Android 5，camera2只使用闪光灯

我需要只使用带有API camera2（Android 5，API级别21）的闪存，就像火炬应用程序一样。 但我发现的所有示例都需要在视图中显示摄像机流

Answer 1

https://github.com/pinguo-yuyidong/Camera2/blob/master/app/src/main/java/us/yydcdut/androidltest/otheractivity/FlashActivity.java
在这里，您不需要预览来打开闪光灯。

Answer 2

只需使用以下课程即可在Android L中打开/关闭FlashLight，

public class FlashLightUtilForL { private CameraCaptureSession mSession; private CaptureRequest.Builder mBuilder; private CameraDevice mCameraDevice; private CameraManager mCameraManager; public FlashLightUtilForL(Context context) { try { mCameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE); //here to judge if flash is available CameraCharacteristics cameraCharacteristics = mCameraManager.getCameraCharacteristics("0"); boolean flashAvailable = cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE); if (flashAvailable) { mCameraManager.openCamera("0", new MyCameraDeviceStateCallback(), null); } else { //todo: throw Exception } //mCameraManager.openCamera("0", new MyCameraDeviceStateCallback(), null); } catch (Exception e) { e.printStackTrace(); } } class MyCameraDeviceStateCallback extends CameraDevice.StateCallback { @Override public void onOpened(CameraDevice camera) { mCameraDevice = camera; //get builder try { mBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_MANUAL); //flash on, default is on mBuilder.set(CaptureRequest.CONTROL_AE_MODE, CameraMetadata.CONTROL_AF_MODE_AUTO); mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH); List list = new ArrayList(); SurfaceTexture mSurfaceTexture = new SurfaceTexture(1); Size size = getSmallestSize(mCameraDevice.getId()); mSurfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight()); Surface mSurface = new Surface(mSurfaceTexture); list.add(mSurface); mBuilder.addTarget(mSurface); camera.createCaptureSession(list, new MyCameraCaptureSessionStateCallback(), null); } catch (CameraAccessException e) { e.printStackTrace(); } } @Override public void onDisconnected(CameraDevice camera) { } @Override public void onError(CameraDevice camera, int error) { } } private Size getSmallestSize(String cameraId) throws CameraAccessException { Size[] outputSizes = mCameraManager.getCameraCharacteristics(cameraId) .get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP) .getOutputSizes(SurfaceTexture.class); if (outputSizes == null || outputSizes.length == 0) { throw new IllegalStateException( "Camera " + cameraId + "doesn't support any outputSize."); } Size chosen = outputSizes[0]; for (Size s : outputSizes) { if (chosen.getWidth() >= s.getWidth() && chosen.getHeight() >= s.getHeight()) { chosen = s; } } return chosen; } /** * session callback */ class MyCameraCaptureSessionStateCallback extends CameraCaptureSession.StateCallback { @Override public void onConfigured(CameraCaptureSession session) { mSession = session; try { mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (CameraAccessException e) { e.printStackTrace(); } } @Override public void onConfigureFailed(CameraCaptureSession session) { } } public void turnOnFlashLight() { try { mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH); mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (Exception e) { e.printStackTrace(); } } public void turnOffFlashLight() { try { mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_OFF); mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (Exception e) { e.printStackTrace(); } } private void close() { if (mCameraDevice == null || mSession == null) { return; } mSession.close(); mCameraDevice.close(); mCameraDevice = null; mSession = null; } } 

