Android 12下用Java+Flamingo处理蓝牙/NFC进程及后台监听问题

一、定时停止蓝牙/NFC系统进程（后台每10秒执行） #

Android 12对后台任务限制严格，短间隔定时任务需使用前台服务避免被系统回收，同时需申请对应权限：

1. 权限声明（AndroidManifest.xml） #

<uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESSES" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.NFC" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" /> <!-- Android 13+ 需添加 -->

<service
    android:name=".ProcessKillService"
    android:foregroundServiceType="dataSync" />

2. 前台服务实现（ProcessKillService.java） #

import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.Service;
import android.content.Intent;
import android.os.Build;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.app.ActivityManager;
import android.content.Context;

public class ProcessKillService extends Service {
    private static final int NOTIFICATION_ID = 1001;
    private static final String CHANNEL_ID = "ProcessKillChannel";
    private Handler handler;
    private Runnable killRunnable;

    @Override
    public void onCreate() {
        super.onCreate();
        createNotificationChannel();
        startForeground(NOTIFICATION_ID, getForegroundNotification());

        handler = new Handler(Looper.getMainLooper());
        killRunnable = new Runnable() {
            @Override
            public void run() {
                killSystemProcesses();
                handler.postDelayed(this, 10000); // 每10秒执行一次
            }
        };
        handler.post(killRunnable);
    }

    private void killSystemProcesses() {
        ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
        // 停止蓝牙进程
        am.killBackgroundProcesses("com.android.bluetooth");
        // 停止NFC进程
        am.killBackgroundProcesses("com.android.nfc");
    }

    private Notification getForegroundNotification() {
        Notification.Builder builder = new Notification.Builder(this, CHANNEL_ID)
                .setContentTitle("进程监控")
                .setContentText("正在监控并停止蓝牙/NFC进程")
                .setSmallIcon(R.drawable.ic_notification);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            builder.setChannelId(CHANNEL_ID);
        }
        return builder.build();
    }

    private void createNotificationChannel() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            NotificationChannel channel = new NotificationChannel(
                    CHANNEL_ID,
                    "进程监控频道",
                    NotificationManager.IMPORTANCE_LOW
            );
            NotificationManager manager = getSystemService(NotificationManager.class);
            manager.createNotificationChannel(channel);
        }
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (handler != null && killRunnable != null) {
            handler.removeCallbacks(killRunnable);
        }
    }
}

3. 在MainActivity启动服务 #

import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 启动前台服务
        Intent serviceIntent = new Intent(this, ProcessKillService.class);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(serviceIntent);
        } else {
            startService(serviceIntent);
        }
    }
}

二、解决编译前权限缺失与布局未约束问题 #

1. 权限缺失修复 #

• 确保上述权限已在AndroidManifest.xml中声明
• 动态申请危险权限（Android 6.0+）：在MainActivity中添加权限申请逻辑

import android.Manifest;
import android.content.pm.PackageManager;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

private static final int REQUEST_PERMISSIONS = 100;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    checkAndRequestPermissions();
}

private void checkAndRequestPermissions() {
    String[] permissions = {
            Manifest.permission.KILL_BACKGROUND_PROCESSES,
            Manifest.permission.BLUETOOTH_CONNECT,
            Manifest.permission.POST_NOTIFICATIONS
    };
    boolean needRequest = false;
    for (String perm : permissions) {
        if (ContextCompat.checkSelfPermission(this, perm) != PackageManager.PERMISSION_GRANTED) {
            needRequest = true;
            break;
        }
    }
    if (needRequest) {
        ActivityCompat.requestPermissions(this, permissions, REQUEST_PERMISSIONS);
    } else {
        // 权限已授予，启动服务
        startProcessKillService();
    }
}

@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == REQUEST_PERMISSIONS) {
        boolean allGranted = true;
        for (int result : grantResults) {
            if (result != PackageManager.PERMISSION_GRANTED) {
                allGranted = false;
                break;
            }
        }
        if (allGranted) {
            startProcessKillService();
        }
    }
}

private void startProcessKillService() {
    Intent serviceIntent = new Intent(this, ProcessKillService.class);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
        startForegroundService(serviceIntent);
    } else {
        startService(serviceIntent);
    }
}

2. 布局未约束修复 #

使用ConstraintLayout确保所有视图都有明确约束，示例activity_main.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">

    <!-- 蓝牙状态日志显示控件 -->
    <TextView
        android:id="@+id/bluetooth_log_tv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="16dp"
        android:textSize="14sp"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

所有视图需通过app:layout_constraintXXX属性绑定到父布局或其他视图，避免出现"Unconstrained view"警告。

三、后台持续监听蓝牙状态与触发源记录 #

1. 蓝牙状态监听（前台服务中注册广播接收器） #

在ProcessKillService中添加蓝牙状态广播监听：

import android.bluetooth.BluetoothAdapter;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import androidx.localbroadcastmanager.content.LocalBroadcastManager;

private BroadcastReceiver bluetoothStateReceiver;
private StringBuilder logBuilder = new StringBuilder();

@Override
public void onCreate() {
    super.onCreate();
    // ... 原有代码 ...

