使用wakelock.release（）

Question

我有一个简单的闪光灯应用程序运行良好，但当用户关闭应用程序时，应用程序崩溃。我认为问题出在唤醒锁上。

当闪光灯打开时，扭锁机打开，当闪光灯关闭时，扭锁机关闭。这样可以正常工作，但只要用户按下或回家，应用程序就会崩溃。

我的日志数据：

  

10-24 09：52：45.235：E / AndroidRuntime（6614）：流程：   r1d.org.uk.flashlight，PID：6614 10-24 09：52：45.235：   E / AndroidRuntime（6614）：java.lang.RuntimeException：无法销毁   activity {r1d.org.uk.flashlight / r1d.org.uk.flashlight.MainActivity}：   java.lang.RuntimeException：WakeLock未锁定的MyWakelockTag 10-24   09：52：45.235：E / AndroidRuntime（6614）：at   android.app.ActivityThread.performDestroyActivity（ActivityThread.java:3812）

MainActivity：

public class MainActivity extends Activity {

    private ImageView lightToggle;
    private ImageButton lightSwitch;
    Camera camera = null;
    Parameters parameters;
    Boolean isOn = false;
    int lightON = R.drawable.on;
    int lightOFF = R.drawable.off;
    int switchON = R.drawable.switch_on;
    int switchOFF = R.drawable.switch_off;
    Boolean hasFlash;
    PowerManager powerManager;
    PowerManager.WakeLock wakeLock;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        AdManager ads = new AdManager(this);
        lightToggle = (ImageView) findViewById(R.id.lightOn);
        lightSwitch = (ImageButton) findViewById(R.id.lightSwitch);
        Context context = this;
        hasFlash = context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
        powerManager = (PowerManager) getSystemService(POWER_SERVICE);
        wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyWakelockTag");

        if(!hasFlash){
            ContextThemeWrapper themedContext;
            if ( Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB ) {
                themedContext = new ContextThemeWrapper( MainActivity.this, android.R.style.Theme_Holo_Light_Dialog_NoActionBar );
            }
            else {
                themedContext = new ContextThemeWrapper( MainActivity.this, android.R.style.Theme_Light_NoTitleBar );
            }
            AlertDialog.Builder builder = new AlertDialog.Builder(themedContext);
            builder.setTitle(getResources().getString(R.string.notsupported))
                    .setMessage(getResources().getString(R.string.notsupportedinfo))
                    .setIcon(android.R.drawable.ic_dialog_alert)
                    .setNegativeButton(getResources().getString(R.string.ok), new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int i) {
                            dialog.cancel();
                        }
                    });
            builder.show();
        }
        turnOn();
        lightSwitch.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(isOn){
                    turnOff();
                } else {
                    turnOn();
                }
            }
        });
    }
    private void turnOn(){
        lightToggle.setImageDrawable(getResources().getDrawable(lightON));
        lightSwitch.setImageDrawable(getResources().getDrawable(switchON));
        wakeLock.acquire();
        if(hasFlash) {
            camera = Camera.open();
            parameters = camera.getParameters();
            parameters.setFlashMode(Parameters.FLASH_MODE_TORCH); //FLASH_MODE_ON
            camera.setParameters(parameters);
        }
        isOn = true;
    }
    private void turnOff(){
        lightToggle.setImageDrawable(getResources().getDrawable(lightOFF));
        lightSwitch.setImageDrawable(getResources().getDrawable(switchOFF));
        wakeLock.release();
        if(hasFlash) {
            parameters.setFlashMode(Parameters.FLASH_MODE_OFF);
            camera.setParameters(parameters);
            camera.release();
            camera = null;
        }
        isOn = false;
    }
    @Override
    public void onDestroy() {
        turnOff();
        super.onDestroy();
    }
    @Override
    public void onPause(){
        turnOff();
        super.onPause();
    }
    @Override
    public void onResume(){
        turnOn();
        super.onResume();
    }
}

Answer 1

在onDestroy中，您试图释放已在onPause中发布的唤醒锁。这应该有效：

if (wakeLock.isHeld()) {
    wakeLock.release();
}