blocks|key|131502|text|private+OutputStream+outputStream;
private+InputStream+inStream;

private+void+init()+throws+IOException+{
++++BluetoothAdapter+blueAdapter+=+BluetoothAdapter.getDefaultAdapter();
++++if+(blueAdapter+!=+null)+{
++++++++if+(blueAdapter.isEnabled())+{
++++++++++++Set<BluetoothDevice>+bondedDevices+=+blueAdapter.getBondedDevices();

++++++++++++if(bondedDevices.size()+>+0)+{
++++++++++++++++Object[]+devices+=+(Object+[])+bondedDevices.toArray();
++++++++++++++++BluetoothDevice+device+=+(BluetoothDevice)+devices[position];
++++++++++++++++ParcelUuid[]+uuids+=+device.getUuids();
++++++++++++++++BluetoothSocket+socket+=+device.createRfcommSocketToServiceRecord(uuids[0].getUuid());
++++++++++++++++socket.connect();
++++++++++++++++outputStream+=+socket.getOutputStream();
++++++++++++++++inStream+=+socket.getInputStream();
++++++++++++}

++++++++++++Log.e("error",+"No+appropriate+paired+devices.");
++++++++}+else+{
++++++++++++Log.e("error",+"Bluetooth+is+disabled.");
++++++++}
++++}
}

public+void+write(String+s)+throws+IOException+{
++++outputStream.write(s.getBytes());
}

public+void+run()+{
++++final+int+BUFFER_SIZE+=+1024;
++++byte[]+buffer+=+new+byte[BUFFER_SIZE];
++++int+bytes+=+0;
++++int+b+=+BUFFER_SIZE;

++++while+(true)+{
++++++++try+{
++++++++++++bytes+=+inStream.read(buffer,+bytes,+BUFFER_SIZE+-+bytes);
++++++++}+catch+(IOException+e)+{
++++++++++++e.printStackTrace();
++++++++}
++++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|131503|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>private OutputStream outputStream;
private InputStream inStream;

private void init() throws IOException {
 BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();
 if (blueAdapter != null) {
 if (blueAdapter.isEnabled()) {
 Set&lt;BluetoothDevice&gt; bondedDevices = blueAdapter.getBondedDevices();

 if(bondedDevices.size() &gt; 0) {
 Object[] devices = (Object []) bondedDevices.toArray();
 BluetoothDevice device = (BluetoothDevice) devices[position];
 ParcelUuid[] uuids = device.getUuids();
 BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuids[0].getUuid());
 socket.connect();
 outputStream = socket.getOutputStream();
 inStream = socket.getInputStream();
 }

 Log.e("error", "No appropriate paired devices.");
 } else {
 Log.e("error", "Bluetooth is disabled.");
 }
 }
}

public void write(String s) throws IOException {
 outputStream.write(s.getBytes());
}

public void run() {
 final int BUFFER_SIZE = 1024;
 byte[] buffer = new byte[BUFFER_SIZE];
 int bytes = 0;
 int b = BUFFER_SIZE;

 while (true) {
 try {
 bytes = inStream.read(buffer, bytes, BUFFER_SIZE - bytes);
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
}
</code></pre>

blocks|key|131565|text|我写了下面的代码，这样即使是初学者也能理解。只需复制代码并阅读注释即可。请注意，要发送的消息被声明为一个全局变量，您可以在发送消息之前更改该变量。一般的更改可以在Handler函数中完成。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|131566|multiplayerConnect.java|131567|import+android.annotation.SuppressLint;
import+android.bluetooth.BluetoothAdapter;
import+android.bluetooth.BluetoothDevice;
import+android.bluetooth.BluetoothServerSocket;
import+android.bluetooth.BluetoothSocket;
import+android.content.Intent;
import+android.os.Bundle;
import+android.os.Handler;
import+android.os.Message;
import+android.support.annotation.Nullable;
import+android.support.v7.app.AppCompatActivity;
import+android.view.View;
import+android.widget.AdapterView;
import+android.widget.ArrayAdapter;
import+android.widget.ListView;
import+android.widget.Toast;

import+java.io.IOException;
import+java.io.InputStream;
import+java.io.OutputStream;
import+java.util.ArrayList;
import+java.util.Set;
import+java.util.UUID;

public+class+multiplayerConnect+extends+AppCompatActivity+{

public+static+final+int+REQUEST_ENABLE_BT=1;
ListView+lv_paired_devices;
Set<BluetoothDevice>+set_pairedDevices;
ArrayAdapter+adapter_paired_devices;
BluetoothAdapter+bluetoothAdapter;
public+static+final+UUID+MY_UUID+=+UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
public+static+final+int+MESSAGE_READ=0;
public+static+final+int+MESSAGE_WRITE=1;
public+static+final+int+CONNECTING=2;
public+static+final+int+CONNECTED=3;
public+static+final+int+NO_SOCKET_FOUND=4;