    // 注册蓝牙状态广播接收器
    bluetoothStateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (BluetoothAdapter.ACTION_STATE_CHANGED.equals(action)) {
                int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR);
                switch (state) {
                    case BluetoothAdapter.STATE_TURNING_ON:
                        logBuilder.append("[" + System.currentTimeMillis() + "] 蓝牙正在启动\n");
                        // 尝试获取触发源
                        detectBluetoothTrigger();
                        sendLogToActivity();
                        break;
                    case BluetoothAdapter.STATE_ON:
                        logBuilder.append("[" + System.currentTimeMillis() + "] 蓝牙已启动\n");
                        sendLogToActivity();
                        break;
                    case BluetoothAdapter.STATE_TURNING_OFF:
                        logBuilder.append("[" + System.currentTimeMillis() + "] 蓝牙正在关闭\n");
                        sendLogToActivity();
                        break;
                    case BluetoothAdapter.STATE_OFF:
                        logBuilder.append("[" + System.currentTimeMillis() + "] 蓝牙已关闭\n");
                        sendLogToActivity();
                        break;
                }
            }
        }
    };
    IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
    registerReceiver(bluetoothStateReceiver, filter);
}

// 发送日志到MainActivity显示
private void sendLogToActivity() {
    Intent intent = new Intent("UPDATE_BLUETOOTH_LOG");
    intent.putExtra("LOG", logBuilder.toString());
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

@Override
public void onDestroy() {
    super.onDestroy();
    // ... 原有代码 ...
    if (bluetoothStateReceiver != null) {
        unregisterReceiver(bluetoothStateReceiver);
    }
}

2. 蓝牙触发源检测（局限性说明） #

Android没有公开API直接获取启动蓝牙的应用，普通应用可通过以下方式尝试检测：

• 读取系统日志：需READ_LOGS权限（系统签名权限，普通应用无法获取），若有系统签名可执行以下代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

private void detectBluetoothTrigger() {
    try {
        Process process = Runtime.getRuntime().exec("logcat -d -s BluetoothManagerService");
        BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
        String line;
        while ((line = reader.readLine()) != null) {
            if (line.contains("enable")) {
                // 解析日志中的包名，示例日志格式："BluetoothManagerService: enable called by com.example.app"
                int index = line.indexOf("called by ");
                if (index != -1) {
                    String packageName = line.substring(index + 10);
                    logBuilder.append("触发源：" + packageName + "\n");
                }
                break;
            }
        }
        reader.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

• 替代方案：使用UsageStatsManager获取蓝牙启动前后的活跃应用，需PACKAGE_USAGE_STATS权限（用户需手动在设置中授权）：

import android.app.usage.UsageStats;
import android.app.usage.UsageStatsManager;
import java.util.List;
import java.util.Calendar;

private void detectBluetoothTrigger() {
    UsageStatsManager usm = (UsageStatsManager) getSystemService(Context.USAGE_STATS_SERVICE);
    Calendar calendar = Calendar.getInstance();
    long endTime = calendar.getTimeInMillis();
    calendar.add(Calendar.SECOND, -30); // 检查过去30秒内的应用
    long startTime = calendar.getTimeInMillis();

    List<UsageStats> usageStatsList = usm.queryUsageStats(UsageStatsManager.INTERVAL_BEST, startTime, endTime);
    if (usageStatsList != null && !usageStatsList.isEmpty()) {
        UsageStats recentStats = usageStatsList.get(0);
        logBuilder.append("疑似触发源：" + recentStats.getPackageName() + "\n");
    }
}

3. MainActivity接收日志并显示 #

import androidx.localbroadcastmanager.content.LocalBroadcastManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.widget.TextView;

private TextView bluetoothLogTv;
private BroadcastReceiver logUpdateReceiver;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    bluetoothLogTv = findViewById(R.id.bluetooth_log_tv);

    // 注册本地广播接收器接收日志
    logUpdateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String log = intent.getStringExtra("LOG");
            bluetoothLogTv.setText(log);
        }
    };
    LocalBroadcastManager.getInstance(this).registerReceiver(logUpdateReceiver,
            new IntentFilter("UPDATE_BLUETOOTH_LOG"));

    checkAndRequestPermissions();
}

@Override
protected void onDestroy() {
    super.onDestroy();
    LocalBroadcastManager.getInstance(this).unregisterReceiver(logUpdateReceiver);
}

内容的提问来源于stack exchange，提问作者Ho Yeung - Lee-Maiva