android Studio：蓝牙发现功能不再适用于 Android 10？答案

【问题标题】：android Studio: Bluetooth Discovery doesnt work on Android 10 anymore?android Studio：蓝牙发现功能不再适用于 Android 10？
【发布时间】：2020-07-21 14:36:40
【问题描述】：

所以我正在构建一个具有内置蓝牙发现功能的应用程序。现在我正在两部不同的手机上试用：

手机 1：小米 9T Pro / Android 版本：9 = 运行良好
Phone2：POCO F2 PRO / Android 版本：10 = 根本不工作

问题是，当我在电话 1 上试用时，控制台显示发现过程已开始，并向我显示附近有哪些设备，如下所示：

I/Timeline: Timeline: Activity_launch_request time:6873263 intent:Intent { act=android.content.pm.action.REQUEST_PERMISSIONS pkg=com.google.android.packageinstaller (has extras) }
I/System.out: Discoverybool was set to: true
D/MainActivity: onReceive: Action Found
D/MainActivity: onReceive: null: 9C:20:7B:CD:EF:75
D/MainActivity: onReceive: Action Found
D/MainActivity: onReceive: POCO: 98:F6:21:C0:2E:FF
D/MainActivity: onReceive: Action Found
    onReceive: lieberto: 04:ED:33:63:9E:39
D/MainActivity: onReceive: Action Found
    onReceive: MEDION TV: 70:54:B4:19:31:65
D/MainActivity: onReceive: Action Found

但是当我在电话 2 上试用它时：它就停在这里并且没有显示任何设备：

D/MainActivity: btnDiscover: Looking for unpaired Devices
I/System.out: Discoverybool was set to: true

有人知道问题出在哪里吗？提前感谢您的每一个回答！

这是我的代码：

Android.Manifest：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.example.fernsteuerung">

    <uses-feature android:name="android.hardware.bluetooth" />

    <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" />
    <uses-permission
        android:name="android.permission.BLUETOOTH_PRIVILEGED"
        tools:ignore="ProtectedPermissions" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="NameOfApp"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"

        >
        <activity android:name=".HistoryActivity" android:screenOrientation="portrait" />
        <activity android:name=".TerminalActivity" android:screenOrientation="portrait" />
        <activity android:name=".RemoteControl" android:screenOrientation="portrait"/>
        <activity android:name=".ChooseActivity" android:screenOrientation="portrait" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

发现功能和相关的广播功能：

 public void btnDiscover(View view)
    {


        //Checken ob Bluetooth an ist
        if (mBluetoothAdapter == null)  // Wenn das Gerät keinen Bluetooth Adapter hat
        {
            Log.d(TAG,"enableDisableBT: Does not have Bluetooth capabilities");
        }
        if(!(mBluetoothAdapter.isEnabled())) // Wenn Bluetooth ausgeschaltet ist
        {
            Log.d(TAG,"enableDisableBT: enabling BT.");
            Intent enableBTIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivity(enableBTIntent);

            IntentFilter BTIntent = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
            registerReceiver(mBroadcastReceiver1, BTIntent);
        }


        Log.d(TAG,"btnDiscover: Looking for unpaired Devices");


        if(mBluetoothAdapter.isDiscovering())
        {
            mBluetoothAdapter.cancelDiscovery();
            Log.d(TAG,"btnDiscover:Cancelling discovery.");
            //Checkt ob die Berechtigungen im Manifest für BT vorliegen
            checkBTPermissions();


            //start discovery again
           mBluetoothAdapter.startDiscovery();
            //scann(mBluetoothAdapter,30);
            //System.out.println("scann1 was aufgerufen");
            IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
            registerReceiver(mBroadcastReceiver3,discoverDevicesIntent);


        }

        if(!(mBluetoothAdapter.isDiscovering()))
        {
            //another check
            checkBTPermissions();

            mBluetoothAdapter.startDiscovery();
            //scann(mBluetoothAdapter,30);
            //System.out.println("scann2 wurde aufgerufen");
            IntentFilter discoverDevicesIntent = new IntentFilter(BluetoothDevice.ACTION_FOUND);
            registerReceiver(mBroadcastReceiver3,discoverDevicesIntent);
        }
        discoverybool = true;
        System.out.println("Discoverybool was set to: " + discoverybool);


    }

    @RequiresApi(api = Build.VERSION_CODES.M)
    private void checkBTPermissions() {
        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.");
        }
    }

相关广播：



    // Create a BroadcastReceiver for ACTION_FOUND
    private final BroadcastReceiver mBroadcastReceiver1 = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            // When discovery finds a device
            if (action.equals(mBluetoothAdapter.ACTION_STATE_CHANGED)) {
                final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, mBluetoothAdapter.ERROR);

                switch(state){
                    case BluetoothAdapter.STATE_OFF:
                        Log.d(TAG, "onReceive: STATE OFF");
                        break;
                    case BluetoothAdapter.STATE_TURNING_OFF:
                        Log.d(TAG, "mBroadcastReceiver1: STATE TURNING OFF");
                        break;
                    case BluetoothAdapter.STATE_ON:
                        Log.d(TAG, "mBroadcastReceiver1: STATE ON");
                        break;
                    case BluetoothAdapter.STATE_TURNING_ON:
                        Log.d(TAG, "mBroadcastReceiver1: STATE TURNING ON");
                        break;
                }
            }
        }
    };








