在 Android 中自动拍摄视频通常可以通过 MediaRecorder 或 CameraX 实现。以下是使用 CameraX 的方式来实现自动拍摄视频的详细代码，因为 CameraX 相对简单且适合大多数设备。
实现步骤
- 配置 CameraX 和 VideoCapture。
- 开始并自动停止录制视频。
- 保存视频文件。
准备工作
在 build.gradle 中添加依赖：
dependencies {def camerax_version = "1.2.0"implementation "androidx.camera:camera-core:$camerax_version"implementation "androidx.camera:camera-camera2:$camerax_version"implementation "androidx.camera:camera-lifecycle:$camerax_version"implementation "androidx.camera:camera-video:$camerax_version"
}
自动录制视频的 Java 代码
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;import androidx.annotation.NonNull;
import androidx.annotation.OptIn;
import androidx.appcompat.app.AppCompatActivity;
import androidx.camera.core.CameraSelector;
import androidx.camera.lifecycle.ProcessCameraProvider;
import androidx.camera.video.FileOutputOptions;
import androidx.camera.video.PendingRecording;
import androidx.camera.video.Quality;
import androidx.camera.video.Recorder;
import androidx.camera.video.VideoCapture;
import androidx.camera.video.VideoRecordEvent;
import androidx.camera.video.VideoRecording;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;import com.google.common.util.concurrent.ListenableFuture;import java.io.File;
import java.util.concurrent.ExecutionException;public class VideoCaptureActivity extends AppCompatActivity {private static final int REQUEST_CODE_PERMISSIONS = 10;private static final String[] REQUIRED_PERMISSIONS = {Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO};private VideoCapture<Recorder> videoCapture;private VideoRecording videoRecording;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 检查权限if (allPermissionsGranted()) {startCamera(); // 启动相机} else {ActivityCompat.requestPermissions(this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS);}}// 检查权限是否被授予private boolean allPermissionsGranted() {for (String permission : REQUIRED_PERMISSIONS) {if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {return false;}}return true;}// 请求权限结果的处理@Overridepublic void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {super.onRequestPermissionsResult(requestCode, permissions, grantResults);if (requestCode == REQUEST_CODE_PERMISSIONS) {if (allPermissionsGranted()) {startCamera();} else {Toast.makeText(this, "Permissions not granted by the user.", Toast.LENGTH_SHORT).show();finish();}}}// 启动CameraXprivate void startCamera() {ListenableFuture<ProcessCameraProvider> cameraProviderFuture = ProcessCameraProvider.getInstance(this);cameraProviderFuture.addListener(() -> {try {ProcessCameraProvider cameraProvider = cameraProviderFuture.get();bindVideoCapture(cameraProvider);} catch (ExecutionException | InterruptedException e) {Log.e("VideoCaptureActivity", "Error starting camera", e);}}, ContextCompat.getMainExecutor(this));}// 绑定视频捕获功能@OptIn(markerClass = androidx.camera.video.ExperimentalVideo.class)private void bindVideoCapture(@NonNull ProcessCameraProvider cameraProvider) {// 配置 Recorder 和 VideoCaptureRecorder recorder = new Recorder.Builder().setQualitySelector(QualitySelector.from(Quality.HD)).build();videoCapture = VideoCapture.withOutput(recorder);CameraSelector cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA;try {// 取消之前的绑定并重新绑定cameraProvider.unbindAll();cameraProvider.bindToLifecycle(this, cameraSelector, videoCapture);startRecording(); // 自动开始录制视频} catch (Exception e) {Log.e("VideoCaptureActivity", "Error binding video capture", e);}}// 开始录制视频private void startRecording() {File outputDir = getExternalFilesDir(null); // 获取文件保存路径File videoFile = new File(outputDir, "video_capture_" + System.currentTimeMillis() + ".mp4");// 设置文件输出选项FileOutputOptions fileOutputOptions = new FileOutputOptions.Builder(videoFile).build();// 创建录制会话PendingRecording pendingRecording = videoCapture.getOutput().prepareRecording(this, fileOutputOptions);if (ActivityCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED) {pendingRecording.withAudioEnabled(); // 启用音频录制}// 开始录制videoRecording = pendingRecording.start(ContextCompat.getMainExecutor(this), videoRecordEvent -> {if (videoRecordEvent instanceof VideoRecordEvent.Start) {Log.d("VideoCaptureActivity", "Recording started");} else if (videoRecordEvent instanceof VideoRecordEvent.Finalize) {// 录制完成后处理VideoRecordEvent.Finalize finalizeEvent = (VideoRecordEvent.Finalize) videoRecordEvent;if (!finalizeEvent.hasError()) {Log.d("VideoCaptureActivity", "Video saved successfully: " + videoFile.getAbsolutePath());Toast.makeText(this, "Video saved: " + videoFile.getAbsolutePath(), Toast.LENGTH_SHORT).show();} else {Log.e("VideoCaptureActivity", "Error saving video: " + finalizeEvent.getError());}}});// 可选：指定录制时间限制，例如 10 秒后自动停止findViewById(R.id.stopRecordingButton).postDelayed(this::stopRecording, 10000); // 10 秒后停止录制}// 停止录制视频private void stopRecording() {if (videoRecording != null) {videoRecording.stop();videoRecording = null;Log.d("VideoCaptureActivity", "Recording stopped");}}
}
代码说明
- 权限检查：代码会检查是否授予了摄像头和音频录制权限。
- 绑定 CameraX：通过
CameraX的VideoCapture功能进行视频录制，使用Recorder来配置视频质量。 - 自动开始和停止录制：代码中
startRecording()方法会自动开始录制，并设置了一个postDelayed()方法，在 10 秒后自动停止录制。可以根据需要更改时间。 - 文件保存：视频文件保存在
getExternalFilesDir()目录下，文件名包含时间戳以避免重复。
注意事项
- 权限：确保在实际运行时已授予相机和麦克风权限。
- 保存路径：视频保存路径为
getExternalFilesDir()，这是一个沙盒目录，不需要额外的文件读写权限。
这样，您就可以通过 CameraX 在 Android 应用中实现自动拍摄视频。
