BluetoothAdapter在Android6.0/7.0+以上startDiscovery不能发现蓝牙设备问题

Bertha 。 2023-10-17 15:43 7阅读 0赞

**BluetoothAdapter在Android6.0+以上startDiscovery不能发现蓝牙设备问题**

问题的重要原因之一是Android 6.0+，Android 7.0+的权限问题引起的。在Android 4.0+上运行良好的蓝牙代码，在高版本运行异常。比如BluetoothAdapter的startDiscovery虽然启动了发现蓝牙任务，但是不能发现蓝牙设备。解决问题是针对最新高版本的Android系统增加权限申请。现在给出一个完整例子。

activity\_main.xml：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context="zhangphil.bluetooth.MainActivity">
    
        <Button
            android:id="@+id/init"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="初始化蓝牙设备" />
    
        <Button
            android:id="@+id/discovery"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="发现设备" />
    
        <Button
            android:id="@+id/enable_discovery"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="使自身可被其他蓝牙设备发现" />
    
        <ListView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/listView">
        </ListView>
    </LinearLayout>

测试的MainActivity.java：

package zhangphil.bluetooth;
    
    import android.Manifest;
    import android.app.Activity;
    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.content.pm.PackageManager;
    import android.os.Build;
    import android.os.Bundle;
    import android.util.Log;
    import android.view.View;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    
    public class MainActivity extends Activity implements View.OnClickListener {
        private final int REQUEST_ENABLE_BT = 0xa01;
        private final int PERMISSION_REQUEST_COARSE_LOCATION = 0xb01;
    
        private String TAG = "zhangphil";
    
        private ArrayAdapter<String> mAdapter;
        private BluetoothAdapter mBluetoothAdapter;
    
        // 广播接收发现蓝牙设备
        private BroadcastReceiver mReceiver = new BroadcastReceiver() {
    
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
    
                if (BluetoothAdapter.ACTION_DISCOVERY_STARTED.equals(action)) {
                    Log.d(TAG, "开始扫描...");
                }
    
                if (BluetoothDevice.ACTION_FOUND.equals(action)) {
                    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                    if (device != null) {
                        // 添加到ListView的Adapter。
                        mAdapter.add("设备名:" + device.getName() + "\n设备地址:" + device.getAddress());
                        mAdapter.notifyDataSetChanged();
                    }
                }
    
                if (BluetoothAdapter.ACTION_DISCOVERY_FINISHED.equals(action)) {
                    Log.d(TAG, "扫描结束.");
                }
            }
        };
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                if (this.checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, PERMISSION_REQUEST_COARSE_LOCATION);
                }
            }
    
    
            // 注册广播接收器。
            // 接收蓝牙发现
            IntentFilter filterFound = new IntentFilter(BluetoothDevice.ACTION_FOUND);
            registerReceiver(mReceiver, filterFound);
    
            IntentFilter filterStart = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_STARTED);
            registerReceiver(mReceiver, filterStart);
    
            IntentFilter filterFinish = new IntentFilter(BluetoothAdapter.ACTION_DISCOVERY_FINISHED);
            registerReceiver(mReceiver, filterFinish);
    
            mAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, android.R.id.text1);
            ((ListView) findViewById(R.id.listView)).setAdapter(mAdapter);
    
            findViewById(R.id.init).setOnClickListener(this);
            findViewById(R.id.discovery).setOnClickListener(this);
            findViewById(R.id.enable_discovery).setOnClickListener(this);
        }
    
        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.init:
                    init();
    
                case R.id.discovery:
                    discovery();
    
                case R.id.enable_discovery:
                    enable_discovery();
            }
        }
    
        // 初始化蓝牙设备
        private void init() {
            mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
    
            // 检查设备是否支持蓝牙设备
            if (mBluetoothAdapter == null) {
                Log.d(TAG, "设备不支持蓝牙");
    
                // 不支持蓝牙，退出。
                return;
            }
    
            // 如果用户的设备没有开启蓝牙，则弹出开启蓝牙设备的对话框，让用户开启蓝牙
            if (!mBluetoothAdapter.isEnabled()) {
                Log.d(TAG, "请求用户打开蓝牙");
    
                Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
                // 接下去，在onActivityResult回调判断
            }
        }
    
        // 启动蓝牙发现...
        private void discovery() {
            if (mBluetoothAdapter == null) {
                init();
            }
    
            mBluetoothAdapter.startDiscovery();
        }
    
        // 可选方法，非必需
        // 此方法使自身的蓝牙设备可以被其他蓝牙设备扫描到，
        // 注意时间阈值。0 - 3600 秒。
        // 通常设置时间为120秒。
        private void enable_discovery() {
            Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
    
            // 第二个参数可设置的范围是0~3600秒，在此时间区间（窗口期）内可被发现
            // 任何不在此区间的值都将被自动设置成120秒。
            discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 3600);
    
            startActivity(discoverableIntent);
        }
    
        @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
    
            if (requestCode == REQUEST_ENABLE_BT) {
                if (resultCode == RESULT_OK) {
                    Log.d(TAG, "打开蓝牙成功！");
                }
    
                if (resultCode == RESULT_CANCELED) {
                    Log.d(TAG, "放弃打开蓝牙！");
                }
    
            } else {
                Log.d(TAG, "蓝牙异常！");
            }
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
            unregisterReceiver(mReceiver);
        }
    
    
        @Override
        public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
            switch (requestCode) {
                case PERMISSION_REQUEST_COARSE_LOCATION:
                    if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
    
                    }
    
                    break;
            }
        }
    }

不要忘记增加权限：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
        <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
        <uses-permission android:name="android.permission.BLUETOOTH" />
        <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

代码运行结果：

![Center][]

以上代码运行测试环境：硬件设备是三星S7Edge，Android版本：7.0

[Center]: https://img-blog.csdn.net/20170908172308461?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaGls/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center