String+bluetooth_message="00";




@SuppressLint("HandlerLeak")
Handler+mHandler=new+Handler()
{
++++@Override
++++public+void+handleMessage(Message+msg_type)+{
++++++++super.handleMessage(msg_type);

++++++++switch+(msg_type.what){
++++++++++++case+MESSAGE_READ:

++++++++++++++++byte[]+readbuf=(byte[])msg_type.obj;
++++++++++++++++String+string_recieved=new+String(readbuf);

++++++++++++++++//do+some+task+based+on+recieved+string

++++++++++++++++break;
++++++++++++case+MESSAGE_WRITE:

++++++++++++++++if(msg_type.obj!=null){
++++++++++++++++++++ConnectedThread+connectedThread=new+ConnectedThread((BluetoothSocket)msg_type.obj);
++++++++++++++++++++connectedThread.write(bluetooth_message.getBytes());

++++++++++++++++}
++++++++++++++++break;

++++++++++++case+CONNECTED:
++++++++++++++++Toast.makeText(getApplicationContext(),"Connected",Toast.LENGTH_SHORT).show();
++++++++++++++++break;

++++++++++++case+CONNECTING:
++++++++++++++++Toast.makeText(getApplicationContext(),"Connecting...",Toast.LENGTH_SHORT).show();
++++++++++++++++break;

++++++++++++case+NO_SOCKET_FOUND:
++++++++++++++++Toast.makeText(getApplicationContext(),"No+socket+found",Toast.LENGTH_SHORT).show();
++++++++++++++++break;
++++++++}
++++}
};



@Override
protected+void+onCreate(@Nullable+Bundle+savedInstanceState)+{
++++super.onCreate(savedInstanceState);
++++setContentView(R.layout.multiplayer_bluetooth);
++++initialize_layout();
++++initialize_bluetooth();
++++start_accepting_connection();
++++initialize_clicks();

}

public+void+start_accepting_connection()
{
++++//call+this+on+button+click+as+suited+by+you

++++AcceptThread+acceptThread+=+new+AcceptThread();
++++acceptThread.start();
++++Toast.makeText(getApplicationContext(),"accepting",Toast.LENGTH_SHORT).show();
}
public+void+initialize_clicks()
{
++++lv_paired_devices.setOnItemClickListener(new+AdapterView.OnItemClickListener()+{
++++++++@Override
++++++++public+void+onItemClick(AdapterView<?>+parent,+View+view,+int+position,+long+id)
++++++++{
++++++++++++Object[]+objects+=+set_pairedDevices.toArray();
++++++++++++BluetoothDevice+device+=+(BluetoothDevice)+objects[position];

++++++++++++ConnectThread+connectThread+=+new+ConnectThread(device);
++++++++++++connectThread.start();

++++++++++++Toast.makeText(getApplicationContext(),"device+choosen+"%2Bdevice.getName(),Toast.LENGTH_SHORT).show();
++++++++}
++++});
}

public+void+initialize_layout()
{
++++lv_paired_devices+=+(ListView)findViewById(R.id.lv_paired_devices);
++++adapter_paired_devices+=+new+ArrayAdapter(getApplicationContext(),R.layout.support_simple_spinner_dropdown_item);
++++lv_paired_devices.setAdapter(adapter_paired_devices);
}

public+void+initialize_bluetooth()
{
++++bluetoothAdapter+=+BluetoothAdapter.getDefaultAdapter();
++++if+(bluetoothAdapter+==+null)+{
++++++++//+Device+doesn't+support+Bluetooth
++++++++Toast.makeText(getApplicationContext(),"Your+Device+doesn't+support+bluetooth.+you+can+play+as+Single+player",Toast.LENGTH_SHORT).show();
++++++++finish();
++++}

