<p我运行这个程序，它不能正常工作我想找到附近设备的名称，但蓝牙设备不启动，直到我从通知面板上点击蓝牙按钮，在日志中显示发现开始，并给出另一个日志，显示发现完成而不搜索设备。>
package com.aditya.bluetoothfinder;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
ListView listView;
TextView statusTextView;
Button searchButton;
BluetoothAdapter bluetoothAdapter;//The BluetoothAdapter is required for any and all Bluetooth activity
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = findViewById(R.id.listView);
statusTextView = findViewById(R.id.statusTextView);
searchButton = findViewById(R.id.searchButton);
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
}
public void searchClicked(View view) {
if (bluetoothSupported()) {
openBluetooth();
} else {
statusTextView.setText("Bluetooth Not Supported");
}
}
//This function will check that the bluetooth is supported on the device or not
public boolean bluetoothSupported() {
return getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH);
}
//This function opens the bluetooth
public void openBluetooth() {
if (!bluetoothAdapter.isEnabled()) {
Intent enableBluetoothIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
requestThePermissons();
} else {
startActivityForResult(enableBluetoothIntent, 1);
}
} else {
searchBluetoothDevices();
}
}
//This function request the permission
private void requestThePermissons() {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) { //if we don't have any permission
requestPermissionLauncher.launch(Manifest.permission.BLUETOOTH_CONNECT);
} else { //if we already have permissionn of bluetooth connect
searchBluetoothDevices();
}
}
//This is a callback which give us the information that the user gave us the permission or not
private final ActivityResultLauncher<String> requestPermissionLauncher = registerForActivityResult(new ActivityResultContracts.RequestPermission(), isGranted -> {
if (isGranted) {
// Permission is granted. Continue the action or workflow in your
searchBluetoothDevices();
} else { //If user declined the permission request
Toast.makeText(this, "Permission Denied", Toast.LENGTH_SHORT).show();
}
});
//This is the function for searching bluetooth devices
public void searchBluetoothDevices() {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, "Unable to locate bluetooth device", Toast.LENGTH_SHORT).show();
requestPermissions(new String[]{Manifest.permission.BLUETOOTH_SCAN},1);
} else {
IntentFilter filter = new IntentFilter();
filter.addAction(BluetoothAdapter.ACTION_STATE_CHANGED);
filter.addAction(BluetoothDevice.ACTION_FOUND);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
filter.addAction(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
registerReceiver(receiver, filter);
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, "Unable to locate", Toast.LENGTH_SHORT).show();
}
bluetoothAdapter.startDiscovery();
statusTextView.setText("Searching...");
searchButton.setEnabled(false);
}
}
调用bluetoothAdapter.startDiscovery();
D/BluetoothAdapter: startDiscovery():由:com.aditya.bluetoothfinder调用
但是没有显示日志Discovery started直到我点击通知面板上的蓝牙按钮，之后它会给出另一个日志发现完成
//This function give us the details of the bluetooth device if found
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
Log.i("this", "Device Found");
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
requestThePermissons();
Toast.makeText(MainActivity.this, "Unable to find", Toast.LENGTH_SHORT).show();
} else {
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
String text = (String) statusTextView.getText();
statusTextView.setText(text + "n" +deviceName + "n" + deviceHardwareAddress);
}
} else if(BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
Log.i("this", "Discovery Finished");
statusTextView.setText("Finished");
searchButton.setEnabled(true);
} else if(BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
Log.i("this", "Discovery started");
Toast.makeText(MainActivity.this, "Started", Toast.LENGTH_SHORT).show();
}
}
};
}
AndroidManifest.xml中使用的权限
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_SCAN"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-feature android:name="android.hardware.bluetooth" android:required="true"/>
您还必须获得用户的位置许可，并且用户必须打开位置服务才能看到其他蓝牙设备。