layout_weight="1" 27 android:layout_height="wrap_content" 28 android:text="状态：" 29 android:textColor="#FFFFFF" 30 android:textSize="20dp" 31 /> 32 </LinearLayout> 33 <!--聊天界面--> 34 <LinearLayout 35 android:id="@+id/chatPage" 36 android:layout_width="match_parent" 37 android:layout_height="wrap_content" 38 android:orientation="vertical" 39 android:visibility="gone" 40 android:layout_marginLeft="10dp" 41 android:layout_marginRight="10dp" 42 > 43 <LinearLayout 44 android:layout_width="match_parent" 45 android:layout_height="wrap_content" 46 47 > 48 <EditText 49 android:id="@+id/MessageEditText" 50 android:layout_marginTop="5dp" 51 android:layout_width="wrap_content" 52 android:layout_weight="1" 53 android:layout_height="40dp" 54 /> 55 <Button 56 android:id="@+id/SendButton" 57 android:layout_width="wrap_content" 58 android:layout_height="wrap_content" 59 android:layout_marginTop="4dp" 60 android:textAllCaps="false" 61 android:text="Send" 62 /> 63 </LinearLayout> 64 <LinearLayout 65 android:layout_width="match_parent" 66 android:layout_height="wrap_content"> 67 <TextView 68 android:id="@+id/DisplayTextView" 69 android:layout_width="match_parent" 70 android:layout_height="wrap_content" 71 android:hint="DisplayTextView"/> 72 </LinearLayout> 73 74 </LinearLayout> 75 <!--控制界面--> 76 <LinearLayout 77 android:id="@+id/controlPage" 78 android:layout_width="match_parent" 79 android:layout_height="match_parent" 80 android:orientation="vertical" 81 android:visibility="visible"> 82 </LinearLayout> 83 <!--数据中心--> 84 <LinearLayout 85 android:id="@+id/displayPage" 86 android:layout_width="match_parent" 87 android:layout_height="match_parent" 88 android:orientation="vertical" 89 android:visibility="gone"> 90 </LinearLayout> 91 </LinearLayout>
四.具体代码实现
-
MainActivity
1 package com.example.john.esdc;
2
3 import android.app.Activity;
4 import android.bluetooth.BluetoothAdapter;
5 import android.bluetooth.BluetoothDevice;
6 import android.content.Intent;
7 import android.os.Handler;
8 import android.os.Message;
9 import android.support.v7.app.AppCompatActivity;
10 import android.os.Bundle;
11 import android.view.Menu;
12 import android.view.MenuItem;
13 import android.view.View;
14 import android.widget.Button;
15 import android.widget.EditText;
16 import android.widget.TextView;
17 import android.widget.Toast;
18
19 public class MainActivity extends AppCompatActivity {
20
21 // Intent request codes
22 private static final int REQUEST_CONNECT_DEVICE = 1;
23 // Local Bluetooth adapter
24 private BluetoothAdapter mBluetoothAdapter = null;
25 // Member object for the chat services
26 private BluetoothChatService mChatService = null;
27 // Message types sent from the BluetoothChatService Handler
28 public static final int MESSAGE_STATE_CHANGE = 1;
29 public static final int MESSAGE_READ = 2;
30 public static final int MESSAGE_WRITE = 3;
31 public static final int MESSAGE_DEVICE_NAME = 4;
32 public static final int MESSAGE_TOAST = 5;
33 // Key names received from the BluetoothChatService Handler
34 public static final String DEVICE_NAME = "device_name";
35 public static final String TOAST = "toast";
36 // Name of the connected device
37 private String mConnectedDeviceName = null;
38 //控件
39 TextView deviceTextView;
40 TextView stateTextView;
41 EditText messageEditText;
42 Button sendButton;
43 TextView displayTextView;
44 private int numofMessage=0; //显示的消息数
45 //界面
46 View controlPage;
47 View displayPage;
48 View chatPage;
49
50
51 @Override
52 protected void onCreate(Bundle savedInstanceState) {
53 super.onCreate(savedInstanceState);
54 setContentView(R.layout.activity_main);
55 getWidget();
56 // Initialize the BluetoothChatService to perform bluetooth connections
57 mChatService = new BluetoothChatService(this, mHandler);
58 // Get local Bluetooth adapter
59 mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