++++//Add+these+permisions+before
//++++++++<uses-permission+android:name="android.permission.BLUETOOTH"+/>
//++++++++<uses-permission+android:name="android.permission.BLUETOOTH_ADMIN"+/>
//++++++++<uses-permission+android:name="android.permission.ACCESS_COARSE_LOCATION"+/>
//++++++++<uses-permission+android:name="android.permission.ACCESS_FINE_LOCATION"/>

++++if+(!bluetoothAdapter.isEnabled())+{
++++++++Intent+enableBtIntent+=+new+Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
++++++++startActivityForResult(enableBtIntent,+REQUEST_ENABLE_BT);
++++}

++++else+{
++++++++set_pairedDevices+=+bluetoothAdapter.getBondedDevices();

++++++++if+(set_pairedDevices.size()+>+0)+{

++++++++++++for+(BluetoothDevice+device+:+set_pairedDevices)+{
++++++++++++++++String+deviceName+=+device.getName();
++++++++++++++++String+deviceHardwareAddress+=+device.getAddress();+//+MAC+address

++++++++++++++++adapter_paired_devices.add(device.getName()+%2B+"\n"+%2B+device.getAddress());
++++++++++++}
++++++++}
++++}
}


public+class+AcceptThread+extends+Thread
{
++++private+final+BluetoothServerSocket+serverSocket;

++++public+AcceptThread()+{
++++++++BluetoothServerSocket+tmp+=+null;
++++++++try+{
++++++++++++//+MY_UUID+is+the+app's+UUID+string,+also+used+by+the+client+code
++++++++++++tmp+=+bluetoothAdapter.listenUsingRfcommWithServiceRecord("NAME",MY_UUID);
++++++++}+catch+(IOException+e)+{+}
++++++++serverSocket+=+tmp;
++++}

++++public+void+run()+{
++++++++BluetoothSocket+socket+=+null;
++++++++//+Keep+listening+until+exception+occurs+or+a+socket+is+returned
++++++++while+(true)+{
++++++++++++try+{
++++++++++++++++socket+=+serverSocket.accept();
++++++++++++}+catch+(IOException+e)+{
++++++++++++++++break;
++++++++++++}

++++++++++++//+If+a+connection+was+accepted
++++++++++++if+(socket+!=+null)
++++++++++++{
++++++++++++++++//+Do+work+to+manage+the+connection+(in+a+separate+thread)
++++++++++++++++mHandler.obtainMessage(CONNECTED).sendToTarget();
++++++++++++}
++++++++}
++++}
}


private+class+ConnectThread+extends+Thread+{
++++private+final+BluetoothSocket+mmSocket;
++++private+final+BluetoothDevice+mmDevice;

++++public+ConnectThread(BluetoothDevice+device)+{
++++++++//+Use+a+temporary+object+that+is+later+assigned+to+mmSocket,
++++++++//+because+mmSocket+is+final
++++++++BluetoothSocket+tmp+=+null;
++++++++mmDevice+=+device;

++++++++//+Get+a+BluetoothSocket+to+connect+with+the+given+BluetoothDevice
++++++++try+{
++++++++++++//+MY_UUID+is+the+app's+UUID+string,+also+used+by+the+server+code
++++++++++++tmp+=+device.createRfcommSocketToServiceRecord(MY_UUID);
++++++++}+catch+(IOException+e)+{+}
++++++++mmSocket+=+tmp;
++++}

++++public+void+run()+{
++++++++//+Cancel+discovery+because+it+will+slow+down+the+connection
++++++++bluetoothAdapter.cancelDiscovery();

++++++++try+{
++++++++++++//+Connect+the+device+through+the+socket.+This+will+block
++++++++++++//+until+it+succeeds+or+throws+an+exception
++++++++++++mHandler.obtainMessage(CONNECTING).sendToTarget();

++++++++++++mmSocket.connect();
++++++++}+catch+(IOException+connectException)+{
++++++++++++//+Unable+to+connect;+close+the+socket+and+get+out
++++++++++++try+{
++++++++++++++++mmSocket.close();
++++++++++++}+catch+(IOException+closeException)+{+}
++++++++++++return;
++++++++}

++++++++//+Do+work+to+manage+the+connection+(in+a+separate+thread)
//++++++++++++bluetooth_message+=+"Initial+message"
//++++++++++++mHandler.obtainMessage(MESSAGE_WRITE,mmSocket).sendToTarget();
++++}

