如何解决为什么我的 Android 应用程序不扫描蓝牙设备？
- 在我的蓝牙应用程序中，我创建了两个按钮，一个用于获取配对设备，另一个用于扫描蓝牙设备。当我单击扫描按钮 Toast 消息显示未找到设备时，代码总是转到我的广播接收器中的其他部分。有人可以向我解释发生了什么* ** MainActivity.java **
package com.example.broadcast;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Set;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final int REQUEST_ENABLE_BT = 2;
private Button scanButton;
private Button discoverButton;
private MyBroadcast broadcast;
private MyBroadcastdiscover broadcastdiscover;
public BluetoothAdapter bluetoothAdapter;
public Set<BluetoothDevice> pairedDevices;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
broadcast=new MyBroadcast();
broadcastdiscover=new MyBroadcastdiscover();
bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
scanButton=(Button) findViewById(R.id.scan_btn);
discoverButton=(Button) findViewById(R.id.discover_btn);
scanButton.setOnClickListener(this);
discoverButton.setOnClickListener(this);
if (bluetoothAdapter == null) {
// Device doesn't support Bluetooth
Toast.makeText(getApplicationContext(),"Device doesn't support bluetooth",Toast.LENGTH_LONG).show();
}
if (!bluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent,REQUEST_ENABLE_BT);
}
}
@Override
protected void onStart() {
super.onStart();
IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(broadcast,filter);
}
@Override
protected void onStop() {
super.onStop();
unregisterReceiver(broadcast);
unregisterReceiver(broadcastdiscover);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(broadcast);
unregisterReceiver(broadcastdiscover);
}
@RequiresApi(api = Build.VERSION_CODES.M)
@Override
public void onClick(View v) {
switch (v.getId())
{
case R.id.scan_btn:
{
pairedDevices = bluetoothAdapter.getBondedDevices();
if (pairedDevices.size() > 0) {
// There are paired devices. Get the name and address of each paired device.
for (BluetoothDevice device : pairedDevices) {
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
ArrayList list = new ArrayList();
list.add(device.getName());
Toast.makeText(getApplicationContext(),deviceName,Toast.LENGTH_LONG).show();
}
break;
}
}
case R.id.discover_btn:
{
Toast.makeText(getApplicationContext(),"SCAN",Toast.LENGTH_LONG).show();
/* Intent discoverableIntent =
new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION,150);
startActivity(discoverableIntent);*/
if (bluetoothAdapter.isDiscovering()) {
bluetoothAdapter.cancelDiscovery();
checkBTPermission();
bluetoothAdapter.startDiscovery();
registerReceiver(broadcastdiscover,new IntentFilter(bluetoothAdapter.ACTION_DISCOVERY_STARTED));
registerReceiver(broadcastdiscover,new IntentFilter(bluetoothAdapter.ACTION_DISCOVERY_FINISHED));
}
if(!bluetoothAdapter.isDiscovering())
{
bluetoothAdapter.startDiscovery();
registerReceiver(broadcastdiscover,new IntentFilter(bluetoothAdapter.ACTION_DISCOVERY_FINISHED));
}
break;
}
}
}
@RequiresApi(api = Build.VERSION_CODES.M)
private void checkBTPermission() {
if(Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP){
int permissionCheck = this.checkSelfPermission("Manifest.permission.ACCESS_FINE_LOCATION");
permissionCheck += this.checkSelfPermission("Manifest.permission.ACCESS_COARSE_LOCATION");
if (permissionCheck != 0) {
this.requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION,Manifest.permission.ACCESS_COARSE_LOCATION},1001); //Any number
}
}else{
Log.d("TAG","checkBTPermissions: No need to check permissions. SDK version < LOLLIPOP.");
}
}
}
** MyBroadcastdiscover.java**
package com.example.broadcast;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;
import java.util.ArrayList;
import static android.content.ContentValues.TAG;
public class MyBroadcastdiscover extends BroadcastReceiver {
public ArrayList<BluetoothDevice> mBTDevices=new ArrayList<>();
@Override
public void onReceive(Context context,Intent intent) {
String action = intent.getAction();
// Toast.makeText(context,action,Toast.LENGTH_LONG).show();
if(action.equals(BluetoothDevice.ACTION_FOUND))
{
// Discovery has found a device. Get the BluetoothDevice
// object and its info from the Intent.
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
String deviceName = device.getName();
String deviceHardwareAddress = device.getAddress(); // MAC address
Toast.makeText(context,Toast.LENGTH_LONG).show();
Log.d("TAG",deviceHardwareAddress);
}
else {
Toast.makeText(context,"NO DEVICE YET FOuND",Toast.LENGTH_LONG).show();
Log.d("TAG","DEVICE NOT FOUND");
}
}
}
** AndroidManifest.xml**
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcast">
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<!-- If your app targets Android 9 or lower,you can declare
ACCESS_COARSE_LOCATION instead. -->
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.Broadcast">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
** activitymain.xml**
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.119" />
<Button
android:id="@+id/scan_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="108dp"
android:text="@string/scanDevice"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView" />
<Button
android:id="@+id/discover_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="92dp"
android:text="@string/scanningdevice"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/scan_btn" />
</androidx.constraintlayout.widget.ConstraintLayout>
解决方法
您必须像这样在 Manifest.xml 中的应用程序中声明服务：
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.Broadcast">
...
<receiver android:name="com.example.broadcast.MyBroadcastdiscover" >
<intent-filter>
<action android:name="android.bluetooth.device.action.ACTION_FOUND" />
</intent-filter>
</receiver>
</application>
版权声明：本文内容由互联网用户自发贡献，该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请发送邮件至 dio@foxmail.com 举报，一经查实，本站将立刻删除。
