camera api2拍照步骤与完整demo

以下是使用Camera API2拍照的基本步骤：

1. 获取相机设备：使用CameraManager类获取相机设备列表，并选择需要的相机设备。

CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
String cameraId = manager.getCameraIdList()[0];
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);

2. 初始化相机设备：打开相机设备，设置相机参数，并创建一个CameraCaptureSession用于捕获图像。

manager.openCamera(cameraId, new CameraDevice.StateCallback() {
    @Override
    public void onOpened(@NonNull CameraDevice camera) {
        mCameraDevice = camera;
        try {
            //设置相机参数
            mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
            mPreviewBuilder.addTarget(mPreviewSurface);
            //创建一个CameraCaptureSession用于捕获图像
            mCameraDevice.createCaptureSession(Arrays.asList(mPreviewSurface, mImageReader.getSurface()), new CameraCaptureSession.StateCallback() {
                @Override
                public void onConfigured(@NonNull CameraCaptureSession session) {
                    mCaptureSession = session;
                    //开始预览
                    mCaptureSession.setRepeatingRequest(mPreviewBuilder.build(), null, null);
                }
                @Override
                public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                    Log.e(TAG, "Failed to configure camera capture session.");
                }
            }, null);
        } catch (CameraAccessException e) {
            Log.e(TAG, "Failed to initialize camera device.", e);
        }
    }

    @Override
    public void onDisconnected(@NonNull CameraDevice camera) {
        Log.e(TAG, "Camera device unexpectedly disconnected.");
    }

    @Override
    public void onError(@NonNull CameraDevice camera, int error) {
        Log.e(TAG, "Camera device error: " + error);
    }
}, null);

3. 拍照：创建一个CaptureRequest.Builder用于设置拍照参数，然后通过CameraCaptureSession.capture()方法捕获图片。

CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
captureBuilder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
mCaptureSession.capture(captureBuilder.build(), null, null);

4. 关闭相机：拍照完成后，需要关闭相机设备和CameraCaptureSession。

mCameraDevice.close();
mCaptureSession.close();

下面是一个完整的Camera API2拍照示例代码：

public class CameraActivity extends AppCompatActivity {
    private static final String TAG = "CameraActivity";

    private TextureView mPreviewView;
    private ImageReader mImageReader;

    private CameraDevice mCameraDevice;
    private CameraCaptureSession mCaptureSession;
    private CaptureRequest.Builder mPreviewBuilder;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        mPreviewView = findViewById(R.id.preview_view);

        //创建一个ImageReader对象用于捕获拍照图片
        mImageReader = ImageReader.newInstance(1080, 1920, ImageFormat.JPEG, 1);
        mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
            @Override
            public void onImageAvailable(ImageReader reader) {
                //拍照完成后处理图片
                Image image = reader.acquireLatestImage();
                //TODO:处理图片
                image.close();
            }
        }, null);
    }

    @Override
    protected void onResume() {
        super.onResume();

        //打开相机设备
        CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        String cameraId = manager.getCameraIdList()[0];
        CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);

        try {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                return;
            }
            manager.openCamera(cameraId, new CameraDevice.StateCallback() {
                @Override
                public void onOpened(@NonNull CameraDevice camera) {
                    mCameraDevice = camera;
                    try {
                        //设置相机参数
                        mPreviewBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
                        mPreviewBuilder.addTarget(mPreviewView.getSurfaceTexture());
                        //创建一个CameraCaptureSession用于捕获图像
                        mCameraDevice.createCaptureSession(Arrays.asList(mPreviewView.getSurfaceTexture(), mImageReader.getSurface()), new CameraCaptureSession.StateCallback() {
                            @Override
                            public void onConfigured(@NonNull CameraCaptureSession session) {
                                mCaptureSession = session;
                                //开始预览
                                mCaptureSession.setRepeatingRequest(mPreviewBuilder.build(), null, null);
                            }

                            @Override
                            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                                Log.e(TAG, "Failed to configure camera capture session.");
                            }
                        }, null);
                    } catch (CameraAccessException e) {
                        Log.e(TAG, "Failed to initialize camera device.", e);
                    }
                }

                @Override
                public void onDisconnected(@NonNull CameraDevice camera) {
                    Log.e(TAG, "Camera device unexpectedly disconnected.");
                }

                @Override
                public void onError(@NonNull CameraDevice camera, int error) {
                    Log.e(TAG, "Camera device error: " + error);
                }
            }, null);
        } catch (CameraAccessException e) {
            Log.e(TAG, "Failed to open camera device.", e);
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        //关闭相机设备和CameraCaptureSession
        if (mCameraDevice != null) {
            mCameraDevice.close();
        }
        if (mCaptureSession != null) {
            mCaptureSession.close();
        }
    }
}

希望这个示例代码对你有帮助。