Android 中的 BLE 广告

我正在开发一个应用程序来在 android 中发送 BLE 广告包。我使用 AdvertiseData 和 AdverstiseSettings 类来生成广告数据包。但是当我执行 StartAdvertising 时，它总是给我一个错误代码“2”，"ADVERTISE_FAILED_TOO_MANY_ADVERTISERS", "无法启动广告，因为没有可用的广告实例。"

下面是我的 MainActivity.JAVA 代码

package rockwellcollins.blutooth_advertise;

import android.bluetooth.BluetoothAdapter;
import android.bluetooth.le.AdvertiseCallback;
import android.bluetooth.le.AdvertiseData;
import android.bluetooth.le.AdvertiseSettings;
import android.bluetooth.le.BluetoothLeAdvertiser;
import android.bluetooth.le.BluetoothLeScanner;
import android.bluetooth.le.ScanCallback;
import android.bluetooth.le.ScanResult;
import android.os.Bundle;
import android.os.ParcelUuid;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {
    private BluetoothLeScanner mBluetoothLeScanner;
    private TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        textView = (TextView) findViewById(R.id.txtv);
        mBluetoothLeScanner = BluetoothAdapter.getDefaultAdapter().getBluetoothLeScanner();

        if( !BluetoothAdapter.getDefaultAdapter().isMultipleAdvertisementSupported() ) {
            Toast.makeText(this, "Multiple advertisement not supported", Toast.LENGTH_SHORT).show();
        }
        advertise();
        BluetoothAdapter.getDefaultAdapter().getBluetoothLeScanner().startScan(scanCallback);
    }

    private void advertise() {
        BluetoothLeAdvertiser advertiser = BluetoothAdapter.getDefaultAdapter().getBluetoothLeAdvertiser();

        AdvertiseSettings settings = new AdvertiseSettings.Builder()
                .setAdvertiseMode( AdvertiseSettings.ADVERTISE_MODE_LOW_LATENCY )
                .setTxPowerLevel( AdvertiseSettings.ADVERTISE_TX_POWER_HIGH )
                .setConnectable(false)
                .build();
        Log.i("BLE","start of advertise data after settings");
        ParcelUuid pUuid = new ParcelUuid( UUID.fromString("b161c53c-0715-11e6-b512-3e1d05defe78"));

        AdvertiseData data = new AdvertiseData.Builder()
                .setIncludeDeviceName( true )
                .setIncludeTxPowerLevel(true)
                .addServiceUuid( pUuid )
                //.addServiceData( pUuid, "Data".getBytes(Charset.forName("UTF-8") ) )
                .build();
        Log.i("BLE","before callback");
        AdvertiseCallback advertisingCallback = new AdvertiseCallback() {
            @Override
            public void onStartSuccess(AdvertiseSettings settingsInEffect) {
                super.onStartSuccess(settingsInEffect);
                Log.i("BLE", "LE Advertise success.");

            }

            @Override
            public void onStartFailure(int errorCode) {
                Log.e("BLE", "Advertising onStartFailure: " + errorCode);
                super.onStartFailure(errorCode);
            }
        };

        advertiser.startAdvertising( settings, data, advertisingCallback );
        Log.i("BLE", "start advertising");
    }

    private final ScanCallback scanCallback = new ScanCallback() {
        @Override
        public void onScanResult(int callbackType, ScanResult result) {
            printScanResult(result);
        }

        @Override
        public void onBatchScanResults(List<ScanResult> results) {
            textView.append("Received " + results.size() + " batch results:\n");
            for (ScanResult r : results) {
                printScanResult(r);
            }
        }

        @Override
        public void onScanFailed(int errorCode) {
            switch (errorCode) {
                case ScanCallback.SCAN_FAILED_ALREADY_STARTED:
                    textView.append("Scan failed: already started.\n");
                    break;
                case ScanCallback.SCAN_FAILED_APPLICATION_REGISTRATION_FAILED:
                    textView.append("Scan failed: app registration failed.\n");
                    break;
                case ScanCallback.SCAN_FAILED_FEATURE_UNSUPPORTED:
                    textView.append("Scan failed: feature unsupported.\n");
                    break;
                case ScanCallback.SCAN_FAILED_INTERNAL_ERROR:
                    textView.append("Scan failed: internal error.\n");
                    break;
            }
        }

        private void printScanResult(ScanResult result) {
            String id = result.getDevice() != null ? result.getDevice().getAddress() : "unknown";
            int tx = result.getScanRecord() != null ? result.getScanRecord().getTxPowerLevel() : 0;
            textView.append("TX: " + tx + " RX: " + result.getRssi() + " from " + id+ ".\n");
        }
    };

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

Android Manifest.xml 的代码

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="rockwellcollins.blutooth_advertise">
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

您能让我知道我做错了什么以及如何解决这个错误吗？

Thanks

根据我的经验，关于 BLE 广告的 Android 设备有 4 种类型：

1. Android 5.0 之前版本的设备 - 不支持 LE 广告
2. 搭载 Android 5+ 且不支持 LE 广告和返回的设备null from 获取蓝牙LeAdvertiser() https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#getBluetoothLeAdvertiser()。这些设备返回false from isMultipleAdvertisementSupported() https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#isMultipleAdvertisementSupported()。即使蓝牙打开，他们也会这样做（见下面的注释）。
3. 搭载 Android 5+ 的设备返回蓝牙乐广告商对象，但每次广告尝试都以ADVERTISE_FAILED_TOO_MANY_ADVERTISERS错误（这就是你遇到的情况）。这些设备返回true from isMultipleAdvertisementSupported() https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#isMultipleAdvertisementSupported()正如你所看到的，这不是真的。到目前为止，我只见过此类手机中的一款：索尼 xperia z1 Compact，但如果有的话，还会有更多。
4. 支持 LE 广告的 Android 5+ 设备。那些返回true from isMultipleAdvertisementSupported() https://developer.android.com/reference/android/bluetooth/BluetoothAdapter.html#isMultipleAdvertisementSupported()但仅当蓝牙打开时。

注：在2.、3.和4.中蓝牙乐广告商仅当蓝牙打开时才返回对象。否则null返回，因此在启用蓝牙之前，您实际上不知道设备是否支持 LE 广告。

检查 nRF Connect 应用程序：禁用蓝牙，安装应用程序，打开并选择广告商选项卡或导航菜单 -> 设备信息。在显示状态之前，它会要求您打开蓝牙。