++++/**+Will+cancel+an+in-progress+connection,+and+close+the+socket+*/
++++public+void+cancel()+{
++++++++try+{
++++++++++++mmSocket.close();
++++++++}+catch+(IOException+e)+{+}
++++}
}
private+class+ConnectedThread+extends+Thread+{

++++private+final+BluetoothSocket+mmSocket;
++++private+final+InputStream+mmInStream;
++++private+final+OutputStream+mmOutStream;

++++public+ConnectedThread(BluetoothSocket+socket)+{
++++++++mmSocket+=+socket;
++++++++InputStream+tmpIn+=+null;
++++++++OutputStream+tmpOut+=+null;

++++++++//+Get+the+input+and+output+streams,+using+temp+objects+because
++++++++//+member+streams+are+final
++++++++try+{
++++++++++++tmpIn+=+socket.getInputStream();
++++++++++++tmpOut+=+socket.getOutputStream();
++++++++}+catch+(IOException+e)+{+}

++++++++mmInStream+=+tmpIn;
++++++++mmOutStream+=+tmpOut;
++++}

++++public+void+run()+{
++++++++byte[]+buffer+=+new+byte[2];++//+buffer+store+for+the+stream
++++++++int+bytes;+//+bytes+returned+from+read()

++++++++//+Keep+listening+to+the+InputStream+until+an+exception+occurs
++++++++while+(true)+{
++++++++++++try+{
++++++++++++++++//+Read+from+the+InputStream
++++++++++++++++bytes+=+mmInStream.read(buffer);
++++++++++++++++//+Send+the+obtained+bytes+to+the+UI+activity
++++++++++++++++mHandler.obtainMessage(MESSAGE_READ,+bytes,+-1,+buffer).sendToTarget();

++++++++++++}+catch+(IOException+e)+{
++++++++++++++++break;
++++++++++++}
++++++++}
++++}

++++/*+Call+this+from+the+main+activity+to+send+data+to+the+remote+device+*/
++++public+void+write(byte[]+bytes)+{
++++++++try+{
++++++++++++mmOutStream.write(bytes);
++++++++}+catch+(IOException+e)+{+}
++++}

++++/*+Call+this+from+the+main+activity+to+shutdown+the+connection+*/
++++public+void+cancel()+{
++++++++try+{
++++++++++++mmSocket.close();
++++++++}+catch+(IOException+e)+{+}
++++}
}
}|code-block|syntax|javascript|131568|multiplayer_bluetooth.xml|131569|<?xml+version="1.0"+encoding="utf-8"?>
<LinearLayout+xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">

++++<TextView
++++++++android:layout_width="match_parent"
++++++++android:layout_height="wrap_content"
++++++++android:text="Challenge+player"/>

++++<ListView
++++++++android:id="@%2Bid/lv_paired_devices"
++++++++android:layout_width="match_parent"
++++++++android:layout_height="match_parent"
++++++++android:layout_weight="1">
++++</ListView>

++++<TextView
++++++++android:layout_width="match_parent"
++++++++android:layout_height="wrap_content"
++++++++android:text="Make+sure+Device+is+paired"/>

</LinearLayout>|131570|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I made the following code so that even beginners can understand. Just copy the code and read comments. Note that message to be send is declared as a global variable which you can change just before sending the message. General changes can be done in Handler function.
multiplayerConnect.java
<pre><code>import android.annotation.SuppressLint;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Set;
import java.util.UUID;

public class multiplayerConnect extends AppCompatActivity {

public static final int REQUEST_ENABLE_BT=1;
ListView lv_paired_devices;
Set&lt;BluetoothDevice&gt; set_pairedDevices;
ArrayAdapter adapter_paired_devices;
BluetoothAdapter bluetoothAdapter;
public static final UUID MY_UUID = UUID.fromString(&quot;00001101-0000-1000-8000-00805F9B34FB&quot;);
public static final int MESSAGE_READ=0;
public static final int MESSAGE_WRITE=1;
public static final int CONNECTING=2;
public static final int CONNECTED=3;
public static final int NO_SOCKET_FOUND=4;


String bluetooth_message=&quot;00&quot;;




@SuppressLint(&quot;HandlerLeak&quot;)
Handler mHandler=new Handler()
{
 @Override
 public void handleMessage(Message msg_type) {
 super.handleMessage(msg_type);

 switch (msg_type.what){
 case MESSAGE_READ:

 byte[] readbuf=(byte[])msg_type.obj;
 String string_recieved=new String(readbuf);

