Android 手电筒在从其他活动返回时强制关闭

Question

我按照教程here 并设法在我的应用程序中实现了闪光灯。然而，我已经陷入困境。

闪光灯按钮在第一次加载应用程序时会产生奇迹，但是当您转到另一个活动（页面）然后返回第一个活动（页面）并尝试使用闪光灯按钮时，它会强制关闭应用程序

这是我加载应用程序的 logCat，打开和关闭手电筒导航到另一个活动，然后再次尝试使用闪光灯，然后 bam 死了

08-18 23:12:50.854: I/info(10685): torch is turn on!
08-18 23:12:51.565: D/View(10685): onTouchEvent: viewFlags: 0x18004001
08-18 23:12:51.565: D/View(10685): onTouchEvent: isFocusable: true, isFocusableInTouchMode: false, isFocused: false; focusTaken: false
08-18 23:12:51.565: I/info(10685): torch is turn off!
08-18 23:12:58.522: D/View(10685): onTouchEvent: viewFlags: 0x18004001
08-18 23:12:58.522: D/View(10685): onTouchEvent: isFocusable: true, isFocusableInTouchMode: false, isFocused: false; focusTaken: false
08-18 23:12:58.672: D/ATRecorder(10685): com.htc.autotest.dlib.RecordEngine in loader dalvik.system.DexClassLoader@4054f238
08-18 23:12:58.682: D/WindowManagerImpl(10685): addView, new view, mViews[1]: com.android.internal.policy.impl.PhoneWindow$DecorView@40545f00
08-18 23:12:58.912: D/Camera-JNI(10685): native_release: context=0x34cec0 camera=0x34ce78
08-18 23:13:00.844: W/KeyCharacterMap(10685): Can't open keycharmap file
08-18 23:13:00.854: W/KeyCharacterMap(10685): Error loading keycharmap file '/system/usr/keychars/synaptics-rmi-touchscreen.kcm.bin'. hw.keyboards.65537.devname='synaptics-rmi-touchscreen'
08-18 23:13:00.854: I/KeyCharacterMap(10685): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
08-18 23:13:01.214: D/WindowManagerImpl(10685): finishRemoveViewLocked, mViews[1]: com.android.internal.policy.impl.PhoneWindow$DecorView@40545f00
08-18 23:13:02.205: D/View(10685): onTouchEvent: viewFlags: 0x18004001
08-18 23:13:02.205: D/View(10685): onTouchEvent: isFocusable: true, isFocusableInTouchMode: false, isFocused: false; focusTaken: false
08-18 23:13:02.205: I/info(10685): torch is turn on!
08-18 23:13:02.205: D/AndroidRuntime(10685): Shutting down VM
08-18 23:13:02.205: W/dalvikvm(10685): threadid=1: thread exiting with uncaught exception (group=0x4001d5a0)
08-18 23:13:02.215: E/AndroidRuntime(10685): FATAL EXCEPTION: main
08-18 23:13:02.215: E/AndroidRuntime(10685): java.lang.RuntimeException: Method called after release()
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.hardware.Camera.native_setParameters(Native Method)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.hardware.Camera.setParameters(Camera.java:958)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at com.reading.festival.ReadingFestivalGuide2012Activity$1.onClick(ReadingFestivalGuide2012Activity.java:84)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.view.View.performClick(View.java:2533)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.view.View$PerformClick.run(View.java:9320)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.os.Handler.handleCallback(Handler.java:587)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.os.Handler.dispatchMessage(Handler.java:92)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.os.Looper.loop(Looper.java:150)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at android.app.ActivityThread.main(ActivityThread.java:4385)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at java.lang.reflect.Method.invokeNative(Native Method)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at java.lang.reflect.Method.invoke(Method.java:507)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
08-18 23:13:02.215: E/AndroidRuntime(10685):    at dalvik.system.NativeStart.main(Native Method)

相机代码

private boolean isLighOn = false;

    private Camera camera;

    private Button button;

    @Override
    protected void onStop() {
        super.onStop();

        if (camera != null) {
            camera.release();
        }
    }


        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //makes full screen and takes away title bar
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        //



        setContentView(R.layout.main);

        button = (Button) findViewById(R.id.buttonFlashlight);

        Context context = this;
        PackageManager pm = context.getPackageManager();

        // if device support camera?
        if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
            Log.e("err", "Device has no camera!");
            return;
        }

        camera = Camera.open();
        final Parameters p = camera.getParameters();

        button.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                if (isLighOn) {

                    Log.i("info", "torch is turn off!");

                    p.setFlashMode(Parameters.FLASH_MODE_OFF);
                    camera.setParameters(p);
                    camera.stopPreview();
                    isLighOn = false;

                } else {

                    Log.i("info", "torch is turn on!");

                    p.setFlashMode(Parameters.FLASH_MODE_TORCH);

                    camera.setParameters(p);
                    camera.startPreview();
                    isLighOn = true;

                }

            }
        });

Answer 1

您在调用camera.release() 之后又调用了camera.setparameters()。 释放后不应调用 setparameters。