最近在对接手环的第三方SDK，功能对接基本都是设置一个回调监听，然后调用对应的SDK方法，最后在回调方法中实现我们自己的逻辑处理。对接过程中有一个设备扫描激活页面，按照开发文档也就是调用SDK的某个方法（参数里面有一个回调监听），很简单。然而，在关闭这个页面之后，回调方法却还能被调用，之后LeakCanary也报了这个页面存在内存泄漏。进入SDK中查看了一下该方法，发现传入SDK的回调监听都会被置为static，从而一直持有调用Activity的引用，导致Activity无法被释放而产生内存泄漏。为了解决这个问题，刚开始写了一个静态内部类来解决，但后面发现几乎所有传入SDK的回调监听都会被置为static，所以只好对SDK调用方法统一再进行一层封装管理。

SDK调用方法统一管理

public class ClingManager {

    private OnScanClingDeviceListener onScanClingDeviceListener;
    private Handler mHandler;

    private static class ClingManagerHolder {
        public static final ClingManager INSTANCE = new ClingManager();
    }

    private ClingManager() {
        mHandler = new Handler();
    }

    public static ClingManager getInstance() {
        return ClingManagerHolder.INSTANCE;
    }

    /**
     * 添加扫描设备监听
     * @param listener
     */
    public void addScanClingDeviceListener(OnScanClingDeviceListener listener) {
        onScanClingDeviceListener = listener;
    }

    /**
     * 移除扫描设备监听
     */
    public void removeScanClingDeviceListener() {
        onScanClingDeviceListener = null;
    }

    /**
     * 扫描设备
     */
    public void scanClingDevice() {
        ClingSdk.startScan(10 * 60 * 1000, new OnBleListener.OnScanDeviceListener() { 
            @Override
            public void onBleScanUpdated(Object o) {
                //蓝牙连接成功后，不会再扫描
                if (o == null) {
                    return;
                }
                final ArrayList<BluetoothDeviceInfo> arrayList = (ArrayList<BluetoothDeviceInfo>) o;
                if (arrayList.size() > 0 && onScanClingDeviceListener != null) {
                    mHandler.post(new Runnable() {
                        @Override
                        public void run() {
                            onScanClingDeviceListener.onScanClingDevice(arrayList);
                        }
                    });
                }
            }
        });
    }

    /**
     * 扫描设备监听
     */
    public interface OnScanClingDeviceListener {
        void onScanClingDevice(ArrayList<BluetoothDeviceInfo> clingDeviceList);
    }
}

Activity中调用

需要注意的就是要在Activity的onDestroy生命周期方法中将扫描设备回调监听移除。

public class BindActivity {

    private Handler mHandler = new Handler();

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

        initDataCallBack();
    }

    @Override
    protected void onStart() {
        super.onStart();
        registerReceiver(mBleReceiver, new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED));
        if (!BleUtil.isBleOpen()) {
            showOpenBleMsg();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        startScan();
    }

    private void showOpenBleMsg() {
        Snackbar.make(ripple, "请打开蓝牙来绑定手环/手表", Snackbar.LENGTH_INDEFINITE)
                .setAction("打开蓝牙", new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent mIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                        startActivityForResult(mIntent, REQUEST_OPEN_BLE);
                    }
                })
                .show();
    }

    private void initDataCallBack() {
        // 扫描设备回调监听
        ClingManager.getInstance().addScanClingDeviceListener(new ClingManager.OnScanClingDeviceListener() {
            @Override
            public void onScanClingDevice(ArrayList<BluetoothDeviceInfo> clingDeviceList) {
                for (BluetoothDeviceInfo clingDevice : clingDeviceList) {
                    if (TextUtils.equals(clingDevice.getmBleDevice().getName(), "PBAND 9048")) {
                        ClingSdk.stopScan();
                        ClingManager.getInstance().registerClingDevice(clingDevice);
                        break;
                    }
                }
    }

    private void startScan() {
        ClingSdk.stopScan();
        ClingSdk.setClingDeviceType(ClingSdk.CLING_DEVICE_TYPE_ALL);
        ClingManager.getInstance().scanClingDevice();
    }

    private BroadcastReceiver mBleReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            int blueState = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, 0);
            switch (blueState) {
                case BluetoothAdapter.STATE_OFF:
                    break;
                case BluetoothAdapter.STATE_TURNING_ON:
                    break;
                case BluetoothAdapter.STATE_ON:
                    mHandler.postDelayed(new Runnable() {
                        @Override
                        public void run() {
                            startScan();
                        }
                    }, 1000);
                    break;
                case BluetoothAdapter.STATE_TURNING_OFF:
                    break;
                default:
                    break;
            }
        }
    };

    @Override
    protected void onPause () {
        super.onPause();
    }

    @Override
    protected void onStop() {
        super.onStop();
        unregisterReceiver(mBleReceiver);
    }

    @Override
    protected void onDestroy () {
        super.onDestroy();
        ClingManager.getInstance().removeScanClingDeviceListener();
    }
}