60 sendButton.setOnClickListener(new View.OnClickListener() {
61 @Override
62 public void onClick(View v) {
63 String message = messageEditText.getText().toString();
64 sendMessage(message);
65 }
66 });
67 }
68 //获取控件对象
69 private void getWidget(){
70 deviceTextView = (TextView)findViewById(R.id.DeviceTextView);
71 stateTextView = (TextView)findViewById(R.id.StateTextView);
72 messageEditText = (EditText)findViewById(R.id.MessageEditText);
73 sendButton = (Button)findViewById(R.id.SendButton);
74 displayTextView = (TextView)findViewById(R.id.DisplayTextView);
75
76 chatPage = (View)findViewById(R.id.chatPage);
77 controlPage = (View)findViewById(R.id.controlPage);
78 displayPage = (View)findViewById(R.id.displayPage);
79 }
80 //发送一条消息
81 private void sendMessage(String message){
82 if (mChatService.getState()!=BluetoothChatService.STATE_CONNECTED){
83 Toast.makeText(this, "未连接蓝牙设备", Toast.LENGTH_SHORT).show();
84 return;
85 }
86 if (message.length()>0){
87 byte[] send = message.getBytes();
88 mChatService.write(send);
89 messageEditText.setText("");
90 }
91 }
92 //*********************************************************************************
93 //建立菜单
94 @Override
95 public boolean onCreateOptionsMenu(Menu menu) {
96 getMenuInflater().inflate(R.menu.option_menu,menu);
97 return true;
98 }
99 //菜单响应事件,主要完成界面切换
100 @Override
101 public boolean onOptionsItemSelected(MenuItem item) {
102 switch (item.getItemId()){
103 case R.id.scan: //点击“Scan”项，执行DeviceListActivity，在onActivityResult中返回用户点击连接的蓝牙MAC地址
104 Intent serverIntent = new Intent(this,DeviceListActivity.class);
105 startActivityForResult(serverIntent,REQUEST_CONNECT_DEVICE);
106 return true;
107 case R.id.chatPage:
108 chatPage.setVisibility(View.VISIBLE);
109 displayPage.setVisibility(View.GONE);
110 controlPage.setVisibility(View.GONE);
111 return true;
112 case R.id.displayPage:
113 chatPage.setVisibility(View.GONE);
114 displayPage.setVisibility(View.VISIBLE);
115 controlPage.setVisibility(View.GONE);
116 return true;
117 case R.id.controlPage:
118 chatPage.setVisibility(View.GONE);
119 displayPage.setVisibility(View.GONE);
120 controlPage.setVisibility(View.VISIBLE);
121 return true;
122 }
123 return false;
124 }
125 //**********************************************************************************************
126 //获得DeviceList活动反馈回的蓝牙设备地址，获取BluetoothDevice，开始连接
127 @Override
128 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
129 switch (requestCode){
130 case REQUEST_CONNECT_DEVICE:
131 //获取蓝牙地址并执行连接
132 if(resultCode== Activity.RESULT_OK){
133 String address = data.getExtras()
134 .getString(DeviceListActivity.EXTRA_DEVICE_ADDRESS);
135 BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
136 mChatService.connect(device);
137
138 }
139 }
140 }
141 //**********************************************************************************************
142 //主要负责更新UI
143 private final Handler mHandler = new Handler(){
144 @Override
145 public void handleMessage(Message msg) {
146
147 switch (msg.what){
148 case MESSAGE_STATE_CHANGE:
149 switch (msg.arg1){
150 case BluetoothChatService.STATE_CONNECTED:
151 stateTextView.setText("状态：已连接");
152 break;
153 case BluetoothChatService.STATE_CONNECTING:
154 stateTextView.setText("状态：正连接");
155 break;
156 case BluetoothChatService.STATE_NONE:
157 stateTextView.setText("状态：未连接");
158 break;
159 }
160 break;
161 case MESSAGE_TOAST:
162 Toast.makeText(getApplicationContext(), msg.getData().getString(TOAST),
163 Toast.LENGTH_SHORT).show();
164 break;
165 case MESSAGE_DEVICE_NAME:
166 mConnectedDeviceName = msg.getData().getString(DEVICE_NAME);
167 deviceTextView.setText("设备："+mConnectedDeviceName);
168 Toast.makeText(MainActivity.this, "已连接上"+mConnectedDeviceName, Toast.LENGTH_SHORT).show();
169 break;
170 case MESSAGE_READ:
