双击电源按钮时闪光灯应打开
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【中文标题】双击电源按钮时闪光灯应打开【英文标题】：Flash should turn on when double click power button 【发布时间】：2018-05-14 06:57:37 【问题描述】：我有一个应用程序，其中只有一个切换按钮。这个切换按钮的功能是当我按下它时打开闪光灯，当我再次按下它时关闭闪光灯。但我希望即使我的设备被锁定、睡眠或工作时也能发生这种情况。每当我双击电源按钮时，应用程序功能应该在服务中运行，并通过广播它应该打开闪光灯。请让我知道如何做到这一点。
【问题讨论】：
【参考方案1】：MainActivity
package com.example.salal_khan.flashlightservices;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
public class MainActivity extends AppCompatActivity
@Override
public void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
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;
startService();
public void startService()
startService(new Intent(getBaseContext(), MyService.class));
// Method to stop the service
public void stopService()
stopService(new Intent(getBaseContext(), MyService.class));
服务
package com.example.salal_khan.flashlightservices;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.os.Binder;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;
import android.widget.Toast;
/**
* Created by salal-khan on 12/1/2017.
*/
public class MyService extends Service
@Override
public int onStartCommand(Intent intent, int flags, int startId)
// Let it continue running until it is stopped.
Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
final IntentFilter filter = new
IntentFilter(Intent.ACTION_SCREEN_ON);
filter.addAction(Intent.ACTION_SCREEN_OFF);
filter.addAction(Intent.ACTION_USER_PRESENT);
final BroadcastReceiver mReceiver = new ScreenReceiver();
registerReceiver(mReceiver, filter);
return super.onStartCommand(intent, flags, startId);
@Override
public void onDestroy()
super.onDestroy();
Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
@Override
public IBinder onBind(Intent intent)
return null;
@Override
public void onCreate()
super.onCreate();
广播接收器
package com.example.salal_khan.flashlightservices;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.hardware.Camera;
import android.util.Log;
import android.hardware.Camera.Parameters;
/**
* Created by salal-khan on 12/1/2017.
*/
public class ScreenReceiver extends BroadcastReceiver
public static boolean wasScreenOn = true;
Camera camera;
boolean isON = false;
int number_of_clicks = 0;
boolean thread_started = false;
final int DELAY_BETWEEN_CLICKS_IN_MILLISECONDS = 550;
@Override
public void onReceive(final Context context, final Intent intent)
++number_of_clicks;
if (!thread_started)
new Thread(new Runnable()
@Override
public void run()
thread_started = true;
try
Thread.sleep(DELAY_BETWEEN_CLICKS_IN_MILLISECONDS);
if (number_of_clicks == 1)
else if (number_of_clicks == 2)
if (isON)
if (camera == null)
camera = Camera.open();
Parameters p = camera.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(p);
camera.stopPreview();
isON = false;
else
if (camera == null)
camera = Camera.open();
Parameters p = camera.getParameters();
p.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
camera.startPreview();
isON = true;
number_of_clicks = 0;
thread_started = false;
catch (InterruptedException e)
e.printStackTrace();
).start();
Log.e("LOB", "onReceive");
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF))
wasScreenOn = false;
else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON))
wasScreenOn = true;
else if (intent.getAction().equals(Intent.ACTION_USER_PRESENT))
Log.e("LOB", "userpresent");
Log.e("LOB", "wasScreenOn" + wasScreenOn);
清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.salal_khan.flashlightservices">
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.PREVENT_POWER_KEY" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".MyService" />
</application>
</manifest>
【讨论】：
【参考方案2】：捕获图像
package com.example.salal_khan.SecuriteCameraServices;
import android.content.BroadcastReceiver;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.net.Uri;
import android.os.Handler;
import android.os.Looper;
import android.provider.MediaStore;
import android.util.Log;
import android.hardware.Camera.Parameters;
import android.view.SurfaceView;
import android.widget.Toast;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
/**
* Created by salal-khan on 12/1/2017.
*/
public class ScreenReceiver extends BroadcastReceiver
public static boolean wasScreenOn = true;
Camera camera = null;
boolean isON = false;
int number_of_clicks = 0;
boolean thread_started = false;
final int DELAY_BETWEEN_CLICKS_IN_MILLISECONDS = 550;
Context contexts;
@Override
public void onReceive(final Context context, final Intent intent)
contexts = context;
++number_of_clicks;
final SurfaceView mview = new SurfaceView(context);
if (camera==null)
camera = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK);
if (!thread_started)
new Thread(new Runnable()
@Override
public void run()
thread_started = true;
try
Thread.sleep(DELAY_BETWEEN_CLICKS_IN_MILLISECONDS);
if (number_of_clicks == 1)
else if (number_of_clicks == 2)
if (isON)
Camera.Parameters parameters = camera.getParameters();
parameters.setPictureFormat(PixelFormat.JPEG);
camera.setParameters(parameters);
Handler h = new Handler(Looper.getMainLooper());
h.post(new Runnable()
public void run()
try
camera.setPreviewDisplay(mview.getHolder());
camera.startPreview();
camera.takePicture(null, null, photoCallback);
catch (IOException e)
// TODO Auto-generated catch block
e.printStackTrace();
);
else
Camera.Parameters parameters = camera.getParameters();
parameters.setPictureFormat(PixelFormat.JPEG);
camera.setParameters(parameters);
Handler h = new Handler(Looper.getMainLooper());
h.post(new Runnable()
public void run()
try
camera.setPreviewDisplay(mview.getHolder());
camera.startPreview();
camera.takePicture(null, null, photoCallback);
catch (IOException e)
// TODO Auto-generated catch block
e.printStackTrace();
);
number_of_clicks = 0;
thread_started = false;
catch (InterruptedException e)
e.printStackTrace();
).start();
Log.e("LOB", "onReceive");
if (intent.getAction().equals(Intent.ACTION_SCREEN_OFF))
wasScreenOn = false;
else if (intent.getAction().equals(Intent.ACTION_SCREEN_ON))
wasScreenOn = true;
else if (intent.getAction().equals(Intent.ACTION_USER_PRESENT))
Log.e("LOB", "userpresent");
Log.e("LOB", "wasScreenOn" + wasScreenOn);
Camera.PictureCallback photoCallback = new Camera.PictureCallback()
public void onPictureTaken(byte[] data, Camera camera)
Uri uriTarget = contexts.getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new ContentValues());
OutputStream imageFileOS;
try
imageFileOS = contexts.getContentResolver().openOutputStream(uriTarget);
imageFileOS.write(data);
imageFileOS.flush();
imageFileOS.close();
// Toast.makeText(contexts.getApplicationContext(), "Image saved: " + uriTarget.toString(), Toast.LENGTH_LONG).show();
catch (FileNotFoundException e)
e.printStackTrace();
catch (IOException e)
e.printStackTrace();
;
清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.salal_khan.SecuriteCameraServices">
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.PREVENT_POWER_KEY" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.CAMERA" />
<application
android:allowBackup="true"
android:name=".MyApplication"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name="com.example.salal_khan.SecuriteCameraServices.MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name="com.example.salal_khan.SecuriteCameraServices.MyService" />
</application>
</manifest>
【讨论】：
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