Android动态人脸检测的示例代码（脸数可调）

public class FindFaceView extends SurfaceView implements SurfaceHolder.Callback {  private SurfaceHolder holder;  private int mWidth;  private int mHeight;  private float eyesDistance;  public FindFaceView(Context context, AttributeSet attrs) {    super(context, attrs);    holder = getHolder();    holder.addCallback(this);    holder.setFormat(PixelFormat.TRANSPARENT);    this.setZOrderOnTop(true);  }  @Override  public void surfaceChanged(SurfaceHolder holder, int format, int width,                int height) {    mWidth = width;    mHeight = height;  }  @Override  public void surfaceCreated(SurfaceHolder holder) {  }  @Override  public void surfaceDestroyed(SurfaceHolder holder) {  }  public void drawRect(FaceDetector.Face[] faces, int numberOfFaceDetected) {    Canvas canvas = holder.lockCanvas();    if (canvas != null) {      Paint clipPaint = new Paint();      clipPaint.setAntiAlias(true);      clipPaint.setStyle(Paint.Style.STROKE);      clipPaint          .setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));      canvas.drawPaint(clipPaint);      canvas.drawColor(getResources().getColor(color.transparent));      Paint paint = new Paint();      paint.setAntiAlias(true);      paint.setColor(Color.GREEN);      paint.setStyle(Style.STROKE);      paint.setStrokeWidth(5.0f);      for (int i = 0; i < numberOfFaceDetected; i++) {        Face face = faces[i];        PointF midPoint = new PointF();        // 获得两眼之间的中间点        face.getMidPoint(midPoint);        // 获得两眼之间的距离        eyesDistance = face.eyesDistance();        // 换算出预览图片和屏幕显示区域的比例参数        float scale_x = mWidth / 500;        float scale_y = mHeight / 600;        Log.e("eyesDistance=", eyesDistance + "");        Log.e("midPoint.x=", midPoint.x + "");        Log.e("midPoint.y=", midPoint.y + "");        // 因为拍摄的相片跟实际显示的图像是镜像关系，所以在图片上获取的两眼中间点跟手机上显示的是相反方向        canvas.drawRect((int) (240 - midPoint.x - eyesDistance)                * scale_x, (int) (midPoint.y * scale_y),            (int) (240 - midPoint.x + eyesDistance) * scale_x,            (int) (midPoint.y + 3 * eyesDistance) * scale_y, paint);      }      holder.unlockCanvasAndPost(canvas);    }  }}

 holder.setFormat(PixelFormat.TRANSPARENT); this.setZOrderOnTop(true);

