时间：2019-09-03

概述：人脸识别

Android实现简单的人脸识别，人脸检测(这里用的是科大讯飞的人脸识别)，因此需要此库导入后，测试本代码：

private final static String TAG = MainActivity.class.getSimpleName();

private SurfaceView mPreviewSurface;//用于显示预览图像

private SurfaceView mFaceSurface;//用于绘制检测人脸的返回信息

private SurfaceHolder mSurfaceHolder;//纹理控制器

private ImageButton changeCamera;//切换摄像头按钮

private Camera mCamera;//摄像头对象

private int mCameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;//设置为默认开启前置摄像头

// 默认设置640*480,截至目前也只是支持640*480

private int PREVIEW_WIDTH = 640;

private int PREVIEW_HEIGHT = 480;

// 预览帧数据存储数组和缓存数组

private byte[] nv21;

private byte[] buffer;

// 缩放矩阵

private Matrix mScaleMatrix = new Matrix();

// 加速度感应器，用于获取手机的朝向

private Accelerometer accelerometer;

private FaceDetector mFaceDetector;//调用讯飞的SDK来实现人脸识别

private boolean stop;//人脸检测开关

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

SpeechUtility.createUtility(this, "appid=" + "5833f456"); //设置AppKey用于注册,AppID

initView();//初始化布局

initData();//初始化数据

requestPermission(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1000);

}

@Override

public void permissionSuccess(int requestCode) {

super.permissionSuccess(requestCode);

if (requestCode == 1000){

Toast.makeText(MainActivity.this,"获取文件写入权限成功！",Toast.LENGTH_SHORT).show();

}

if (requestCode == 2000){

openCamera();//打开摄像头

}

}

/**

* 用于显示摄像头拍摄到的图像

*/

private SurfaceHolder.Callback mPreviewCallback = new SurfaceHolder.Callback() {

@Override

public void surfaceDestroyed(SurfaceHolder holder) {

closeCamera();//关闭摄像头，并释放资源

}

@Override

public void surfaceCreated(SurfaceHolder holder) {

requestPermission(new String[]{Manifest.permission.CAMERA},2000);

}

@Override

public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

mScaleMatrix.setScale(width / (float) PREVIEW_HEIGHT,

height / (float) PREVIEW_WIDTH);//设置缩放比例

}

};

/**

* 设置纹理尺寸

*/

private void setSurfaceSize() {

DisplayMetrics metrics = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(metrics);

int width = metrics.widthPixels;

int height = (int) (width * PREVIEW_WIDTH / (float) PREVIEW_HEIGHT);

RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(width, height);

params.addRule(RelativeLayout.ALIGN_PARENT_TOP);

mPreviewSurface.setLayoutParams(params);

}

/**

* 初始化数据

*/

private void initData(){

nv21 = new byte[PREVIEW_WIDTH * PREVIEW_HEIGHT * 2];

buffer = new byte[PREVIEW_WIDTH * PREVIEW_HEIGHT * 2];

accelerometer = new Accelerometer(this);

mFaceDetector = FaceDetector.createDetector(this, null);//实例化人脸检测对象

}

/**

* 初始化控件

*/

private void initView() {

mPreviewSurface = (SurfaceView) findViewById(R.id.preview);

mFaceSurface = (SurfaceView) findViewById(R.id.face);

changeCamera = (ImageButton) findViewById(R.id.change);

mPreviewSurface.getHolder().addCallback(mPreviewCallback);

mSurfaceHolder = mFaceSurface.getHolder();

mSurfaceHolder.setFormat(PixelFormat.TRANSPARENT);

mFaceSurface.setZOrderOnTop(true);

// 点击SurfaceView，切换摄相头

changeCamera.setOnClickListener(v -> {

// 只有一个摄相头，不支持切换

if (Camera.getNumberOfCameras() == 1) {

Toast.makeText(this, "只有后置摄像头，不能切换", Toast.LENGTH_SHORT).show();

return;

}

closeCamera();

if (Camera.CameraInfo.CAMERA_FACING_FRONT == mCameraId) {

mCameraId = Camera.CameraInfo.CAMERA_FACING_BACK;

} else {

mCameraId = Camera.CameraInfo.CAMERA_FACING_FRONT;

}

openCamera();

});

setSurfaceSize();

}

/**

* 打开摄像头

*/

private void openCamera() {

if (mCamera != null) {

return;

}

try {

mCamera = Camera.open(mCameraId);

if (Camera.CameraInfo.CAMERA_FACING_FRONT == mCameraId) {

Toast.makeText(this, "前置摄像头已开启，点击可切换", Toast.LENGTH_SHORT).show();