 //do some task based on recieved string

 break;
 case MESSAGE_WRITE:

 if(msg_type.obj!=null){
 ConnectedThread connectedThread=new ConnectedThread((BluetoothSocket)msg_type.obj);
 connectedThread.write(bluetooth_message.getBytes());

 }
 break;

 case CONNECTED:
 Toast.makeText(getApplicationContext(),&quot;Connected&quot;,Toast.LENGTH_SHORT).show();
 break;

 case CONNECTING:
 Toast.makeText(getApplicationContext(),&quot;Connecting...&quot;,Toast.LENGTH_SHORT).show();
 break;

 case NO_SOCKET_FOUND:
 Toast.makeText(getApplicationContext(),&quot;No socket found&quot;,Toast.LENGTH_SHORT).show();
 break;
 }
 }
};



@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.multiplayer_bluetooth);
 initialize_layout();
 initialize_bluetooth();
 start_accepting_connection();
 initialize_clicks();

}

public void start_accepting_connection()
{
 //call this on button click as suited by you

 AcceptThread acceptThread = new AcceptThread();
 acceptThread.start();
 Toast.makeText(getApplicationContext(),&quot;accepting&quot;,Toast.LENGTH_SHORT).show();
}
public void initialize_clicks()
{
 lv_paired_devices.setOnItemClickListener(new AdapterView.OnItemClickListener() {
 @Override
 public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id)
 {
 Object[] objects = set_pairedDevices.toArray();
 BluetoothDevice device = (BluetoothDevice) objects[position];

 ConnectThread connectThread = new ConnectThread(device);
 connectThread.start();

 Toast.makeText(getApplicationContext(),&quot;device choosen &quot;+device.getName(),Toast.LENGTH_SHORT).show();
 }
 });
}

public void initialize_layout()
{
 lv_paired_devices = (ListView)findViewById(R.id.lv_paired_devices);
 adapter_paired_devices = new ArrayAdapter(getApplicationContext(),R.layout.support_simple_spinner_dropdown_item);
 lv_paired_devices.setAdapter(adapter_paired_devices);
}

public void initialize_bluetooth()
{
 bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
 if (bluetoothAdapter == null) {
 // Device doesn't support Bluetooth
 Toast.makeText(getApplicationContext(),&quot;Your Device doesn't support bluetooth. you can play as Single player&quot;,Toast.LENGTH_SHORT).show();
 finish();
 }

 //Add these permisions before
// &lt;uses-permission android:name=&quot;android.permission.BLUETOOTH&quot; /&gt;
// &lt;uses-permission android:name=&quot;android.permission.BLUETOOTH_ADMIN&quot; /&gt;
// &lt;uses-permission android:name=&quot;android.permission.ACCESS_COARSE_LOCATION&quot; /&gt;
// &lt;uses-permission android:name=&quot;android.permission.ACCESS_FINE_LOCATION&quot;/&gt;

 if (!bluetoothAdapter.isEnabled()) {
 Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
 startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
 }

 else {
 set_pairedDevices = bluetoothAdapter.getBondedDevices();

 if (set_pairedDevices.size() &gt; 0) {

 for (BluetoothDevice device : set_pairedDevices) {
 String deviceName = device.getName();
 String deviceHardwareAddress = device.getAddress(); // MAC address

 adapter_paired_devices.add(device.getName() + &quot;\n&quot; + device.getAddress());
 }
 }
 }
}


public class AcceptThread extends Thread
{
 private final BluetoothServerSocket serverSocket;

 public AcceptThread() {
 BluetoothServerSocket tmp = null;
 try {
 // MY_UUID is the app's UUID string, also used by the client code
 tmp = bluetoothAdapter.listenUsingRfcommWithServiceRecord(&quot;NAME&quot;,MY_UUID);
 } catch (IOException e) { }
 serverSocket = tmp;
 }

 public void run() {
 BluetoothSocket socket = null;
 // Keep listening until exception occurs or a socket is returned
 while (true) {
 try {
 socket = serverSocket.accept();
 } catch (IOException e) {
 break;
 }