public class FaceRecognitionDemoActivity extends Activity implements    OnClickListener {  private SurfaceView preview;  private Camera camera;  private Camera.Parameters parameters;  private int orientionOfCamera;// 前置摄像头的安装角度  private int faceNumber;// 识别的人脸数  private FaceDetector.Face[] faces;  private FindFaceView mFindFaceView;  private ImageView iv_photo;  private Button bt_camera;  TextView mTV;  /**   * Called when the activity is first created.   */  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);  }  @Override  protected void onStart() {    super.onStart();    iv_photo = (ImageView) findViewById(R.id.iv_photo);    bt_camera = (Button) findViewById(R.id.bt_camera);    mTV = (TextView) findViewById(R.id.show_count);    bt_camera.setOnClickListener(this);    mFindFaceView = (FindFaceView) findViewById(R.id.my_preview);    preview = (SurfaceView) findViewById(R.id.preview);    // 设置缓冲类型（必不可少）    preview.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);    // 设置surface的分辨率    preview.getHolder().setFixedSize(176, 144);    // 设置屏幕常亮（必不可少）    preview.getHolder().setKeepScreenOn(true);    preview.getHolder().addCallback(new SurfaceCallback());  }  private final class MyPictureCallback implements PictureCallback {    @Override    public void onPictureTaken(byte[] data, Camera camera) {      try {        Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0,            data.length);        Matrix matrix = new Matrix();        matrix.setRotate(-90);        Bitmap bmp = Bitmap.createBitmap(bitmap, 0, 0, bitmap            .getWidth(), bitmap.getHeight(), matrix, true);        bitmap.recycle();        iv_photo.setImageBitmap(bmp);        camera.startPreview();      } catch (Exception e) {        e.printStackTrace();      }    }  }  private final class SurfaceCallback implements Callback {    @Override    public void surfaceChanged(SurfaceHolder holder, int format, int width,                  int height) {      if (camera != null) {        parameters = camera.getParameters();        parameters.setPictureFormat(PixelFormat.JPEG);        // 设置预览区域的大小        parameters.setPreviewSize(width, height);        // 设置每秒钟预览帧数        parameters.setPreviewFrameRate(20);        // 设置预览图片的大小        parameters.setPictureSize(width, height);        parameters.setJpegQuality(80);      }    }    @Override    public void surfaceCreated(SurfaceHolder holder) {      int cameraCount = 0;      Camera.CameraInfo cameraInfo = new Camera.CameraInfo();      cameraCount = Camera.getNumberOfCameras();      //设置相机的参数      for (int i = 0; i < cameraCount; i++) {        Camera.getCameraInfo(i, cameraInfo);        if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {          try {            camera = Camera.open(i);            camera.setPreviewDisplay(holder);            setCameraDisplayOrientation(i, camera);            //最重要的设置 帧图的回调            camera.setPreviewCallback(new MyPreviewCallback());            camera.startPreview();          } catch (Exception e) {            e.printStackTrace();          }        }      }    }    @Override    public void surfaceDestroyed(SurfaceHolder holder) {    //记得释放，避免OOM和占用      if (camera != null) {        camera.setPreviewCallback(null);        camera.stopPreview();        camera.release();        camera = null;      }    }  }  private class MyPreviewCallback implements PreviewCallback {    @Override    public void onPreviewFrame(byte[] data, Camera camera) {    //这里需要注意，回调出来的data不是我们直接意义上的RGB图 而是YUV图，因此我们需要    //将YUV转化为bitmap再进行相应的人脸检测，同时注意必须使用RGB_565，才能进行人脸检测，其余无效      Camera.Size size = camera.getParameters().getPreviewSize();      YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21,          size.width, size.height, null);      ByteArrayOutputStream baos = new ByteArrayOutputStream();      yuvImage.compressToJpeg(new Rect(0, 0, size.width, size.height),          80, baos);      byte[] byteArray = baos.toByteArray();      detectionFaces(byteArray);    }  }  /**   * 检测人脸   *   * @param data 预览的图像数据   */  private void detectionFaces(byte[] data) {    BitmapFactory.Options options = new BitmapFactory.Options();    Bitmap bitmap1 = BitmapFactory.decodeByteArray(data, 0, data.length,        options);    int width = bitmap1.getWidth();    int height = bitmap1.getHeight();    Matrix matrix = new Matrix();    Bitmap bitmap2 = null;    FaceDetector detector = null;    //设置各个角度的相机，这样我们的检测效果才是最好    switch (orientionOfCamera) {      case 0:        //初始化人脸检测（下同）        detector = new FaceDetector(width, height, 10);        matrix.postRotate(0.0f, width / 2, height / 2);        // 以指定的宽度和高度创建一张可变的bitmap（图片格式必须是RGB_565，不然检测不到人脸）        bitmap2 = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);        break;      case 90:        detector = new FaceDetector(height, width, 1);        matrix.postRotate(-270.0f, height / 2, width / 2);        bitmap2 = Bitmap.createBitmap(height, width, Bitmap.Config.RGB_565);        break;      case 180:        detector = new FaceDetector(width, height, 1);        matrix.postRotate(-180.0f, width / 2, height / 2);        bitmap2 = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);        break;      case 270:        detector = new FaceDetector(height, width, 1);        matrix.postRotate(-90.0f, height / 2, width / 2);        bitmap2 = Bitmap.createBitmap(height, width, Bitmap.Config.RGB_565);        break;    }    //设置支持的面数（最大支持检测多少人的脸 ，可以根据需要调整，不过需要与findFaces中的参数数值相同，否则会抛出异常）    faces = new FaceDetector.Face[10];    Paint paint = new Paint();    paint.setDither(true);    Canvas canvas = new Canvas();    canvas.setBitmap(bitmap2);    canvas.setMatrix(matrix);    // 将bitmap1画到bitmap2上（这里的偏移参数根据实际情况可能要修改）    canvas.drawBitmap(bitmap1, 0, 0, paint);    //这里通过向findFaces中传递帧图转化后的bitmap和最大检测的人脸数face，返回检测后的人脸数    faceNumber = detector.findFaces(bitmap2, faces);    mTV.setText("facnumber----" + faceNumber);    mTV.setTextColor(Color.RED);    //这里就是我们的人脸识别，绘制识别后的人脸区域的类    if (faceNumber != 0) {      mFindFaceView.setVisibility(View.VISIBLE);      mFindFaceView.drawRect(faces, faceNumber);    } else {      mFindFaceView.setVisibility(View.GONE);    }    bitmap2.recycle();    bitmap1.recycle();  }  /**   * 设置相机的显示方向（这里必须这么设置，不然检测不到人脸）   *   * @param cameraId 相机ID(0是后置摄像头，1是前置摄像头）   * @param camera  相机对象   */  private void setCameraDisplayOrientation(int cameraId, Camera camera) {    Camera.CameraInfo info = new Camera.CameraInfo();    Camera.getCameraInfo(cameraId, info);    int rotation = getWindowManager().getDefaultDisplay().getRotation();    int degree = 0;    switch (rotation) {      case Surface.ROTATION_0:        degree = 0;        break;      case Surface.ROTATION_90:        degree = 90;        break;      case Surface.ROTATION_180:        degree = 180;        break;      case Surface.ROTATION_270:        degree = 270;        break;    }    orientionOfCamera = info.orientation;    int result;    if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {      result = (info.orientation + degree) % 360;      result = (360 - result) % 360;    } else {      result = (info.orientation - degree + 360) % 360;    }    camera.setDisplayOrientation(result);  }  @Override  public void onClick(View v) {    switch (v.getId()) {      case R.id.bt_camera:        if (camera != null) {          try {            camera.takePicture(null, null, new MyPictureCallback());          } catch (Exception e) {            e.printStackTrace();          }        }        break;    }  }}