相机预览画面

TextureView camView;
Handler handler;
private CameraManager mCameraManager;
private String[] permission = {
        Manifest.permission.CAMERA,
        Manifest.permission.RECORD_AUDIO,
        Manifest.permission.WRITE_EXTERNAL_STORAGE,
        Manifest.permission.READ_EXTERNAL_STORAGE
};
private CameraDevice.StateCallback mStateCallback;
private CameraDevice mCameraDevice;
private CaptureRequest.Builder mPreviewCaptureRequest;
private CameraCaptureSession.StateCallback mSessionStateCallback;
private CameraCaptureSession mCameraCaptureSession;
private CameraCaptureSession.CaptureCallback mSessionCaptureCallback;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    handler = new Handler(this.getMainLooper());

    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
        return;
    }
    //动态获取权限
    if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
            != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, permission, 1);
    }
    camView = findViewById(R.id.camView);
    initTextureViewStateListener();
    initCameraDeviceStateCallback();
    initSessionStateCallback();
    initSessionCaptureCallback();
}

private void openCamera() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    String product = getProductProperty();
    int cameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;
    if (product != null && product.contains("sample_a_none")) {
        cameraId = Camera.CameraInfo.CAMERA_FACING_BACK;
    }
    Log.d(TAG, "start camera: " + cameraId);
    mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        mCameraManager.openCamera(String.valueOf(cameraId), mStateCallback, handler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void initCameraDeviceStateCallback() {
    mStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice camera) {
            mCameraDevice = camera;
            repeatPreview();
            Log.d(TAG, "onOpened: ");
        }

        @Override
        public void onDisconnected(@NonNull CameraDevice camera) {

        }

        @Override
        public void onError(@NonNull CameraDevice camera, int error) {

        }
    };
}

private void repeatPreview() {
    try {
        SurfaceTexture surfaceTexture = camView.getSurfaceTexture();
        surfaceTexture.setDefaultBufferSize(903, 493);
        Surface previewSurface = new Surface(surfaceTexture);
        mPreviewCaptureRequest = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        mPreviewCaptureRequest.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
        mPreviewCaptureRequest.addTarget(previewSurface);
        mCameraDevice.createCaptureSession(Arrays.asList(previewSurface), mSessionStateCallback, handler);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void initTextureViewStateListener() {
    camView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
            openCamera();
        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {

        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
            return false;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture surface) {

        }
    });
}

private void initSessionStateCallback() {
    mSessionStateCallback = new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(@NonNull CameraCaptureSession session) {
            mCameraCaptureSession = session;
            try {
                mCameraCaptureSession.setRepeatingRequest(mPreviewCaptureRequest.build(), mSessionCaptureCallback, handler);
                Log.d(TAG, "mSessionStateCallback onConfigured: ");
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onConfigureFailed(@NonNull CameraCaptureSession session) {

        }
    };
}

private void initSessionCaptureCallback() {
    mSessionCaptureCallback = new CameraCaptureSession.CaptureCallback() {
        @Override
        public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
            super.onCaptureStarted(session, request, timestamp, frameNumber);
            Log.d(TAG, "mSessionCaptureCallback onCaptureStarted: ");
        }

        @Override
        public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureResult partialResult) {
            super.onCaptureProgressed(session, request, partialResult);
            Log.d(TAG, "mSessionCaptureCallback onCaptureProgressed: ");
        }

        @Override
        public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
            super.onCaptureCompleted(session, request, result);
            Log.d(TAG, "mSessionCaptureCallback onCaptureCompleted: ");
        }

        @Override
        public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
            super.onCaptureFailed(session, request, failure);
            Log.d(TAG, "mSessionCaptureCallback onCaptureFailed session: " + session.getDevice().getId());
        }
    };
}

public static String getProductProperty() {
    try {
        Class cla = Class.forName("android.os.SystemProperties");
        Method getter = cla.getDeclaredMethod("get", String.class);
        String value = (String) getter.invoke(null, "ro.product.name");
        return value;
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    return "default";
}

@Override
protected void onDestroy() {
    super.onDestroy();
    if (null != mCameraDevice) {
        mCameraDevice.close();
        mCameraDevice = null;
    }
}