Answer 3

这是完整的演示检查。

 package com.camera2; import android.content.Context; import android.graphics.SurfaceTexture; import android.hardware.camera2.CameraAccessException; import android.hardware.camera2.CameraCaptureSession; import android.hardware.camera2.CameraCharacteristics; import android.hardware.camera2.CameraDevice; import android.hardware.camera2.CameraManager; import android.hardware.camera2.CameraMetadata; import android.hardware.camera2.CaptureRequest; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.util.Size; import android.view.Surface; import android.view.View; import android.widget.Button; import java.util.ArrayList; import java.util.List; public class MainActivity extends AppCompatActivity { private CameraManager cameraManager; private CameraCharacteristics cameraCharacteristics; private CameraDevice mCameraDevice; private CameraCaptureSession mSession; private CaptureRequest.Builder mBuilder; private Button on; private Button off; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); on = (Button) findViewById(R.id.on); off = (Button) findViewById(R.id.off); initCamera(); } public void click(View v) { switch (v.getId()) { case R.id.on: try { turnOnFlashLight(); } catch (Exception e) { e.printStackTrace(); } break; case R.id.off: turnOffFlashLight(); break; } } private void initCamera() { cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try { String[] id = cameraManager.getCameraIdList(); if (id != null && id.length > 0) { cameraCharacteristics = cameraManager.getCameraCharacteristics(id[0]); boolean isFlash = cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE); if (isFlash) { cameraManager.openCamera(id[0], new MyCameraDeviceStateCallback(), null); } } } catch (CameraAccessException e) { e.printStackTrace(); } } class MyCameraDeviceStateCallback extends CameraDevice.StateCallback { @Override public void onOpened(CameraDevice camera) { mCameraDevice = camera; // get builder try { mBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); List list = new ArrayList(); SurfaceTexture mSurfaceTexture = new SurfaceTexture(1); Size size = getSmallestSize(mCameraDevice.getId()); mSurfaceTexture.setDefaultBufferSize(size.getWidth(), size.getHeight()); Surface mSurface = new Surface(mSurfaceTexture); list.add(mSurface); mBuilder.addTarget(mSurface); camera.createCaptureSession(list, new MyCameraCaptureSessionStateCallback(), null); } catch (CameraAccessException e) { e.printStackTrace(); } } @Override public void onDisconnected(CameraDevice camera) { } @Override public void onError(CameraDevice camera, int error) { } } private Size getSmallestSize(String cameraId) throws CameraAccessException { Size[] outputSizes = cameraManager.getCameraCharacteristics(cameraId).get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP).getOutputSizes(SurfaceTexture.class); if (outputSizes == null || outputSizes.length == 0) { throw new IllegalStateException("Camera " + cameraId + "doesn't support any outputSize."); } Size chosen = outputSizes[0]; for (Size s : outputSizes) { if (chosen.getWidth() >= s.getWidth() && chosen.getHeight() >= s.getHeight()) { chosen = s; } } return chosen; } class MyCameraCaptureSessionStateCallback extends CameraCaptureSession.StateCallback { @Override public void onConfigured(CameraCaptureSession session) { mSession = session; try { mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (CameraAccessException e) { e.printStackTrace(); } } @Override public void onConfigureFailed(CameraCaptureSession session) { } } public void turnOnFlashLight() { try { mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_TORCH); mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (Exception e) { e.printStackTrace(); } } public void turnOffFlashLight() { try { mBuilder.set(CaptureRequest.FLASH_MODE, CameraMetadata.FLASH_MODE_OFF); mSession.setRepeatingRequest(mBuilder.build(), null, null); } catch (Exception e) { e.printStackTrace(); } } private void close() { if (mCameraDevice == null || mSession == null) { return; } mSession.close(); mCameraDevice.close(); mCameraDevice = null; mSession = null; } } 

XML

表现

使用close（）关闭相机设置

Answer 4

嗯，这对我很有用：

 public class MainActivity extends AppCompatActivity { ToggleButton button; boolean flashLightStatus = true; boolean deviceHasCameraFlash = getPackageManager() .hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button= (ToggleButton) findViewById(R.id.button); FlashLightOn();//When app opens, turn it on. button.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if(deviceHasCameraFlash){ if(flashLightStatus){//when light on FlashLightOff();//we should off } else //when light off FlashLightOn();//we should on } else Toast.makeText(MainActivity.this, "No flash available on your device.", Toast.LENGTH_SHORT).show(); } }); } private void FlashLightOn() { CameraManager camManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try{ String cameraId = camManager.getCameraIdList()[0]; // Usually front camera is at 0 position. camManager.setTorchMode(cameraId, true); flashLightStatus=true; } catch (Exception e){ } } private void FlashLightOff() { CameraManager camManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try{ String cameraId = camManager.getCameraIdList()[0]; // Usually front camera is at 0 position. camManager.setTorchMode(cameraId, false); flashLightStatus=false; } catch (Exception e){ } } }