 // If a connection was accepted
 if (socket != null)
 {
 // Do work to manage the connection (in a separate thread)
 mHandler.obtainMessage(CONNECTED).sendToTarget();
 }
 }
 }
}


private class ConnectThread extends Thread {
 private final BluetoothSocket mmSocket;
 private final BluetoothDevice mmDevice;

 public ConnectThread(BluetoothDevice device) {
 // Use a temporary object that is later assigned to mmSocket,
 // because mmSocket is final
 BluetoothSocket tmp = null;
 mmDevice = device;

 // Get a BluetoothSocket to connect with the given BluetoothDevice
 try {
 // MY_UUID is the app's UUID string, also used by the server code
 tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
 } catch (IOException e) { }
 mmSocket = tmp;
 }

 public void run() {
 // Cancel discovery because it will slow down the connection
 bluetoothAdapter.cancelDiscovery();

 try {
 // Connect the device through the socket. This will block
 // until it succeeds or throws an exception
 mHandler.obtainMessage(CONNECTING).sendToTarget();

 mmSocket.connect();
 } catch (IOException connectException) {
 // Unable to connect; close the socket and get out
 try {
 mmSocket.close();
 } catch (IOException closeException) { }
 return;
 }

 // Do work to manage the connection (in a separate thread)
// bluetooth_message = &quot;Initial message&quot;
// mHandler.obtainMessage(MESSAGE_WRITE,mmSocket).sendToTarget();
 }

 /** Will cancel an in-progress connection, and close the socket */
 public void cancel() {
 try {
 mmSocket.close();
 } catch (IOException e) { }
 }
}
private class ConnectedThread extends Thread {

 private final BluetoothSocket mmSocket;
 private final InputStream mmInStream;
 private final OutputStream mmOutStream;

 public ConnectedThread(BluetoothSocket socket) {
 mmSocket = socket;
 InputStream tmpIn = null;
 OutputStream tmpOut = null;

 // Get the input and output streams, using temp objects because
 // member streams are final
 try {
 tmpIn = socket.getInputStream();
 tmpOut = socket.getOutputStream();
 } catch (IOException e) { }

 mmInStream = tmpIn;
 mmOutStream = tmpOut;
 }

 public void run() {
 byte[] buffer = new byte[2]; // buffer store for the stream
 int bytes; // bytes returned from read()

 // Keep listening to the InputStream until an exception occurs
 while (true) {
 try {
 // Read from the InputStream
 bytes = mmInStream.read(buffer);
 // Send the obtained bytes to the UI activity
 mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer).sendToTarget();

 } catch (IOException e) {
 break;
 }
 }
 }

 /* Call this from the main activity to send data to the remote device */
 public void write(byte[] bytes) {
 try {
 mmOutStream.write(bytes);
 } catch (IOException e) { }
 }

 /* Call this from the main activity to shutdown the connection */
 public void cancel() {
 try {
 mmSocket.close();
 } catch (IOException e) { }
 }
}
}
</code></pre>
multiplayer_bluetooth.xml
<pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
&lt;LinearLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
android:orientation=&quot;vertical&quot;
android:layout_width=&quot;match_parent&quot;
android:layout_height=&quot;match_parent&quot;&gt;

 &lt;TextView
 android:layout_width=&quot;match_parent&quot;
 android:layout_height=&quot;wrap_content&quot;
 android:text=&quot;Challenge player&quot;/&gt;

 &lt;ListView
 android:id=&quot;@+id/lv_paired_devices&quot;
 android:layout_width=&quot;match_parent&quot;
 android:layout_height=&quot;match_parent&quot;
 android:layout_weight=&quot;1&quot;&gt;
 &lt;/ListView&gt;

 &lt;TextView
 android:layout_width=&quot;match_parent&quot;
 android:layout_height=&quot;wrap_content&quot;
 android:text=&quot;Make sure Device is paired&quot;/&gt;

&lt;/LinearLayout&gt;
</code></pre>

I want to send a simple string data such as 'a' from an android device to other one via bluetooth. I looked sample bluetooth code in android sdk but it is so complex for me. I cannot understand how I can send only specific data when I press a button. How can I solve this problem?

Android sample bluetooth code to send a simple string via bluetooth

我想通过蓝牙将一个简单的字符串数据从一个android设备发送到另一个设备。我在android sdk中查看了蓝牙示例代码，但它对我来说太复杂了。我不明白当我按下一个按钮时，我怎么能只发送特定的数据。我该如何解决这个问题？

问通过蓝牙发送简单字符串的Android示例蓝牙代码
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