我正在尝试创建蓝牙连接。
我可以搜索附近的设备，但当我尝试连接时，我收到一个我不明白的错误：
连接失败时出现以下错误
connect_error，读取失败，socket可能关闭或超时，读取ret： -1，java.io.IOException：读取失败，套接字可能关闭或超时，读取ret：-1
蓝牙打印服务.java
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.UUID;
/**
* This class does all the work for setting up and managing Bluetooth connections with printers.
* It has a thread for connecting with a printer, and a thread for performing data transmissions when connected.
*/
public class BluetoothPrintService {
// Debugging
private static final String TAG = "BluetoothPrintService";
private static final boolean D = true;
// Unique UUID for this application
private static final UUID SPP_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");
// Member fields
private final BluetoothAdapter mAdapter;
private final Handler mHandler;
private int mState;
private ConnectThread mConnectThread;
private ConnectedThread mConnectedThread;
// Constants that indicate the current connection state
public static final int STATE_NONE = 0; // we're doing nothing
public static final int STATE_LISTEN = 1; // now listening for incoming connections
public static final int STATE_CONNECTING = 2; // now initiating an outgoing connection
public static final int STATE_CONNECTED = 3; // now connected to a remote device
/**
* Constructor. Prepares a new Bluetooth session.
* @param context The UI Activity Context
* @param handler A Handler to send messages back to the UI Activity
*/
public BluetoothPrintService(Context context, Handler handler) {
mAdapter = BluetoothAdapter.getDefaultAdapter();
mState = STATE_NONE;
mHandler = handler;
}
/**
* Set the current state of the 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;
}
/**
* Return the current connection state.
*/
public synchronized int getState() {
return mState;
}
/**
* Start the print service. 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;
}
setState(STATE_LISTEN);
}
/**
* Start the ConnectThread to initiate a connection to a remote device.
* @param device The BluetoothDevice to connect
* @param secure Socket Security type - Secure (true) , Insecure (false)
*/
public synchronized void connect(BluetoothDevice device, boolean secure) {
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, secure);
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, final String socketType) {
if (D) Log.d(TAG, "connected, Socket Type:" + socketType);
// 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;
}
// Start the thread to manage the connection and perform transmissions
mConnectedThread = new ConnectedThread(socket, socketType);
mConnectedThread.start();
// Send the name of the connected device back to the UI Activity
Message msg = mHandler.obtainMessage(WoosimPrnMng.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(WoosimPrnMng.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;
}
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() {
// When the application is destroyed, just return
if (mState == STATE_NONE) return;
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(WoosimPrnMng.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putInt(WoosimPrnMng.TOAST, R.string.connect_fail);
msg.setData(bundle);
mHandler.sendMessage(msg);
// Start the service over to restart listening mode
BluetoothPrintService.this.start();
}
/**
* Indicate that the connection was lost and notify the UI Activity.
*/
private void connectionLost() {
// When the application is destroyed, just return
if (mState == STATE_NONE) return;
// Send a failure message back to the Activity
Message msg = mHandler.obtainMessage(WoosimPrnMng.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putInt(WoosimPrnMng.TOAST, R.string.connect_lost);
msg.setData(bundle);
mHandler.sendMessage(msg);
// Start the service over to restart listening mode
BluetoothPrintService.this.start();
}
/**
* 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;
private String mSocketType;
public ConnectThread(BluetoothDevice device, boolean secure) {
mmDevice = device;
BluetoothSocket tmp = null;
mSocketType = secure ? "Secure" : "Insecure";
// Get a BluetoothSocket for a connection with the
// given BluetoothDevice
try {
if (secure) {
tmp = device.createRfcommSocketToServiceRecord(SPP_UUID);
} else {
tmp = device.createInsecureRfcommSocketToServiceRecord(SPP_UUID);
}
} catch (IOException e) {
Log.e(TAG, "Socket Type: " + mSocketType + "create() failed", e);
}
mmSocket = tmp;
}
public void run() {
Log.i(TAG, "BEGIN mConnectThread SocketType:" + mSocketType);
setName("ConnectThread" + mSocketType);
// 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) {
// Close the socket
try {
mmSocket.close();
} catch (IOException e2) {
Log.e(TAG, "unable to close() " + mSocketType + " socket during connection failure", e2);
}
Log.e(TAG, "Connection Failed", e);
connectionFailed();
return;
}
// Reset the ConnectThread because we're done
synchronized (BluetoothPrintService.this) {
mConnectThread = null;
}
// Start the connected thread
connected(mmSocket, mmDevice, mSocketType);
}
public void cancel() {
try {
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect " + mSocketType + " socket failed", e);
}
}
}
/**
* This thread runs during a connection with a remote device.
* It handles all incoming and outgoing transmissions.
*/
private class ConnectedThread extends Thread {
private final BluetoothSocket mmSocket;
private final InputStream mmInStream;
private final OutputStream mmOutStream;
public ConnectedThread(BluetoothSocket socket, String socketType) {
Log.d(TAG, "create ConnectedThread: " + socketType);
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);
// buffer can be over-written by next input stream data, so it should be copied
byte[] rcvData = new byte[bytes];
rcvData = Arrays.copyOf(buffer, bytes);
// Send the obtained bytes to the UI Activity
mHandler.obtainMessage(WoosimPrnMng.MESSAGE_READ, bytes, -1, rcvData).sendToTarget();
} catch (IOException e) {
Log.e(TAG, "Connection Lost", e);
connectionLost();
break;
}
}
}
/**
* Write to the connected OutStream.
* @param buffer The bytes to write
*/
public void write(byte[] buffer) {
try {
mmOutStream.write(buffer);
} catch (IOException e) {
Log.e(TAG, "Exception during write", e);
}
}
public void cancel() {
try {
mmInStream.close();
mmOutStream.close();
mmSocket.close();
} catch (IOException e) {
Log.e(TAG, "close() of connect socket failed", e);
}
}
}
}
它会在
connectionFailed我在 Android 13 上也遇到类似问题。
你排除这个可能性了吗？ https://developer.android.com/guide/topics/connectivity/bluetooth/permissions