要在Android Camera2中减少视频块/片段之间的延迟，可以使用预览回调和视频录制回调之间的双缓冲机制。以下是一个示例代码，演示如何实现此功能：

import android.Manifest;
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.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.SurfaceHolder;
import android.view.SurfaceView;
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.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "Camera2VideoDelay";
    private static final int REQUEST_CAMERA_PERMISSION_RESULT = 0;
    private static final int REQUEST_WRITE_EXTERNAL_STORAGE_PERMISSION_RESULT = 1;

    private Button mRecordButton;
    private SurfaceView mSurfaceView;
    private SurfaceHolder mSurfaceHolder;
    private CameraManager mCameraManager;
    private CameraDevice mCameraDevice;
    private String mCameraId;
    private Size mPreviewSize;
    private CaptureRequest.Builder mCaptureRequestBuilder;
    private CameraCaptureSession mPreviewCaptureSession;
    private HandlerThread mBackgroundHandlerThread;
    private Handler mBackgroundHandler;
    private File mVideoFolder;
    private String mVideoFileName;
    private ImageReader mImageReader;
    private boolean mIsRecording = false;

    private final CameraDevice.StateCallback mCameraDeviceStateCallback = new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice cameraDevice) {
            mCameraDevice = cameraDevice;
            startPreview();
        }

        @Override
        public void onDisconnected(@NonNull CameraDevice cameraDevice) {
            cameraDevice.close();
            mCameraDevice = null;
        }

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

    private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
        @Override
        public void onImageAvailable(ImageReader imageReader) {
            mBackgroundHandler.post(new ImageSaver(imageReader.acquireLatestImage()));
        }
    };

    private final CameraCaptureSession.StateCallback mPreviewCaptureSessionStateCallback = new CameraCaptureSession.StateCallback() {
        @Override
        public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
            mPreviewCaptureSession = cameraCaptureSession;
            try {
                mPreviewCaptureSession.setRepeatingRequest(mCaptureRequestBuilder.build(), null, mBackgroundHandler);
            } catch (CameraAccessException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
            Toast.makeText(MainActivity.this, "Unable to setup camera preview", Toast.LENGTH_SHORT).show();
        }
    };

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

        mSurfaceView = findViewById(R.id.surfaceView);
        mRecordButton = findViewById(R.id.recordButton);

        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder surfaceHolder) {
                setupCamera();
            }

            @Override
            public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {

            }

            @Override
            public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
                closeCamera();
            }
        });

        mRecordButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (mIsRecording) {
                    mIsRecording = false;
                    mRecordButton.setText("Record");
                } else {
                    checkWriteStoragePermission();
                }
            }
        });

        createVideoFolder();
    }

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

        startBackgroundThread();

        if (mSurfaceHolder.getSurface() != null) {