171 if (chatPage.getVisibility() == View.VISIBLE){
172 displayTextView.append(mConnectedDeviceName+"："+msg.obj+"\n");
173 numofMessage++;
174 if (numofMessage==10) {
175 displayTextView.setText("");
176 numofMessage = 0;
177 }
178 }
179 break;
180 case MESSAGE_WRITE:
181 byte[] writeBuf = (byte[]) msg.obj;
182 String writeMessage = new String(writeBuf);
183 if (chatPage.getVisibility() == View.VISIBLE){
184 displayTextView.append("本机："+writeMessage+"\n");
185 numofMessage++;
186 if (numofMessage==10) {
187 displayTextView.setText("");
188 numofMessage = 0;
189 }
190 }
191 break;
192 }
193 }
194 };
195 }
-
DeviceListActivity
1 package com.example.john.esdc;
2 import android.annotation.SuppressLint;
3 import android.app.Activity;
4 import android.bluetooth.BluetoothAdapter;
5 import android.bluetooth.BluetoothDevice;
6 import android.content.BroadcastReceiver;
7 import android.content.Context;
8 import android.content.Intent;
9 import android.content.IntentFilter;
10 import android.support.v7.app.AppCompatActivity;
11 import android.os.Bundle;
12 import android.view.View;
13 import android.view.Window;
14 import android.widget.AdapterView;
15 import android.widget.ArrayAdapter;
16 import android.widget.ListView;
17 import android.widget.TextView;
18 import android.widget.Toast;
19
20 import java.util.Set;
21
22 import static android.R.attr.filter;
23 @SuppressLint("NewApi")
24 public class DeviceListActivity extends AppCompatActivity {
25
26 // Return Intent extra
27 public static String EXTRA_DEVICE_ADDRESS = "device_address";
28
29 // Member fields
30 private BluetoothAdapter mBtAdapter;
31 private ArrayAdapter<String> mPairedDevicesArrayAdapter;
32 private ArrayAdapter<String> mNewDevicesArrayAdapter;
33
34 @Override
35 protected void onCreate(Bundle savedInstanceState) {
36 super.onCreate(savedInstanceState);
37 setContentView(R.layout.activity_device_list);
38 setResult(Activity.RESULT_CANCELED);
39 // 获取本地蓝牙适配器
40 mBtAdapter = BluetoothAdapter.getDefaultAdapter();
41 mBtAdapter.enable(); //打开蓝牙
42 doDiscovery(); //开始搜索蓝牙设备
43
44
45 //ListView控件适配器组装
46 mPairedDevicesArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
47 mNewDevicesArrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1);
48 ListView pairedListView = (ListView)findViewById(R.id.paired_devices);
49 pairedListView.setAdapter(mPairedDevicesArrayAdapter);
50 pairedListView.setOnItemClickListener(mDeviceClickListener1);
51 ListView newDevicesListView = (ListView)findViewById(R.id.new_devices);
52 newDevicesListView.setAdapter(mNewDevicesArrayAdapter);
53 newDevicesListView.setOnItemClickListener(mDeviceClickListener2);
54
55 //注册广播
56 IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
57 this.registerReceiver(mReceive,filter);
58 filter = new IntentFilter((BluetoothAdapter.ACTION_DISCOVERY_FINISHED));
59 this.registerReceiver(mReceive,filter);
60
61 //获得已配对的蓝牙设备
62 Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();
63 if (pairedDevices.size()>0) {
64 for (BluetoothDevice device : pairedDevices) {
65 mPairedDevicesArrayAdapter.add(device.getName() + "\n" + device.getAddress());
66 }
67 }
68 else{
69 mPairedDevicesArrayAdapter.add("无已配对设备");
70 }
71
72 }
73
74 //蓝牙设备列表的点击响应
75 private AdapterView.OnItemClickListener mDeviceClickListener1 = new AdapterView.OnItemClickListener() {
76 @Override
77 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
78 mBtAdapter.cancelDiscovery();
79 //获取蓝牙设备的MAC地址返回到主活动
80 String info = mPairedDevicesArrayAdapter.getItem(position);
81 String address = info.substring(info.length()-17);
82 Intent intent = new Intent();
83 intent.putExtra(EXTRA_DEVICE_ADDRESS,address);
84 setResult(Activity.RESULT_OK,intent);
85 finish();
86
87
88
89 }
90 };
91 private AdapterView.OnItemClickListener mDeviceClickListener2 = new AdapterView.OnItemClickListener() {
92 @Override
