没有预览和用户交互的情况下拍照是可能的吗？

在没有预览和用户交互的情况下拍照是可能的。下面是一个使用Android Camera2 API拍照的示例代码：

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
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.CaptureRequest;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.Image;
import android.media.ImageReader;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;
import android.util.Size;
import android.view.Surface;
import android.view.TextureView;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private static final int REQUEST_CAMERA_PERMISSION = 200;

    private TextureView textureView;
    private Button captureButton;

    private CameraManager cameraManager;
    private String cameraId;
    private CameraDevice cameraDevice;
    private CameraCaptureSession cameraCaptureSession;
    private CaptureRequest.Builder captureRequestBuilder;
    private Size imageDimension;
    private ImageReader imageReader;
    private File file;
    private boolean flashSupported;
    private Handler backgroundHandler;
    private HandlerThread backgroundThread;

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

        textureView = findViewById(R.id.textureView);
        captureButton = findViewById(R.id.captureButton);

        captureButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takePicture();
            }
        });

        cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        try {
            cameraId = cameraManager.getCameraIdList()[0];
            CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
            StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
            assert map != null;
            imageDimension = map.getOutputSizes(SurfaceTexture.class)[0];

            //检查相机权限
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, REQUEST_CAMERA_PERMISSION);
                return;
            }
            cameraManager.openCamera(cameraId, stateCallback, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice camera) {
            cameraDevice = camera;
            createCameraPreview();
        }

        @Override
        public void onDisconnected(@NonNull CameraDevice camera) {
            cameraDevice.close();
        }

        @Override
        public void onError(@NonNull CameraDevice camera, int error) {
            cameraDevice.close();
            cameraDevice = null;
        }
    };

    private final ImageReader.OnImageAvailableListener imageReaderListener = new ImageReader.OnImageAvailableListener() {
        @Override
        public void onImageAvailable(ImageReader reader) {
            backgroundHandler.post(new ImageSaver(reader.acquireNextImage()));
        }
    };

    private class ImageSaver implements Runnable {

        private final Image image;

        public ImageSaver(Image image) {
            this.image = image;
        }

        @Override
        public void run() {
            ByteBuffer buffer = image.getPlanes()[0].getBuffer();
            byte[] bytes = new byte[buffer.remaining()];
            buffer.get(bytes);

            FileOutputStream output = null;
            try {
                String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
                String fileName = "IMG_" + timeStamp + ".jpg";
                File directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
                file = new File(directory, fileName);
                output = new FileOutputStream(file);
                output.write(bytes);
                Toast.makeText(MainActivity.this, "保存成功 " + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                image.close();
                if (output != null) {
                    try {
                        output.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }

    private void createCameraPreview() {
        try {
            SurfaceTexture texture =