} else {

Toast.makeText(this,"后置摄像头已开启，点击可切换",Toast.LENGTH_SHORT).show();

}

setCameraDisplayOrientation(this, mCameraId, mCamera);//设置摄像头的预览方向

} catch (Exception e) {

e.printStackTrace();

closeCamera();

return;

}

//获取摄像头参数对象

Camera.Parameters params = mCamera.getParameters();

//设置预览的格式

params.setPreviewFormat(ImageFormat.NV21);

//设置预览的分辨率，这里设置640*480，到目前为止只支持该分辨率的人脸检测

params.setPreviewSize(PREVIEW_WIDTH, PREVIEW_HEIGHT);

//给摄像头设置参数配置

mCamera.setParameters(params);

//给摄像头设置预览回到，这里使用的Lambda表达式代表的只有一个回调函数的匿名内部类

mCamera.setPreviewCallback((data, camera) -> System.arraycopy(data, 0, nv21, 0, data.length));

try {

mCamera.setPreviewDisplay(mPreviewSurface.getHolder());

mCamera.startPreview();

} catch (IOException e) {

e.printStackTrace();

}

}

/**

* 释放摄像头资源

*/

private void closeCamera() {

if (null != mCamera) {

mCamera.setPreviewCallback(null);

mCamera.stopPreview();

mCamera.release();

mCamera = null;

}

}

@Override

protected void onResume() {

super.onResume();

if (null != accelerometer) {

accelerometer.start();

}

stop = false;

new Thread(()->{

while (!stop) {

if (null == nv21) {

continue;

}

synchronized (nv21) {

System.arraycopy(nv21, 0, buffer, 0, nv21.length);

}

int direction = Accelerometer.getDirection();// 获取手机朝向

boolean frontCamera = (Camera.CameraInfo.CAMERA_FACING_FRONT == mCameraId);

if (frontCamera) {

direction = (4 - direction) % 4;// 0,1,2,3,4分别表示0,90,180,270和360度

}

String result = mFaceDetector.trackNV21(

buffer, PREVIEW_WIDTH, PREVIEW_HEIGHT, 1, direction);//获取人脸检测结果

FaceRect face = Result.result(result);//获取返回的数据

Log.e(TAG, "result:" + result);//输出检测结果,该结果为JSON数据

Canvas canvas =mSurfaceHolder.lockCanvas();//锁定画布用于绘制

if (null == canvas) {

continue;

}

canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);//清除之前的绘制图像

canvas.setMatrix(mScaleMatrix);

if (face == null) {

mSurfaceHolder.unlockCanvasAndPost(canvas);

continue;

}

if (face != null) {

face.bound = DrawFaceRect.RotateDeg90(face.bound, PREVIEW_HEIGHT);//绘制人脸的区域

if (face.point != null) {//绘制脸上关键点

for (int i = 0; i < face.point.length; i++) {

face.point[i] = DrawFaceRect.RotateDeg90(face.point[i], PREVIEW_HEIGHT);

}

//绘制人脸检测的区域

DrawFaceRect.drawFaceRect(canvas, face, PREVIEW_WIDTH, frontCamera);

}

} else {

Log.e(TAG, "没有检测出人脸");

}

mSurfaceHolder.unlockCanvasAndPost(canvas);

}

}).start();

}

解析人脸返回结果：

FaceRect rect = null;

if (TextUtils.isEmpty(json)) {

return null;

}

try {

JSONObject joResult = new JSONObject(json);

JSONArray items = joResult.getJSONArray("face");//解析face数组

JSONObject position = items.getJSONObject(0).getJSONObject("position");

//获取人脸检测框数据

rect = new FaceRect();

rect.bound.left = position.getInt("left");//左边起始位置点

rect.bound.top = position.getInt("top");//上端起始位置点

rect.bound.right = position.getInt("right");//右边结束位置点

rect.bound.bottom = position.getInt("bottom");//下端结束位置点

// 提取关键点数据

JSONObject landmark = items.getJSONObject(0).getJSONObject("landmark");

int keyPoint = landmark.length();//人脸检测点数据

rect.point = new Point[keyPoint];//人脸检测点数组

Iterator it = landmark.keys();//使用迭代器解析人脸监测点数据

int point = 0;

while (it.hasNext()) {//检测点，的坐标

String key = (String) it.next();

JSONObject object = landmark.getJSONObject(key);

rect.point[point] = new Point(object.getInt("x"), object.getInt("y"));

point++;

}

} catch (JSONException e) {

e.printStackTrace();

}

return rect;