    //Bluetooth Broadcoast receiver für den Button
    private final BroadcastReceiver mBroadcastReceiver2 = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            // When discovery finds a device
            if (action.equals(BluetoothAdapter.ACTION_SCAN_MODE_CHANGED)) {

                int mode = intent.getIntExtra(BluetoothAdapter.EXTRA_SCAN_MODE,BluetoothAdapter.ERROR);

                switch(mode)
                {
                    //Wenn das Device in Discoverable Mode ist
                    case BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE:
                        Log.d(TAG,"mBroadcastReceiver2: Discoverability Enabled.");
                        break;

                    //Wenn das Device nicht im discoverable mode ist:
                    case BluetoothAdapter.SCAN_MODE_CONNECTABLE:
                        Log.d(TAG,"mBroadcastReceiver2: Discoverability Disabled. Able to receive connections.");
                        break;
                    case BluetoothAdapter.SCAN_MODE_NONE:
                        Log.d(TAG,"mBroadcastReceiver2: Discoverability Disabled. Not able to receive connections.");
                        break;
                    case BluetoothAdapter.STATE_CONNECTING:
                        Log.d(TAG,"mBroadcastReceiver2: Connecting...");
                        break;
                    case BluetoothAdapter.STATE_CONNECTED:
                        Log.d(TAG,"mBroadcastReceiver2:Connected.");
                        break;

                }


            }
        }
    };










    //Broadcast Receiver 3 für discover devices list

    private BroadcastReceiver mBroadcastReceiver3 = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            final String action = intent.getAction();
            Log.d(TAG,"onReceive: Action Found");

            if(action.equals(BluetoothDevice.ACTION_FOUND))
            {
                BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);




                Log.d(TAG, "onReceive: " + device.getName() + ": " + device.getAddress());

                if(device.getName() != null)
                    {
                       
                        if(device.getName().contains("HC")) {
                            if(mBTDevices.size() < 1 ) {
                                mBTDevices.add(device);
                                mDeviceListAdapter = new DeviceListAdapter(context, R.layout.device_adapter_view, mBTDevices);
                                lvNewDevices.setAdapter((mDeviceListAdapter));
                            }
                        }
                    }

            }

            /*else if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                Log.v(TAG, "Entered the Finished ");
                System.out.println("Entered the Finished");
            }

             */

        }




    };

类 DeviceListAdapter.java

package com.example.fernsteuerung;


import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.ArrayList;


public class DeviceListAdapter extends ArrayAdapter<BluetoothDevice> {

    private LayoutInflater mLayoutInflater;
    private ArrayList<BluetoothDevice> mDevices;
    private int  mViewResourceId;

    public DeviceListAdapter(Context context, int tvResourceId, ArrayList<BluetoothDevice> devices){
        super(context, tvResourceId,devices);
        this.mDevices = devices;
        mLayoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mViewResourceId = tvResourceId;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        convertView = mLayoutInflater.inflate(mViewResourceId, null);

        BluetoothDevice device = mDevices.get(position);

        if (device != null) {
            TextView deviceName = (TextView) convertView.findViewById(R.id.tvDeviceName);
            TextView deviceAdress = (TextView) convertView.findViewById(R.id.tvDeviceAddress);

            if (deviceName != null) {
                deviceName.setText(device.getName());
            }
            if (deviceAdress != null) {
                deviceAdress.setText(device.getAddress());
            }
        }

        return convertView;
    }

}

【问题讨论】：

标签： java android android-studio bluetooth android-version

【解决方案1】：

如果您正在使用 BLe 并且您正在充当 BLEClient，那么您可以更改 setMtu() 方法。正如您所说的那样，您应该在 onMtuChanged() 覆盖方法中收到确认，但有时在 Android 10 中您没有收到 onMtuChanged() 覆盖方法中的确认。因为您将 mtu 设置得太高，请尝试使用 512 mtu。

希望这将在 Android 10 中运行。

【讨论】：

我真的很抱歉，但我不明白。你是什么意思 bei setMtu 方法。我没有在我的代码中使用这种方法

【解决方案2】：

从 API 29 开始，Google 需要 LOCATION 组权限才能使用某些蓝牙功能。因此，您需要在 Android Manifest 中添加一些标签，并且不要忘记在 RUNTIME 请求这些权限。

我不记得具体需要哪个位置了，所以你可以添加以下所有 3 个，这样蓝牙功能就可以工作了。：

android.permission.ACCESS_FINE_LOCATION
android.permission.ACCESS_COARSE_LOCATION
android.permission.ACCESS_BACKGROUND_LOCATION

【讨论】：