93 public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
94 mBtAdapter.cancelDiscovery();
95 //获取蓝牙设备的MAC地址返回到主活动
96 String info = mNewDevicesArrayAdapter.getItem(position);
97 String address = info.substring(info.length()-17);
98 //Toast.makeText(DeviceListActivity.this, address, Toast.LENGTH_SHORT).show();
99 Intent intent = new Intent();
100 intent.putExtra(EXTRA_DEVICE_ADDRESS,address);
101 setResult(Activity.RESULT_OK,intent);
102 finish();
103
104
105
106 }
107 };
108
109 private void doDiscovery(){
110 setTitle("扫描中，请稍等……");
111 if (mBtAdapter.isDiscovering()){
112 mBtAdapter.cancelDiscovery();
113 }
114 mBtAdapter.startDiscovery();
115 }
116
117
118 @Override
119 protected void onDestroy() {
120 super.onDestroy();
121 // Make sure we‘re not doing discovery anymore
122 if (mBtAdapter != null) {
123 mBtAdapter.cancelDiscovery();
124 }
125 // Unregister broadcast listeners
126 this.unregisterReceiver(mReceive);
127 }
128 //广播监听，当发现新设备时将其添加至列表
129 private final BroadcastReceiver mReceive = new BroadcastReceiver() {
130 @Override
131 public void onReceive(Context context, Intent intent) {
132 String action = intent.getAction();
133 if(BluetoothDevice.ACTION_FOUND.equals(action)){
134 BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
135 if (device.getBondState()!=BluetoothDevice.BOND_BONDED){
136 mNewDevicesArrayAdapter.add(device.getName()+"\n"+device.getAddress());
137 }
138 }else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)){
139 setTitle("请点击设备进行连接：");
140 if(mNewDevicesArrayAdapter.getCount() == 0){
141 mNewDevicesArrayAdapter.add("没有搜索到新设备");
142 }
143 }
144
145 }
146 };
147 }
-
BluetoothChatService
1 package com.example.john.esdc;
2
3 import android.annotation.SuppressLint;
4 import android.app.Notification;
5 import android.bluetooth.BluetoothAdapter;
6 import android.bluetooth.BluetoothDevice;
7 import android.bluetooth.BluetoothSocket;
8 import android.content.Context;
9 import android.os.Bundle;
10 import android.os.Handler;
11 import android.os.Message;
12 import android.util.Log;
13 import android.widget.Toast;
14
15 import java.io.BufferedReader;
16 import java.io.IOException;
17 import java.io.InputStream;
18 import java.io.InputStreamReader;
19 import java.io.OutputStream;
20 import java.util.UUID;
21
22 /**
23 * Created by john on 2017/2/21.
24 */
25
26 @SuppressLint("NewApi")
27 public class BluetoothChatService {
28
29 // Unique UUID for this application
30 private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
31 // Member fields
32 private final BluetoothAdapter mAdapter;
33 private final Handler mHandler;
34 private int mState;
35 private ConnectThread mConnectThread;
36 private ConnectedThread mConnectedThread;
37 private OutputStream mmOutStream=null;
38
39 // Constants that indicate the current connection state
40 public static final int STATE_NONE = 0; // we‘re doing nothing
41 public static final int STATE_LISTEN = 1; // now listening for incoming connections
42 public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
43 public static final int STATE_CONNECTED = 3; // now connected to a remote device
44
45 //构造函数
46 public BluetoothChatService(Context context,Handler handler){
47 mAdapter = BluetoothAdapter.getDefaultAdapter();
48 mState = STATE_NONE;
49 mHandler = handler;
50 }
51 //设置蓝牙状态并且通过Hander通知UI更新状态
52 private synchronized void setState(int state){
53 mState = state;
54 Message message = new Message();
55 message.what = MainActivity.MESSAGE_STATE_CHANGE;
56 message.arg1 = state;
57 mHandler.sendMessage(message);
58 }
59 public synchronized int getState(){
60 return mState;
61 }
62
63 //停止所有线程
64 public synchronized void stop() {
65 if (mConnectThread != null) {mConnectThread.cancel(); mConnectThread = null;}
66 if (mConnectedThread != null) {mConnectedThread.cancel(); mConnectedThread = null;}
67 setState(STATE_NONE);
68 }
