我已经构建了一个与蓝牙模块交互的应用程序。它工作很多次，但有时显示“无法连接”。重新启动手机可以解决问题。当我尝试用于测试的现有BlueTerm应用程序时，同样的事情发生了。有人使用“后备方法”纠正了它，并且应用程序以“BlueTerm_RM”的形式提供，它始终连接。
任何人都可以指出什么是确切的问题以及回退方法的代码更改应该是什么？
MainActivity.java：
package com.example.bluetooth;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.Method;
import java.util.UUID;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity {
int red_count=0;
int yellow_count=0;
int green_count=0;
int white_count=0;
private static final String TAG = "bluetooth2";
Button red_button,yellow_button,green_button,white_button,reset_button;
Handler h;
final int RECIEVE_MESSAGE = 1; // Status for Handler
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder sb = new StringBuilder();
private ConnectedThread mConnectedThread;
// SPP UUID service
private static final UUID MY_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// MAC-address of Bluetooth module (you must edit this line)
private static String address = "20:13:01:18:05:08";
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
red_button = (Button) findViewById(R.id.red_button);
yellow_button = (Button) findViewById(R.id.yellow_button);
green_button = (Button) findViewById(R.id.green_button);
white_button = (Button) findViewById(R.id.white_button);
reset_button = (Button) findViewById(R.id.reset_button);
h = new Handler() {
public void handleMessage(android.os.Message msg) {
switch (msg.what) {
case RECIEVE_MESSAGE: // if receive massage
byte[] readBuf = (byte[]) msg.obj;
String strIncom = new String(readBuf, 0, msg.arg1); // create string from bytes array
sb.append(strIncom); // append string
int endOfLineIndex = sb.indexOf("\r\n"); // determine the end-of-line
if (endOfLineIndex > 0) { // if end-of-line,
sb.delete(0, sb.length()); // and clear
red_button.setEnabled(true);
yellow_button.setEnabled(true);
green_button.setEnabled(true);
white_button.setEnabled(true);
}
//Log.d(TAG, "...String:"+ sb.toString() + "Byte:" + msg.arg1 + "...");
break;
}
};
};
btAdapter = BluetoothAdapter.getDefaultAdapter(); // get Bluetooth adapter
checkBTState();
red_button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
red_count++;
yellow_count=0;
green_count=0;
white_count=0;
red_button.setText(""+red_count);
yellow_button.setText("");
green_button.setText("");
white_button.setText("");
mConnectedThread.write("1"); // Send "1" via Bluetooth
}
});
yellow_button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
yellow_count++;
red_count=0;
green_count=0;
white_count=0;
yellow_button.setText(""+yellow_count);
red_button.setText("");
green_button.setText("");
white_button.setText("");
mConnectedThread.write("2"); // Send "2" via Bluetooth
}
});
green_button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
green_count++;
red_count=0;
yellow_count=0;
white_count=0;
green_button.setText(""+green_count);
red_button.setText("");
yellow_button.setText("");
white_button.setText("");
mConnectedThread.write("3"); // Send "3" via Bluetooth
}
});
white_button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
white_count++;
red_count=0;
green_count=0;
yellow_count=0;
white_button.setText(""+white_count);
red_button.setText("");
green_button.setText("");
yellow_button.setText("");
mConnectedThread.write("4"); // Send "4" via Bluetooth
}
});
reset_button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
white_count=0;
red_count=0;
green_count=0;
yellow_count=0;
white_button.setText("");
red_button.setText("");
green_button.setText("");
yellow_button.setText("");
mConnectedThread.write("0"); // Send "0" via Bluetooth
}
});
}
private BluetoothSocket createBluetoothSocket(BluetoothDevice device) throws IOException {
if(Build.VERSION.SDK_INT >= 10){
try {
final Method m = device.getClass().getMethod("createInsecureRfcommSocketToServiceRecord", new Class[] { UUID.class });
return (BluetoothSocket) m.invoke(device, MY_UUID);
} catch (Exception e) {
Log.e(TAG, "Could not create Insecure RFComm Connection",e);
}
}
return device.createRfcommSocketToServiceRecord(MY_UUID);
}
@Override
public void onResume() {
super.onResume();
Log.d(TAG, "...onResume - try connect...");
// Set up a pointer to the remote node using it's address.
BluetoothDevice device = btAdapter.getRemoteDevice(address);
// Two things are needed to make a connection:
// A MAC address, which we got above.
// A Service ID or UUID. In this case we are using the
// UUID for SPP.
try {
btSocket = createBluetoothSocket(device);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create failed: " + e.getMessage() + ".");
}
/*try {
btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
} catch (IOException e) {
errorExit("Fatal Error", "In onResume() and socket create failed: " + e.getMessage() + ".");
}*/
// Discovery is resource intensive. Make sure it isn't going on
// when you attempt to connect and pass your message.
btAdapter.cancelDiscovery();
// Establish the connection. This will block until it connects.
Log.d(TAG, "...Connecting...");
try {
btSocket.connect();
Log.d(TAG, "....Connection ok...");
} catch (IOException e) {
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onResume() and unable to close socket during connection failure" + e2.getMessage() + ".");
}
}
// Create a data stream so we can talk to server.
Log.d(TAG, "...Create Socket...");
mConnectedThread = new ConnectedThread(btSocket);
mConnectedThread.start();
}
@Override
public void onPause() {
super.onPause();
Log.d(TAG, "...In onPause()...");
try {
btSocket.close();
} catch (IOException e2) {
errorExit("Fatal Error", "In onPause() and failed to close socket." + e2.getMessage() + ".");
}
}
private void checkBTState() {
// Check for Bluetooth support and then check to make sure it is turned on
// Emulator doesn't support Bluetooth and will return null
if(btAdapter==null) {
errorExit("Fatal Error", "Bluetooth not support");
} else {
if (btAdapter.isEnabled()) {
Log.d(TAG, "...Bluetooth ON...");
} else {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, 1);
}
}
}
private void errorExit(String title, String message){
Toast.makeText(getBaseContext(), title + " - " + message, Toast.LENGTH_LONG).show();
finish();
}
private class ConnectedThread extends Thread {
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket 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[256]; // 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); // Get number of bytes and message in "buffer"
h.obtainMessage(RECIEVE_MESSAGE, bytes, -1, buffer).sendToTarget(); // Send to message queue Handler
} catch (IOException e) {
break;
}
}
}
/* Call this from the main activity to send data to the remote device */
public void write(String message) {
Log.d(TAG, "...Data to send: " + message + "...");
byte[] msgBuffer = message.getBytes();
try {
mmOutStream.write(msgBuffer);
} catch (IOException e) {
Log.d(TAG, "...Error data send: " + e.getMessage() + "...");
}
}
}
}