android调用系统相机自动录像

在 Android 应用程序中调用系统相机自动录像，需要使用 Camera2 API 和 MediaRecorder 类。下面是一个简单的示例代码：

1. 在你的应用程序中声明一个 SurfaceView：

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

2. 在你的 Activity 中，定义 Camera2 API 和 MediaRecorder 类的成员变量：

private CameraManager cameraManager;
private String cameraId;
private CameraDevice cameraDevice;
private CameraCaptureSession captureSession;
private SurfaceView surfaceView;
private MediaRecorder mediaRecorder;

3. 在 onCreate() 方法中初始化成员变量：

surfaceView = findViewById(R.id.surface_view);
mediaRecorder = new MediaRecorder();
cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
cameraId = cameraManager.getCameraIdList()[0];

4. 在 onStart() 方法中打开相机和预览：

@Override
protected void onStart() {
    super.onStart();
    openCamera();
}

private void openCamera() {
    try {
        cameraManager.openCamera(cameraId, new CameraDevice.StateCallback() {
            @Override
            public void onOpened(@NonNull CameraDevice camera) {
                cameraDevice = camera;
                startPreview();
            }

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

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

private void startPreview() {
    try {
        Surface surface = surfaceView.getHolder().getSurface();
        CaptureRequest.Builder builder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
        builder.addTarget(surface);
        cameraDevice.createCaptureSession(Collections.singletonList(surface), new CameraCaptureSession.StateCallback() {
            @Override
            public void onConfigured(@NonNull CameraCaptureSession session) {
                captureSession = session;
                try {
                    captureSession.setRepeatingRequest(builder.build(), null, null);
                } catch (CameraAccessException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                captureSession = null;
            }
        }, null);
    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

5. 在一个按钮的点击事件中，开始录像：

Button btnRecord = findViewById(R.id.btn_record);
btnRecord.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        startRecording();
    }
});

private void startRecording() {
    try {
        mediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
        mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
        mediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
        mediaRecorder.setOutputFile(getOutputFile().getPath());
        mediaRecorder.setVideoSize(640, 480);
        mediaRecorder.setVideoFrameRate(30);
        mediaRecorder.prepare();
        Surface surface = mediaRecorder.getSurface();
        CaptureRequest.Builder builder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
        builder.addTarget(surface);
        List<Surface> surfaces = Arrays.asList(surface, surfaceView.getHolder().getSurface());
        cameraDevice.createCaptureSession(surfaces, new CameraCaptureSession.StateCallback() {
            @Override
            public void onConfigured(@NonNull CameraCaptureSession session) {
                captureSession = session;
                try {
                    captureSession.setRepeatingRequest(builder.build(), null, null);
                    mediaRecorder.start();
                } catch (CameraAccessException | IllegalStateException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
                captureSession = null;
            }
        }, null);
    } catch (IOException | CameraAccessException e) {
        e.printStackTrace();
    }
}

6. 在 onStop() 方法中停止录像和相机预览：

@Override
protected void onStop() {
    super.onStop();
    stopRecording();
    stopPreview();
}

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

private void stopPreview() {
    if (captureSession != null) {
        captureSession.close();
        captureSession = null;
    }
    if (cameraDevice != null) {
        cameraDevice.close();
        cameraDevice = null;
    }
}

以上代码仅作为一个简单示例，实际应用中可能需要更多的配置和错误处理。请注意，自动录像可能会违反用户隐私，应慎重使用。