onConfigurationChanged never gets called

Question

In the Manifest:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.app"
    android:versionCode="1"
    android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="10"
    android:targetSdkVersion="17" />

<uses-feature android:name="android.hardware.camera" />
<uses-feature
    android:name="android.hardware.camera.front"
    android:required="false" />

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.app.MainActivity"
        android:configChanges="keyboardHidden|orientation|screenSize"
        android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

In the MainActivity:

@Override
public void onConfigurationChanged(Configuration newConfig) {
    // TODO Auto-generated method stub
    super.onConfigurationChanged(newConfig);
    Toast.makeText(MainActivity.this,
            "newConfig.orientation = " + newConfig.orientation,
            Toast.LENGTH_LONG).show();
            //The above Toast never appears
}

Complete MainActivty Code:

public class MainActivity extends Activity {
    private SurfaceView preview = null;
    private SurfaceHolder previewHolder = null;
    private Camera camera = null;
    private boolean inPreview = false;
    private boolean cameraConfigured = false;

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

    preview = (SurfaceView) findViewById(R.id.preview);
    previewHolder = preview.getHolder();
    previewHolder.addCallback(surfaceCallback);
    previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

@Override
public void onResume() {
    super.onResume();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
        Camera.CameraInfo info = new Camera.CameraInfo();

        for (int i = 0; i < Camera.getNumberOfCameras(); i++) {
            Camera.getCameraInfo(i, info);

            if (info.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {
                camera = Camera.open(i);
            }
        }
    }

    if (camera == null) {
        camera = Camera.open();
    }
    // camera.setDisplayOrientation(90);
    startPreview();
}

@Override
public void onPause() {
    if (inPreview) {
        camera.stopPreview();
    }

    camera.release();
    camera = null;
    inPreview = false;

    super.onPause();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    new MenuInflater(this).inflate(R.menu.activity_main, menu);

    return (super.onCreateOptionsMenu(menu));
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == R.id.camera) {
        if (inPreview) {
            camera.takePicture(null, null, photoCallback);
            inPreview = false;
        }
    }

    return (super.onOptionsItemSelected(item));
}

private Camera.Size getBestPreviewSize(int width, int height,
        Camera.Parameters parameters) {
    Camera.Size result = null;

    for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
        if (size.width <= width && size.height <= height) {
            if (result == null) {
                result = size;
            } else {
                int resultArea = result.width * result.height;
                int newArea = size.width * size.height;

                if (newArea > resultArea) {
                    result = size;
                }
            }
        }
    }
    return (result);
}

private Camera.Size getSmallestPictureSize(Camera.Parameters parameters) {
    Camera.Size result = null;

    for (Camera.Size size : parameters.getSupportedPictureSizes()) {
        if (result == null) {
            result = size;
        } else {
            int resultArea = result.width * result.height;
            int newArea = size.width * size.height;
            if (newArea < resultArea) {
                result = size;
            }
        }
    }
    return (result);
}

private void initPreview(int width, int height) {
    if (camera != null && previewHolder.getSurface() != null) {
        try {
            camera.setPreviewDisplay(previewHolder);
        } catch (Throwable t) {
        }

        if (!cameraConfigured) {
            Camera.Parameters parameters = camera.getParameters();
            Camera.Size size = getBestPreviewSize(width, height, parameters);
            Camera.Size pictureSize = getSmallestPictureSize(parameters);

            if (size != null && pictureSize != null) {
                parameters.setPreviewSize(size.width, size.height);
                parameters.setPictureSize(pictureSize.width,
                        pictureSize.height);
                parameters.setPictureFormat(ImageFormat.JPEG);
                camera.setParameters(parameters);
                cameraConfigured = true;
            }
        }
    }
}

private void startPreview() {
    if (cameraConfigured && camera != null) {
        camera.startPreview();
        inPreview = true;
    }
}

SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
    public void surfaceCreated(SurfaceHolder holder) {
        // no-op -- wait until surfaceChanged()
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        initPreview(width, height);
        startPreview();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // no-op
    }
};

Camera.PictureCallback photoCallback = new Camera.PictureCallback() {
    public void onPictureTaken(byte[] data, Camera camera) {
        new SavePhotoTask().execute(data);
        camera.startPreview();
        inPreview = true;
    }
};

class SavePhotoTask extends AsyncTask<byte[], String, String> {
    @Override
    protected String doInBackground(byte[]... jpeg) {
        File photo = new File(Environment.getExternalStorageDirectory(),
                "photo.jpg");
        if (photo.exists()) {
            photo.delete();
        }
        try {
            FileOutputStream fos = new FileOutputStream(photo.getPath());

            fos.write(jpeg[0]);
            fos.close();
        } catch (java.io.IOException e) {
        }
        return (null);
    }
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    // TODO Auto-generated method stub
    super.onConfigurationChanged(newConfig);
    Toast.makeText(MainActivity.this,
            "newConfig.orientation = " + newConfig.orientation,
            Toast.LENGTH_LONG).show();
}

}

Answer 1

这是因为您的设备上禁用了自动旋转：D：D