在清单中：
<?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>
在 MainActivity 中：
@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
}
完整的 MainActivity 代码：
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();
}
}