android - 应用程序一旦创建就进入 onPause

Question

我有一个奇怪的问题。我正在编写一个继续拍照的应用程序。该应用程序运行良好，但是在实现 onPause 方法后它没有启动。我检查过它一旦创建就进入了 onPause。这是我的代码:

public class MyCamera extends Activity {
    private Camera mCamera;
    private CameraPreview mCameraPreview;
    private FrameLayout preview;
    /* Remaining stuff: 
        1. Implement Onpause to release camera and onResume reopen it
        2. Save timer to stop it ion onpauseoonPause()  
        3. rotate images
    */
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        mCamera = getCameraInstance();
        mCameraPreview = new CameraPreview(this, mCamera);
        mCamera.setDisplayOrientation(90);
        //FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview = (FrameLayout) findViewById(R.id.camera_preview);
        preview.addView(mCameraPreview);

        Button captureButton = (Button) findViewById(R.id.button_capture);
        captureButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            //  mCamera.takePicture(null, null, mPicture);

                // 5000ms=5s at intervals of 1000ms=1s so that means it lasts 5 seconds


                    /*new CountDownTimer(5000,1000){

                        @Override
                        public void onFinish() {

                        }

                        @Override
                        public void onTick(long millisUntilFinished) {
                            mCamera.takePicture(null, null, mPicture);

                        }

                    }.start();*/


                    Timer timer = new Timer();
                    timer.schedule(new TimerTask()
                    {
                        @Override
                        public void run()
                        {
                            mCamera.startPreview();
                            mCamera.takePicture(null, null, mPicture);
                            try {
                                Thread.sleep(500);
                            } catch(InterruptedException ex) {
                                Thread.currentThread().interrupt();
                            }
                            mCamera.startPreview();                                   
                        }
                    }, 0, 5000);

            }

        });
    }

    /**
     * Helper method to access the camera returns null if it cannot get the 
     * camera or does not exist
     * 
     * @return
     */
    private Camera getCameraInstance() {
        Camera camera = null;
        try {
            camera = Camera.open();
        } catch (Exception e) {
            // cannot get camera or does not exist
        }
        return camera;
    }

    PictureCallback mPicture = new PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            File pictureFile = getOutputMediaFile();
            if (pictureFile == null) {
                return;
            }
            try {
                //createBitmap(Bitmap source, int x, int y, int width, int height, Matrix m, boolean filter);
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {

            } catch (IOException e) {
            }
        }

    };

    private static File getOutputMediaFile() {
        File mediaStorageDir = new File(
                Environment
                        .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
                "MyCameraApp");
        if (!mediaStorageDir.exists()) {
            if (!mediaStorageDir.mkdirs()) {
                Log.d("MyCameraApp", "failed to create directory");
                return null;
            }
        }
        // Create a media file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
                .format(new Date());
        File mediaFile;
        mediaFile = new File(mediaStorageDir.getPath() + File.separator
                + "IMG_" + timeStamp + ".jpg");

        return mediaFile;
    }



    @Override
    public void onPause() {
        super.onPause();  // Always call the superclass method first
        Log.d("LifeCycle", "In the onPause() event");
        // Release the Camera because we don't need it when paused
        // and other activities might need to use it.
        preview.removeAllViews();
        if (mCamera != null) {
            mCamera.release();
            mCamera = null;
        }

    }

    /*@Override
    public void onResume() {
        super.onResume();  // Always call the superclass method first
        setContentView(R.layout.main);
        // Get the Camera instance as the activity achieves full user focus
        if (mCamera == null) {
            mCamera = getCameraInstance();
            mCameraPreview = new CameraPreview(this, mCamera);
            FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
            preview.addView(mCameraPreview);
            mCamera.startPreview();

        }
    }*/ 

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

}

这是 LogCat 窗口:

04-17 14:44:11.954: I/dalvikvm(7444): Debugger is active
04-17 14:44:12.104: I/System.out(7444): Debugger has connected
04-17 14:44:12.104: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:12.314: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:12.514: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:12.714: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:12.914: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:13.114: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:13.314: I/System.out(7444): waiting for debugger to settle...
04-17 14:44:13.514: I/System.out(7444): debugger has settled (1453)
04-17 14:44:13.784: D/dalvikvm(7444): Note: class Lcom/lge/mdm/manager/ILGMDMDevicePolicyManager$Stub; has 319 unimplemented (abstract) methods
04-17 14:44:14.274: D/LifeCycle(7444): In the onPause() event
04-17 14:44:14.364: I/Adreno-EGL(7444): <qeglDrvAPI_eglInitialize:385>: EGL 1.4 QUALCOMM build:  ()
04-17 14:44:14.364: I/Adreno-EGL(7444): OpenGL ES Shader Compiler Version: E031.24.00.02
04-17 14:44:14.364: I/Adreno-EGL(7444): Build Date: 01/20/14 Mon
04-17 14:44:14.364: I/Adreno-EGL(7444): Local Branch: PMH2-KK_3.5-RB1-AU61-554722-586267-set2
04-17 14:44:14.364: I/Adreno-EGL(7444): Remote Branch: 
04-17 14:44:14.364: I/Adreno-EGL(7444): Local Patches: 
04-17 14:44:14.364: I/Adreno-EGL(7444): Reconstruct Branch: 
04-17 14:44:14.394: D/OpenGLRenderer(7444): Enabling debug mode 0
04-17 14:44:14.494: I/ActivityManager(7444): Timeline: Activity_idle id: android.os.BinderProxy@428b55e0 time:4511859
04-17 14:44:14.504: I/ActivityManager(7444): Timeline: Activity_idle id: android.os.BinderProxy@428b55e0 time:4511861

有什么想法吗？谢谢

Answer 1

onPause():

当 Activity 进入后台但尚未(尚未)被终止时，作为 Activity 生命周期的一部分调用。 onResume() 的对应项。当 Activity B 在 Activity A 之前启动时，将在 Activity 上调用此回调。在 A 的 onPause() 返回之前不会创建 B，因此请确保不要在此处做任何冗长的事情。

可能的原因---

• 你正在以某种方式调用一些保持当前状态的其他 Activity 后台 Activity 。在不同的点检查您的代码。

• 您以某种方式自行终止了当前 Activity ，所以这是在 Activity 被标记为被杀死之前调用。