69 //连接失败函数，通过UI发出“连接失败”的Toast
70 private void connectionFailed() {
71 setState(STATE_NONE);
72 // Send a failure message back to the Activity
73 Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
74 Bundle bundle = new Bundle();
75 bundle.putString(MainActivity.TOAST, "连接失败");
76 msg.setData(bundle);
77 mHandler.sendMessage(msg);
78 }
79 //连接丢失函数，通过UI发出“连接丢失”的Toast
80 private void connectionLost() {
81 setState(STATE_NONE);
82
83 // Send a failure message back to the Activity
84 Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
85 Bundle bundle = new Bundle();
86 bundle.putString(MainActivity.TOAST, "连接丢失");
87 msg.setData(bundle);
88 mHandler.sendMessage(msg);
89 }
90 private void sendFailed(){
91 Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_TOAST);
92 Bundle bundle = new Bundle();
93 bundle.putString(MainActivity.TOAST, "发送失败");
94 msg.setData(bundle);
95 mHandler.sendMessage(msg);
96 }
97 //连接函数
98 public synchronized void connect(BluetoothDevice device){
99 mConnectThread = new ConnectThread(device);
100 mConnectThread.start();
101 setState(STATE_CONNECTING);
102 }
103 //连接线程类
104 private class ConnectThread extends Thread{
105 private final BluetoothSocket mmSocket;
106 private final BluetoothDevice mmDevice;
107 //构造函数，获得BluetoothDevice，BluetoothSocket
108 public ConnectThread(BluetoothDevice device){
109 mmDevice = device;
110 BluetoothSocket tmp = null;
111 try{
112 tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
113 }catch (IOException e){
114 connectionFailed();
115 }
116 mmSocket = tmp;
117 }
118 //连接线程的执行逻辑，连接成功后转到ConnectedThraed
119 public void run(){
120 mAdapter.cancelDiscovery();
121 try{
122 mmSocket.connect();
123 }catch (IOException e){
124 connectionFailed();
125 try{
126 mmSocket.close();
127 }catch (IOException e2){
128 }
129 return;
130 }
131 //此处开始connected线程
132 connected(mmSocket, mmDevice);
133
134 }
135 public void cancel(){
136 try{
137 mmSocket.close();
138 }catch (IOException e){
139
140 }
141 }
142 }
143 //开始已连接线程,发消息通知主活动更新UI
144 public synchronized void connected(BluetoothSocket socket,BluetoothDevice device){
145
146 mConnectedThread = new ConnectedThread(socket);
147 mConnectedThread.start();
148
149 Message msg = mHandler.obtainMessage(MainActivity.MESSAGE_DEVICE_NAME);
150 Bundle bundle = new Bundle();
151 bundle.putString(MainActivity.DEVICE_NAME,device.getName());
152 msg.setData(bundle);
153 mHandler.sendMessage(msg);
154 setState(STATE_CONNECTED);
155 }
156 //已连接线程类
157 private class ConnectedThread extends Thread{
158 private final BluetoothSocket mmSocket;
159 private final InputStream mmInStream;
160 //构造函数，获取InputStream，OutputStream
161 public ConnectedThread(BluetoothSocket socket){
162 mmSocket = socket;
163 InputStream tmpIn = null;
164 OutputStream tmpOut = null;
165 //获取BluetoothSocket的输入输出流
166 try{
167 tmpIn = socket.getInputStream();
168 tmpOut = socket.getOutputStream();
169 }catch (IOException e){
170
171 }
172 mmInStream = tmpIn;
173 mmOutStream = tmpOut;
174 }
175 //已连接线程的执行逻辑，连接之后持续监听InputStream进行读取
176 public void run() {
177 while (true){
178 try{
179 byte[] arrayOfByte = new byte[1024];
180 int length = 0;
181 length = mmInStream.read(arrayOfByte);
182 Message msg = new Message();
183 msg.what = MainActivity.MESSAGE_READ;
184 msg.obj = new String(arrayOfByte,0,length);
185 mHandler.sendMessage(msg);
186
187 }catch (IOException e){
188 connectionLost();
189 return;
190 }
191 }
192 }
193
194 public void cancel(){
195 try{
196 mmSocket.close();
197 }catch (IOException e){
198
199 }
200 }
201 }
202 //写OutputStream函数，被Send按钮触发sendMessage调用
203 public void write(byte[] buffer){
204 try{
205 mmOutStream.write(buffer);
206 mHandler.obtainMessage(MainActivity.MESSAGE_WRITE,-1,-1,buffer).sendToTarget();
207 }catch (IOException e){
208 return;
209 }
210 }
211 }
五.Debug
六.运行效果
时间： 2024-03-01 02:03:52