android.hardware.camera2使用指南

API 21中将原来的camera API弃用转而推荐使用新增的camera2 API，这是一个大的动作，因为新API换了架构，让开发者用起来更难了。  先来看看camera2包架构示意图：    这里引用了管道的概念将安卓设备和摄像头之间联通起来，系统向摄像头发送Capture请求，而摄像头会返回CameraMetadata。这一切建立在一个叫作CameraCaptureSession的会话中。

下面是camera2包中的主要类：    其中CameraManager是那个站在高处统管所有摄像投设备（CameraDevice）的管理者，而每个CameraDevice自己会负责建立CameraCaptureSession以及建立CaptureRequest。CameraCharacteristics是CameraDevice的属性描述类，非要做个对比的话，那么它与原来的CameraInfo有相似性。  类图中有着三个重要的callback，虽然这增加了阅读代码的难度，但是你必须要习惯，因为这是新包的风格。其中CameraCaptureSession.CaptureCallback将处理预览和拍照图片的工作，需要重点对待。

这些类是如何相互配合的？下面是简单的流程图。 

我是用SurfaceView作为显示对象（当然还可以TextureView去显示，详见参考中的项目）  核心代码如下：

mCameraManager = (CameraManager) this.getSystemService(Context.CAMERA_SERVICE); mSurfaceView = (SurfaceView)findViewById(R.id.surfaceview); mSurfaceHolder = mSurfaceView.getHolder(); mSurfaceHolder.addCallback(new SurfaceHolder.Callback() { @Override public void surfaceCreated(SurfaceHolder holder) { initCameraAndPreview(); } }); 123456789 123456789 private void initCameraAndPreview() { Log.d("linc","init camera and preview"); HandlerThread handlerThread = new HandlerThread("Camera2"); handlerThread.start(); mHandler = new Handler(handlerThread.getLooper()); try { mCameraId = ""+CameraCharacteristics.LENS_FACING_FRONT; mImageReader = ImageReader.newInstance(mSurfaceView.getWidth(), mSurfaceView.getHeight(), ImageFormat.JPEG,/*maxImages*/7); mImageReader.setOnImageAvailableListener(mOnImageAvailableListener, mHandler); mCameraManager.openCamera(mCameraId, DeviceStateCallback, mHandler); } catch (CameraAccessException e) { Log.e("linc", "open camera failed." + e.getMessage()); } } 12345678910111213141516 12345678910111213141516 private CameraDevice.StateCallback DeviceStateCallback = new CameraDevice.StateCallback() { @Override public void onOpened(CameraDevice camera) { Log.d("linc","DeviceStateCallback:camera was opend."); mCameraOpenCloseLock.release(); mCameraDevice = camera; try { createCameraCaptureSession(); } catch (CameraAccessException e) { e.printStackTrace(); } } }; 1234567891011121314 1234567891011121314 private void createCameraCaptureSession() throws CameraAccessException { Log.d("linc","createCameraCaptureSession"); mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); mPreviewBuilder.addTarget(mSurfaceHolder.getSurface()); mState = STATE_PREVIEW; mCameraDevice.createCaptureSession( Arrays.asList(mSurfaceHolder.getSurface(), mImageReader.getSurface()), mSessionPreviewStateCallback, mHandler); } 12345678910 12345678910 private CameraCaptureSession.StateCallback mSessionPreviewStateCallback = new CameraCaptureSession.StateCallback() { @Override public void onConfigured(CameraCaptureSession session) { Log.d("linc","mSessionPreviewStateCallback onConfigured"); mSession = session; try { mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); mPreviewBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); session.setRepeatingRequest(mPreviewBuilder.build(), mSessionCaptureCallback, mHandler); } catch (CameraAccessException e) { e.printStackTrace(); Log.e("linc","set preview builder failed."+e.getMessage()); } } }; 12345678910111213141516171819 12345678910111213141516171819 private CameraCaptureSession.CaptureCallback mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() { @Override public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request, TotalCaptureResult result) { // Log.d("linc","mSessionCaptureCallback, onCaptureCompleted"); mSession = session; checkState(result); } @Override public void onCaptureProgressed(CameraCaptureSession session, CaptureRequest request, CaptureResult partialResult) { Log.d("linc","mSessionCaptureCallback, onCaptureProgressed"); mSession = session; checkState(partialResult); } private void checkState(CaptureResult result) { switch (mState) { case STATE_PREVIEW: // NOTHING break; case STATE_WAITING_CAPTURE: int afState = result.get(CaptureResult.CONTROL_AF_STATE); if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState || CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState || CaptureResult.CONTROL_AF_STATE_PASSIVE_FOCUSED == afState || CaptureResult.CONTROL_AF_STATE_PASSIVE_UNFOCUSED == afState) { //do something like save picture } break; } } }; 1234567891011121314151617181920212223242526272829303132333435363738 1234567891011121314151617181920212223242526272829303132333435363738

按下capture按钮：

public void onCapture(View view) { try { Log.i("linc", "take picture"); mState = STATE_WAITING_CAPTURE; mSession.setRepeatingRequest(mPreviewBuilder.build(), mSessionCaptureCallback, mHandler); } catch (CameraAccessException e) { e.printStackTrace(); } } 123456789 123456789

测试用genemotion模拟器，直接调用笔记本的摄像头。  配置图如下：    demo界面如下图： 

源码：  请参考github中的两个demo项目：  https://github.com/pinguo-yuyidong/Camera2  https://github.com/googlesamples/android-Camera2Basic

转载：http://blog.csdn.net/lincyang/article/details/45951225