在我的应用程序的一个要求中，我需要弹出一个包含前置摄像头预览的活动，同时我也需要打开手电筒。但是我观察到，我能够打开手电筒和后置摄像头，但不是前置摄像头和手电筒。以下是我的代码：
public class Cam extends Activity {
private static int cameraId = 0;
private Camera camera;
//Adding for camera preview
public static FrameLayout preview;
public static CameraPreview mPreview;
Context context;
ImageButton btnSwitch;
private boolean isFlashOn;
private boolean hasFlash;
Parameters params;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.e("Cam","Inside onCreate");
setContentView(R.layout.cam);
context = getApplicationContext();
btnSwitch = (ImageButton) findViewById(R.id.btnSwitch);
hasFlash = getApplicationContext().getPackageManager()
.hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
startCamera();
// displaying button image
toggleButtonImage();
btnSwitch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (isFlashOn) {
turnOffFlash();
} else {
turnOnFlash();
}
}
});
}
@Override
protected void onPause() {
super.onPause();
turnOffFlash();
Log.e("Cam","Inside onPause");
try {
if (camera != null) {
camera.release();
camera = null;
preview.removeView(mPreview);
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void onResume() {
super.onResume();
Log.e("Cam","Inside onResume");
try {
if(camera ==null) {
Log.d("Cam","in resume,camera is null");
try {
camera = android.hardware.Camera.open(cameraId); //opens front cam
// camera = Camera.open(); when I use this I can on/off the flashlight,since I am using the back camera.
mPreview = new CameraPreview(this, camera);
preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.e("Cam","Inside onDestroy");
if (camera != null) {
try {
camera.release();
camera = null;
preview.removeView(mPreview);
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void startCamera() {
Log.e("Cam","Inside doInBackground");
String msg = "";
// Do we have a camera?
try {
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
} else {
cameraId = AppFunctions.findFrontFacingCamera();//A function that returns 0 for front camera
if (cameraId < 0) {
} else {
try {
camera = Camera.open(cameraId);//opens front cam
// camera = Camera.open(); when I use this I can on/off the flashlight,since I am calling the back camera.
params = camera.getParameters();
Log.e("Cam","camera id" + cameraId);
Log.e("Cam","params" + params);
} catch (Exception e) {
e.printStackTrace();
}
try {
mPreview = new CameraPreview(getApplicationContext(), camera);
preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
} catch (Exception e) {
e.printStackTrace();
}
}
}
} catch (Exception e3) {
e3.printStackTrace();
}
}
private void turnOnFlash() {
Log.v("Cam","Inside turnOnFlash");
if (!isFlashOn) {
if (camera == null || params == null) {
Log.v("Cam","camera or param is null");
return;
}
params.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(params);
camera.startPreview();
isFlashOn = true;
// changing button/switch image
toggleButtonImage();
}
}
/*
* Turning Off flash
*/
private void turnOffFlash() {
Log.v("Cam","Inside turnOffFlash");
if (isFlashOn) {
if (camera == null || params == null) {
Log.v("Cam","camera or param is null");
return;
}
params.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(params);
camera.stopPreview();
isFlashOn = false;
// changing button/switch image
toggleButtonImage();
}
}
private void toggleButtonImage(){
if(isFlashOn){
btnSwitch.setImageResource(R.drawable.btn_switch_on);
}else{
btnSwitch.setImageResource(R.drawable.btn_switch_off);
}
}
}
清单
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.front" />
<permission android:name="android.permission.FLASHLIGHT" />
如何同时打开手电筒和前凸轮？任何帮助将不胜感激！
答案 0 :(得分：1)
手电筒
public void onToggleClicked(View view) {
PackageManager pm = context.getPackageManager();
final Parameters p = camera.getParameters();
if (isFlashSupported(pm)) {
boolean on = ((ToggleButton) view).isChecked();
if (on) {
Log.i("info", "torch is turn on!");
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
camera.startPreview();
} else {
Log.i("info", "torch is turn off!");
p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);
camera.stopPreview();
}
相机：
ImageButton ib = (ImageButton) findViewById(R.id.buttonToast);
ib.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
startActivityForResult(i, CAPTURE_IMAGE_CAPTURE_CODE);
}
});
答案 1 :(得分：1)
答案 2 :(得分：0)
以下代码检查前置摄像头的可用性：
private Camera openFrontFacingCameraGingerbread() {
int cameraCount = 0;
Camera cam = null;
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
cameraCount = Camera.getNumberOfCameras();
for (int camIdx = 0; camIdx < cameraCount; camIdx++) {
Camera.getCameraInfo(camIdx, cameraInfo);
if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
try {
cam = Camera.open(camIdx);
} catch (RuntimeException e) {
Log.e(TAG, "Camera failed to open: " + e.getLocalizedMessage());
}
}
}
return cam;
}
然后在AndroidManifest.xml文件中添加以下权限：
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" android:required="false" />
<uses-feature android:name="android.hardware.camera.front" android:required="false" />
注意：此功能在Gingerbread（2.3）和Up Android Version中可用。
我建议使用this示例中的surfaceView来实现有效的手电筒。
希望这会有所帮助：）