android camera 录制15秒视频

你可以使用Android的Camera2 API来录制15秒的视频。以下是一个简单的示例代码，可以帮助你开始录制视频：

1. 在你的AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2. 在你的布局文件中添加一个SurfaceView元素用于预览视频：

<SurfaceView
    android:id="@+id/surfaceView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

3. 在你的Activity或Fragment中，获取SurfaceView并设置它的回调：

private SurfaceView surfaceView;
private SurfaceHolder surfaceHolder;

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

    surfaceView = findViewById(R.id.surfaceView);
    surfaceHolder = surfaceView.getHolder();
    surfaceHolder.addCallback(surfaceHolderCallback);
}

private SurfaceHolder.Callback surfaceHolderCallback = new SurfaceHolder.Callback() {
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // 初始化Camera
        initializeCamera();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        // 当SurfaceView尺寸发生变化时，更新Camera参数
        updateCameraParameters();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // 释放Camera资源
        releaseCamera();
    }
};

4. 初始化Camera并设置参数：

private CameraDevice camera;
private CameraCaptureSession captureSession;
private CaptureRequest.Builder previewRequestBuilder;
private Size previewSize;

private void initializeCamera() {
    CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
        // 获取后置摄像头
        String cameraId = cameraManager.getCameraIdList()[0];
        CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraId);
        StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
        previewSize = map.getOutputSizes(SurfaceTexture.class)[0];

        // 打开Camera
        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED) {
            cameraManager.openCamera(cameraId, cameraStateCallback, null);
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private CameraDevice.StateCallback cameraStateCallback = new CameraDevice.StateCallback() {
    @Override
    public void onOpened(CameraDevice camera) {
        MainActivity.this.camera = camera;
        // 开始预览
        startPreview();
    }

    @Override
    public void onDisconnected(CameraDevice camera) {
        camera.close();
        MainActivity.this.camera = null;
    }

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

private void startPreview() {
    try {
        SurfaceTexture texture = surfaceHolder.getSurfaceTexture();
        texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
        Surface surface = new Surface(texture);

        previewRequestBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        previewRequestBuilder.addTarget(surface);

        List<Surface> surfaces = new ArrayList<>();
        surfaces.add(surface);

        camera.createCaptureSession(surfaces, captureSessionStateCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private CameraCaptureSession.StateCallback captureSessionStateCallback = new CameraCaptureSession.StateCallback() {
    @Override
    public void onConfigured(CameraCaptureSession session) {
        captureSession = session;

        try {
            previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
            previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);

            CaptureRequest previewRequest = previewRequestBuilder.build();
            captureSession.setRepeatingRequest(previewRequest, null, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onConfigureFailed(CameraCaptureSession session) {
        session.close();
        captureSession = null;
    }
};

private void updateCameraParameters() {
    if (camera == null) {
        return;
    }

    try {
        // 获取最佳预览尺寸
        CameraCharacteristics characteristics = camera.getCameraCharacteristics(camera.getId());
        StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
        Size[] supportedSizes = map.getOutputSizes(SurfaceTexture.class);
        Size optimalSize = getOptimalPreviewSize(supportedSizes, surfaceView.getWidth(), surfaceView.getHeight());

        // 更新预览尺寸
        if (!previewSize.equals(optimalSize)) {
            previewSize = optimalSize;
            updatePreview();
        }
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private void updatePreview() {
    if (camera == null) {
        return;
    }

    try {
        // 停止当前预览
        captureSession.stopRepeating();
        captureSession.abortCaptures();

        // 更新预览大小
        SurfaceTexture texture = surfaceHolder.getSurfaceTexture();
        texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());

        // 创建新的预览请求
        Surface surface = new Surface(texture);
        previewRequestBuilder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        previewRequestBuilder.addTarget(surface);

        List<Surface> surfaces = new ArrayList<>();
        surfaces.add(surface);

        camera.createCaptureSession(surfaces, captureSessionStateCallback, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

private Size getOptimalPreviewSize(Size[] sizes, int width, int height) {
    final double ASPECT_TOLERANCE = 0.1;
    double targetRatio = (double) height / width;

    if (sizes == null) {
        return null;
    }

    Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;

    int targetHeight = height;

    for (Size size : sizes) {
        double ratio = (double) size.getWidth() / size.getHeight();
        if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) {
            continue;
        }

        if (Math.abs(size.getHeight() - targetHeight) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(size.getHeight() - targetHeight);
        }
    }

    if (optimalSize == null) {
        minDiff = Double.MAX_VALUE;
        for (Size size : sizes) {
            if (Math.abs(size.getHeight() - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.getHeight() - targetHeight);
            }
        }
    }

    return optimalSize;
}

5. 在你的Activity或Fragment中实现录制视频的逻辑：

private MediaRecorder mediaRecorder;
private File outputFile;

private void startRecording() {
    try {
        // 创建输出文件
        outputFile = new File(getExternalFilesDir(null), "video.mp4");

        // 创建MediaRecorder
        mediaRecorder = new MediaRecorder();
        mediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
        mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AAC);
        mediaRecorder.setVideoSize(previewSize.getWidth(), previewSize.getHeight());
        mediaRecorder.setVideoFrameRate(30);
        mediaRecorder.setOutputFile(outputFile.getAbsolutePath());

        // 配置MediaRecorder
        mediaRecorder.prepare();
        mediaRecorder.start();

        // 录制15秒后停止
        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                stopRecording();
            }
        }, 15000);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void stopRecording() {
    if (mediaRecorder != null) {
        mediaRecorder.stop();
        mediaRecorder.release();
        mediaRecorder = null;

        // 停止预览
        if (camera != null) {
            captureSession.close();
            captureSession = null;
            camera.close();
            camera = null;
        }

        // 播放录制的视频
        Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(outputFile.getAbsolutePath()));
        intent.setDataAndType(Uri.parse(outputFile.getAbsolutePath()), "video/*");
        startActivity(intent);
    }
}

6. 最后，在你的Activity或Fragment中添加一个按钮来启动录制：

public void onRecordButtonClicked(View view) {
    startRecording();
}